WIP Eta Carinae and the Carina Nebula images

 The following image is a work in progress set of narrowband images of the Carina Nebula (NGC 3372) taken with iTelescope T33 over three 30-minute sessions on 4/2/25, 4/425 and 4/5/25.

A standard Hubble SHO palette is used, so SII emission is red, H-alpha is green, and OIII emission is blue. No noise reduction other than the improved signal-to-noise afforded by image stacking (7x 3-minute H-alpha images, 6x 3-minute OIII images, and 9x 3-minute SII images).

 

Interesting Astrophysics: Apr 05 to Apr 16

The last two weeks have produced quite a number of interesting papers and preprints. Given the diversity I'll let them speak for themselves. Note to self: two papers on cloud statistics.

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Galaxies and Starbursts

An Empirical Characterization of Extended Cool Gas Around Galaxies Using MgII Absorption Features
Hsiao-Wen Chen, Jennifer E. Helsby, Jean-Rene Gauthier, Stephen A. Shectman, Ian B. Thompson, Jeremy L. Tinker, arXiv:1004.0705 [pdf, ps, other]

Comments: 20 pages, 13 figures; to appear in the Astrophysical Journal 2010 May 10 issue; a version with higher resolution figures can be found at this http URL

From their abstract: "... The lack of correlation between Wr(2796) and galaxy colors suggests a lack of physical connection between the origin of extended MgII halos and recent star formation history of the galaxies ..."

Seeing Through the Trough: Outflows and the Detectability of Lyman Alpha Emission from the First Galaxies
Mark Dijkstra, Stuart Wyithe, arXiv:1004.2490 [pdf, ps, other]
Comments: 11 pages, 7 figures, submitted to MNRAS

From their abstract: "In this paper we demonstrate that the radiative transfer effects in the interstellar medium (ISM), which cause Lya flux to emerge from galaxies at frequencies where the Gunn-Peterson optical depth is reduced, can substantially enhance the prospects for detection of the Lya line at high redshift. In particular, scattering off outflows of interstellar HI gas can modify the Lya spectral line shape such that >5% of the emitted Lya radiation is transmitted directly to the observer, even through a fully neutral IGM. It may therefore be possible to directly observe `strong' Lya emission lines (EW > 50 Angstrom rest frame) from the highest redshift galaxies that reside in the smallest HII `bubbles' early in the reionization era with JWST. In addition, we show that outflows can boost the fraction of Lya radiation that is transmitted through the IGM during the latter stages of reionization, and even post-reionization."

The Great Observatories All-Sky LIRG Survey: Comparison of Ultraviolet and Far-Infrared Properties
Justin H. Howell, et al, arXiv:1004.0985 [pdf, ps, other]
Comments: 37 pages, 10 figures, accepted for publication in ApJ

From their abstract: "The Great Observatories All-sky LIRG Survey (GOALS) consists of a complete sample of 202 Luminous Infrared Galaxies (LIRGs) selected from the IRAS Revised Bright Galaxy Sample (RBGS). The galaxies span the full range of interaction stages, from isolated galaxies to interacting pairs to late stage mergers. We present a comparison of the UV and infrared properties of 135 galaxies in GOALS observed by GALEX and Spitzer. For interacting galaxies with separations greater than the resolution of GALEX and Spitzer (2-6"), we assess the UV and IR properties of each galaxy individually. The contribution of the FUV to the measured SFR ranges from 0.2% to 17.9%, with a median of 2.8% and a mean of 4.0 +/- 0.4%. The specific star formation rate of the GOALS sample is extremely high, with a median value (3.9*10^{-10} yr^{-1}) that is comparable to the highest specific star formation rates seen in the Spitzer Infrared Nearby Galaxies Survey sample."

Dwarf-Galaxy Cosmology
Regina Schulte-Ladbeck, Ulrich Hopp, Elias Brinks, Andrey Kravtsov, arXiv:1004.1139 [pdf, other]
Comments: This is the editorial paper which introduces the Special Issue on Dwarf-Galaxy Cosmology published in Advances in Astronomy. The issue contains fourteen review papers, and one original research article. All papers were peer-reviewed by a minimum of two referees. To read the Special Issue, please follow this link: this http URL .

Their abstract: "Dwarf galaxies provide opportunities for drawing inferences about the processes in the early universe by observing our "cosmological backyard"-the Local Group and its vicinity. This special issue of the open-access journal Advances in Astronomy is a snapshot of the current state of the art of dwarf-galaxy cosmology."

Sadly no articles focussing on outflows or supernova feedback.

Comparing Ultraviolet and Infrared-Selected Starburst Galaxies in Dust Obscuration and Luminosity
Lusine A. Sargsyan, Daniel W. Weedman, James R. Houck, arXiv:1004.1551 [pdf, ps, other]
Comments: accepted for publication in The Astrophysical Journal

Concludes that the "obscuration corrections by factors of two to three determined from reddening of the ultraviolet continuum for Lyman Break Galaxies with z > 2 are insufficient, and should be at least a factor of 10 for M(UV) about -17, with decreasing correction for more luminous sources."

A Multi-wavelength analysis of M81: insight on the nature of Arp's loop
A. Sollima, A. Gil de Paz, D. Martinez-Delgado, R.J. Gabany, J. Gallego, T. Hallas, arXiv:1004.1610 [pdf, ps, other]
Comments: 7 pages, 7 figures, accepted for publication by A&A

Their abstract: "The optical ring like structure detected by Arp (1965) around M81 (commonly referenced as "Arp's loop") represents one of the most spectacular feature observed in nearby galaxies. Arp's loop is commonly interpreted as a tail resulting from the tidal interaction between M81 and M82. However, since its discovery the nature of this feature has remained controversial. Aims: Our primary purpose was to identify the sources of optical and infrared emission observed in Arp's loop. Methods: The morphology of the Arp's loop has been investigated with deep wide-field optical images. We also measured its colors using IRAS and Spitzer-MIPS infrared images and compared them with those of the disk of M81 and Galactic dust cirrus that fills the area where M81 is located. Results: Optical images reveal that this peculiar object has a filamentary structure characterized by many dust features overlapping M81's field. The ratios of far-infrared fluxes and the estimated dust-to-gas ratios indicate the infrared emission of Arp's loop is dominated by the contribution of cold dust that is most likely from Galactic cirrus. Conclusions: The above results suggest that the light observed at optical wavelengths is a combination of emission from i) a few recent star forming regions located close to M81, where both bright UV complexes and peaks in the HI distribution are found, ii) the extended disk of M81 and iii) scattered light from the same Galactic cirrus that is responsible for the bulk of the far infrared emission."

I've mentioned the Galactic cirrus emission along the line of sight to the M81/M82 group previously in this blog, as the cirrus is visible even in scattered optical/UV light. Amateur astronomers have termed this cirrus-associated nebulosity Integrated Flux Nebulae.

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Black Holes and AGN

Momentum-driven winds and positive AGN feedback
Joe Silk, Adi Nusser, arXiv:1004.0857 [pdf, ps, other]
Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO)

Their abstract: "Force balance considerations put a limit on the rate of AGN radiation momentum output, $L/c$, capable of driving galactic superwinds. We show that this condition is insufficient: black holes obeying the observed $\mbh -\sigma $ relation cannot supply enough energy in radiation which can drive the gas out by pressure alone. The shortfall is by up to an order of magnitude in most, but not all, cases. We propose that outflow-triggering of star formation by enhancing the intercloud medium turbulent pressure and squeezing clouds can supply the necessary boost, and suggest possible tests of this hypothesis. We further point out that the time-scales for Bondi accretion and for orbital decay of merging clumps by dynamical friction in the nuclear disk around a central black hole both follow a similar scaling with mass, favoring the most massive black holes, but the latter process is up to two orders of magnitude more rapid at $z\gtsim 10.$ The combination of accretion and coalescence results in earlier formation of more massive black holes, and, in particular, can account for the masses of the black holes inferred to power AGN at $z\sim 6.$"

Molecular clouds: X-ray mirrors of the Galactic nuclear activity
Gabriele Ponti, Regis Terrier, Andrea Goldwurm, Guillaume Belanger, Guillaume Trap, arXiv:1004.1412 [pdf, ps, other]
Comments: 4 pages, "The Galactic Center: A Window on the Nuclear Environment of Disk Galaxies" ASP Conference Series, 2010 eds: M. Morris, D. Q. Wang and F. Yuan

Did the supermassive black hole that currently lurks quietly at the center of our Galaxy flare up about 100 years ago?

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Interstellar Medium

The Mass-Size Relation from Clouds to Cores. II. Solar Neighborhood Clouds
Jens Kauffmann, Thushara Pillai, Rahul Shetty, Philip C. Myers, Alyssa A. Goodman, arXiv:1004.1170 [pdf, ps, other]
Comments: accepted to the Astrophysical Journal

I must read this more carefully.

Abstract in full: "We measure the mass and size of cloud fragments in several molecular clouds continuously over a wide range of spatial scales (0.05 < r / pc < 3). Based on the recently developed "dendrogram-technique", this characterizes dense cores as well as the enveloping clouds. "Larson's 3rd Law" of constant column density, m(r) = C*r^2, is not well suited to describe the derived mass-size data. Solar neighborhood clouds not forming massive stars (< 10 M_sun; Pipe Nebula, Taurus, Perseus, and Ophiuchus) obey m(r) < 870 M_sun (r / pc)^1.33 . In contrast to this, clouds forming massive stars (Orion A, G10.15$-$0.34, G11.11$-$0.12) do exceed the aforementioned relation. Thus, this limiting mass-size relation may approximate a threshold for the formation of massive stars. Across all clouds, cluster-forming cloud fragments are found to be---at given radius---more massive than fragments devoid of clusters. The cluster-bearing fragments are found to roughly obey a mass-size law m = C*r^1.27 (where the exponent is highly uncertain in any given cloud, but is certainly smaller than 1.5).

Physical Properties of Giant Molecular Clouds in the Large Magellanic Cloud
A. Hughes, et al, arXiv:1004.2094 [pdf, ps, other]
Comments: 28 pages, 10 figures, accepted by MNRAS

Searching for Diffuse Nonthermal X-Rays from the Superbubbles N11 and N51D in the Large Magellanic Cloud
H. Yamaguchi, M. Sawada, A. Bamba, arXiv:1004.0753 [pdf, ps, other]
Comments: 9 pages, accepted for publication in ApJ.

Their abstract (emphasis mine): "We report on observations of the superbubbles (SBs) N11 and N51D in the Large Magellanic Cloud (LMC) with Suzaku and XMM-Newton. The interior of both SBs exhibits diffuse X-ray emission, which is well represented by thin thermal plasma models with a temperature of 0.2-0.3keV. The presence of nonthermal emission, claimed in previous works, is much less evident in our careful investigation. The 3-sigma upper limits of 2-10keV flux are 3.6*10^{-14}ergs/cm^2/s and 4.7*10^{-14}ergs/cm^2/s for N11 and N51D, respectively. The previous claims of the detection of nonthermal emission are probably due to the inaccurate estimation of the non X-ray background. We conclude that no credible nonthermal emission has been detected from the SBs in the LMC, with the exception of 30 Dor C. "

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Hydrodynamics and Numerical Astrophysics

A comparison between grid and particle methods on the statistics of driven, supersonic, isothermal turbulence
Daniel J. Price, Christoph Federrath, arXiv:1004.1446 [pdf, ps, other]

Comments: 16 pages, 15 figures, accepted to MNRAS. Associated movies, images and full res version at: this http URL

The Athena Astrophysical MHD Code in Cylindrical Geometry
Aaron Skinner, Eve Ostriker, arXiv:1004.2487 [pdf, ps, other]

Their abstract: "A method for implementing cylindrical coordinates in the Athena magnetohydrodynamics (MHD) code is described. The extension follows the approach of Athena's original developers and has been designed to alter the existing Cartesian-coordinates code as minimally and transparently as possible. The numerical equations in cylindrical coordinates are formulated to maintain consistency with constrained transport, a central feature of the Athena algorithm, while making use of previously implemented code modules such as the Riemann solvers. Angular-momentum transport, which is critical in astrophysical disk systems dominated by rotation, is treated carefully. We describe modifications for cylindrical coordinates of the higher-order spatial reconstruction and characteristic evolution steps as well as the finite-volume and constrained transport updates. Finally, we present a test suite of standard and novel problems in one-, two-, and three-dimensions designed to validate our algorithms and implementation and to be of use to other code developers. The code is suitable for use in a wide variety of astrophysical applications and is freely available for download on the web."

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Instrumentation

The New Hard X-ray Mission
G. Tagliaferri, et al, arXiv:1004.2691 [pdf]
Comments: 9 pages, 5 figures. Accepted for publication on PoS, proceedings of "The Extreme sky: Sampling the Universe above 10 keV", held in Otranto (Italy), 13-17 October 2009

Their abstract: "The Italian New Hard X-ray Mission (NHXM) has been designed to provide a real breakthrough on a number of hot astrophysical issues that includes: black holes census, the physics of accretion, the particle acceleration mechanisms, the effects of radiative transfer in highly magnetized plasmas and strong gravitational fields. NHXM is an evolution of the HEXIT-Sat concept and it combines fine imaging capability up to 80 keV, today available only at E<10 keV, with sensitive photoelectric imaging polarimetry. It consists of four identical mirrors, with a 10 m focal length, achieved after launch by means of a deployable structure. Three of the four telescopes will have at their focus identical spectral-imaging cameras, while X-ray imaging polarimetric cameras will be placed at the focus of the fourth. In order to ensure a low and stable background, NHXM will be placed in a low Earth equatorial orbit. In this paper we provide an overall description of this mission that is currently in phase B."

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Stars, Supernovae and Planets

One-sided Outflows/Jets from Rotating Stars with Complex Magnetic Fields
R.V.E. Lovelace, M.M. Romanova, G.V. Ustyugova, A.V. Koldoba, arXiv:1004.0385 [pdf, other]
Comments: 10 pages, 11 figures

Dusty Disks around White Dwarfs I: Origin of Debris Disks
Ruobing Dong, Yan Wang, D. N.C. Lin, X.-W. Liu, arXiv:1004.0696 [pdf, ps, other]
Comments: 38 pages, 7 figures, single column, accepted by ApJ

Interesting Astrophysics: 22 Feb to 05 Mar, 2010

Of particular interest (to me at least) are a variety of papers related to galactic winds. The AKARI observations of Kaneda et al probe dust in M82's wind; Steidel et al use absorption lines probe the distribution and kinematics gas around redshift z~2-3 LBGs at impact parameters of - to ~100 kpc; Nestor et al propose to understand ultra-strong Mg II absorbers in the context of galactic winds; Alexander et al present evidence for a galactic wind in z~2 ULIRG; Sumui et al present a theoretical mixed Cosmic-ray/thermal wind model; and Pinsonneault et al consider the effects of galactic winds anisotropy in cosmological simulations.

In a similar vein, albeit not quite galactic winds, there is a conference proceedings by Proga et al on large scale outflows from AGN, and papers on dust in HII regions (Draine) and in wind-blown bubbles (Everett & Churchwell).

Quite of a few of these papers were noted in previous editions of "Interesting Astrophysics" when they appeared as preprints on arXiv.org, but its worth noting them again with their full journal reference information.

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Galaxies and Starbursts

Large-scale distributions of mid- and far-infrared emission from the center to the halo of M82 revealed with AKARI
H. Kaneda, D. Ishihara, T.Suzuki, N. Ikeda, T. Onaka, M. Yamagishi, Y. Ohyama, T. Wada, A. Yasuda, arXiv:1002.4521 [pdf, ps, other]
Comments: 12 pages, 8 figures, accepted for publication in A&A

Full abstract: "The edge-on starburst galaxy M82 exhibits complicated distributions of gaseous materials in its halo, which include ionized superwinds driven by nuclear starbursts, neutral materials entrained by the superwinds, and large-scale neutral streamers probably caused by a past tidal interaction with M81. We investigate detailed distributions of dust grains and polycyclic aromatic hydrocarbons (PAHs) around M82 to understand their interplay with the gaseous components. We performed mid- (MIR) and far-infrared (FIR) observations of M82 with the Infrared Camera and Far-Infrared Surveyor on board AKARI. We obtain new MIR and FIR images of M82, which reveal both faint extended emission in the halo and very bright emission in the center with signal dynamic ranges as large as five and three orders of magnitude for the MIR and FIR, respectively. We detect MIR and FIR emission in the regions far away from the disk of the galaxy, reflecting the presence of dust and PAHs in the halo of M82. We find that the dust and PAHs are contained in both ionized and neutral gas components, implying that they have been expelled into the halo of M82 by both starbursts and galaxy interaction. In particular, we obtain a tight correlation between the PAH and H$\alpha$ emission, which provides evidence that the PAHs are well mixed in the ionized superwind gas and outflowing from the disk."

Discovery of an unusual new radio source in the star-forming galaxy M82: Faint supernova, supermassive blackhole, or an extra-galactic microquasar?
T. W. B. Muxlow, R. J. Beswick, S. T. Garrington, A. Pedlar, D. M. Fenech, M. K. Argo, J. van Eymeren, M. Ward, A. Zezas, A. Brunthaler, arXiv:1003.0994 [pdf, ps, other]
Comments: 6 pages, 3 figures (2 colour), MNRAS letters accepted

The Structure and Kinematics of the Circum-Galactic Medium from Far-UV Spectra of z~2-3 Galaxies
C. C. Steidel, D. K. Erb, A. E. Shapley, M. Pettini, N. A. Reddy, M. Bogosavljević, G. C. Rudie, O. Rakic, arXiv:1003.0679 [pdf, ps, other]
Comments: Submitted to ApJ, 22 February 2010. 32 pages, 24 figures

Full abstract: "We present new results on the kinematics and spatial distribution of metal-enriched gas within 125 kpc (physical) of Lyman Break galaxies at redshifts z~2-3. In particular, we demonstrate how rest-UV galaxy spectra can be used to obtain key spatial and spectral information more efficiently than possible with QSO sightlines. After recalibrating the measurement of galaxy systemic redshifts from their UV spectra, we investigate the kinematics of galaxy-scale outflows via the strong interstellar (IS) absorption and Lya emission lines (when present), as well as their dependence on other physical properties of the galaxies. We construct a sample of 512 close (1-15 arcsec) angular pairs of z~2-3 LBGs in which the spectra background galaxies probe the circumgalactic gas surrrounding those in the foreground. The close pairs, together with spectra of the foreground galaxies themselves, sample galactocentric impact parameters b=0-125 kpc (physical) at <z>=2.2. The ensemble provides a spatial map of cool gas as a function of galactocentric distance for a well-characterized population of galaxies. We propose a simple model that simultaneously matches the kinematics, depth, and profile shape of IS absorption and Lya emission lines, as well as the observed variation of absorption line strength (of HI, CII, CIV, SiII, SiIV) versus galactocentric impact parameter. We discuss the results of the observations in the context of "cold accretion", in which cool gas accretes via filamentary streams directly onto the central regions of galaxies. At present, we find little observational support for cool infalling material, whereas evidence supporting the large-scale effects of outflows is strong. Reconciling theory and observation on the subject of gas flows into and out of forming galaxies seems necessary."

The SAURON project – XVI. On the sources of ionization for the gas in elliptical and lenticular galaxies
Marc Sarzi, et al, 2010, MNRAS, 402, 2187
Full Text: HTML, PDF (Size: 15234K)

From their abstract: "Finally, in the most massive and slowly or non-rotating galaxies in our sample, which can retain a massive X-ray halo, the finding of a spatial correlation between the hot and warm phases of the interstellar medium (ISM) suggests that the interaction with the hot ISM provides an additional source of ionization besides old ultraviolet-bright stars."

Note that they consider the X-ray gas static, as opposed to the SN Ia-driven wind scenario favored by Wang. Of course the kinematics of the WIM should provide insight into whether there is a bulk flow or not...

AINUR: Atlas of Images of NUclear Rings
S. Comerón, J. H. Knapen, J. E. Beckman, E. Laurikainen, H. Salo, I. Martínez-Valpuesta and R. J. Buta, 2010, MNRAS, 402, 2462
Full Text: HTML, PDF (Size: 10365K)

Cosmic ray driven outflows from high-redshift galaxies
Saumyadip Samui, Kandaswamy Subramanian and Raghunathan Srianand, 2010, MNRAS, 402, 2778
Full Text: HTML, PDF (Size: 1035K)

Searching for evidence of energetic feedback in distant galaxies: a galaxy wide outflow in a z ≈ 2 ultraluminous infrared galaxy
D. M. Alexander, A. M. Swinbank, Ian Smail, R. McDermid and N. P. H. Nesvadba, MNRAS, 402, 2211
Full Text: HTML, PDF (Size: 1066K)

Anisotropic Galactic Outflows and Enrichment of the Intergalactic Medium. II. Numerical Simulations

Steeve Pinsonneault, Hugo Martel, Matthew M. Pieri, arXiv:1002.4881 [pdf, ps, other]

Comments: Submitted to ApJ. Figures 4, 5 and 6 are not included because of their large sizes. They can be downloaded from: this http URL

Large scale outflows from z ~ 0.7 starburst galaxies identified via ultra-strong MgII quasar absorption lines
Daniel B. Nestor, Benjamin D. Johnson, Vivienne Wild, Brice Ménard, David A. Turnshek, Sandhya Rao, Max Pettini, arXiv:1003.0693 [pdf, ps, other]
Comments: 14 pages, 6 figure, to be submitted to MNRAS

Their abstract: "(Abridged) Star formation-driven outflows are a critically important phenomenon in theoretical treatments of galaxy evolution, despite our limited ability to trace them across cosmological timescales. It has been suggested that the strongest QAL systems might arise in such outflows. If confirmed, "Ultra-strong" MgII (USMgII) absorbers may identify galactic winds over a huge baseline in cosmic time, independently of the luminous properties of the galaxy. To this end, we present the first detailed imaging/spectroscopic study of the fields of two USMgII absorber systems culled from a statistical absorber catalog, to investigate the physical processes leading to the large velocity spreads that define such systems. Each field contains two bright emission-line galaxies at similar redshift to that of the absorption. Their specific SFRs are among the highest for their masses at these redshifts, and their 4000A break and Balmer absorption strengths imply they have undergone recent (~ 0.01-1 Gyr) starbursts. The concomitant presence of two rare phenomena - starbursts and USMgII absorbers - strongly implies a causal connection. We consider these data and USMgII absorbers in general in the context of various models, and conclude that galactic outflows are generally necessary to account for the velocity-extent of the absorption, favouring starburst driven outflows over tidally-stripped gas from a major interaction which triggered the starburst. Unlike past discoveries of blueshifted gas in the spectra of galaxies at cosmological distances, identifying outflows in this manner unambiguously demonstrates that the material reaches the IGM. Finally, we discuss the implications of these results and speculate on the overall contribution of such systems to the global SFR density at z ~ 0.7."

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Black Holes and AGN

Large-Scale Outflows from AGN: a link between central black holes and galaxies
Daniel Proga, Ryuichi Kurosawa, Kentaro Nagamine, arXiv:1002.4896 [pdf, ps, other]
Comments: 8 pages, 2 figures. To be published in the Proceedings of IAU Symposium 267 "Co-Evolution of Central Black Holes and Galaxies"

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Cosmology

A sub-resolution multiphase interstellar medium model of star formation and SNe energy feedback
Giuseppe Murante, Pierluigi Monaco, Martina Giovalli, Stefano Borgani, Antonaldo Diaferio, arXiv:1002.4122 [pdf, ps, other]
Comments: 23 pages, 26 figures, MNRAS accepted

Note to self: I need to have a careful look at what they assume about the energy efficiency of SN feedback.

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Interstellar Medium and Hydrodynamics

On Radiation Pressure in Static, Dusty HII Regions

B. T. Draine, arXiv:1003.0474 [pdf, ps, other]

Comments: submitted to ApJ

Dusty Wind-Blown Bubbles
John E. Everett, Ed Churchwell, arXiv:1003.0838 [pdf, ps, other]
Comments: 13 pages, 14 figures, Accepted to ApJ

rpSPH: a much improved Smoothed Particle Hydrodynamics Algorithm
Tom Abel, arXiv:1003.0937 [pdf, other]
Comments: 14 pages, 11 figures, submitted to MNRAS. Comments welcome

Let the flame wars among the SPH community commence!

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Stars, Supernovae and Planets

Bacterial survival in Martian conditions
Giuseppe Galletta; Giulio Bertoloni; Maurizio D'Alessandro, arXiv:1002.4077 [pdf, ps, other]
Comments: 5 pages, 3 figures, special issue of Planetary and Space science on Methane on Mars discovery. Topics: Astrobiology - Methods: laboratory - Mars - Panspermia

Full abstract: "We shortly discuss the observable consequences of the two hypotheses about the origin of life on Earth and Mars: the Lithopanspermia (Mars to Earth or viceversa) and the origin from a unique progenitor, that for Earth is called LUCA (the LUCA hypothesis). To test the possibility that some lifeforms similar to the terrestrial ones may survive on Mars, we designed and built two simulators of Martian environments where to perform experiments with different bacterial strains: LISA and mini-LISA. Our LISA environmental chambers can reproduce the conditions of many Martian locations near the surface trough changes of temperature, pressure, UV fluence and atmospheric composition. Both simulators are open to collaboration with other laboratories interested in performing experiments on many kind of samples (biological, minerals, electronic) in situations similar to that of the red planet. Inside LISA we have studied the survival of several bacterial strains and endospores. We verified that the UV light is the major responsible of cell death. Neither the low temperature, nor the pressure, nor the desiccation or the atmospheric changes were effective in this sense. We found that some Bacillus strains have a particular capability to survive for some hours in Martian conditions without being screened by dust or other shields. We also simulated the coverage happening on a planet by dust transported by the winds, blowing on the samples a very small quantity of volcanic ash grains or red iron oxide particles. Samples covered by these dust grains have shown a high percentage of survival, indicating that under the surface dust, if life were to be present on Mars in the past, some bacteria colonies or cells could still be present."

Interesting Astrophysics: Feb 01 to Feb 19, 2010

I have no time to provide commentary, so without further interruption here are the papers and preprints that I consider interesting that have appeared over the period Feb 01-19, 2010.

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Galaxies and Starbursts

The AGN properties of the starburst galaxy NGC 7582
T.V. Ricci, J.E. Steiner, R.B. Menezes, A. Garcia-Rissmann, R. Cid Fernandes, arXiv:1001.5269 [ps, pdf, other]
Comments: 1 page, 2 figures, to be published in the Proceedings of the IAU Symposium no. 267

The stellar populations of the AGN/Starburst galaxy NGC7582
T.V. Ricci, J.E. Steiner, R.B. Menezes, A. Garcia-Rissmann, R. Cid Fernandes, arXiv:1001.5271 [ps, pdf, other]
Comments: 2 pages, 2 figures, to be published in the Proceedings of the IAU Symposium no. 262

Their abstract: "NGC 7582 is defined as a Starburst/AGN galaxy, since its optical and X-Ray spectra reveal both characteristics. In this work, we show the results of a stellar population modeling in a datacube taken with the Gemini South telescope. We found that $\sim$ 90% of the light in the field of view is emitted by stars that are less than 1 billion years old. A strong burst occurred about $\sim$ 6 million years ago and has nearly solar metallicity. We also found a Wolf-Rayet cluster."

Star Formation in the Outer Filaments of NGC 1275
R.E.A. Canning, A.C. Fabian, R.M. Johnstone, J.S. Sanders, C.J. Conselice, C.S. Crawford, J.S. Gallagher III, E. Zweibel, arXiv:1002.1056 [pdf, ps, other]
Comments: Accepted for publication in MNRAS, 14 pages, 14 figures, 3 tables

A panoramic view of the Milky Way analogue NGC 891
M. Mouhcine, R. Ibata, M. Rejkuba, arXiv:1002.0461 [pdf, ps, other]
Comments: 2 figures, Apj Letter, in press

A panoramic view of M81: New stellar systems in the debris field
M. Mouhcine, R. Ibata, arXiv:1002.0456 [pdf, ps, other]
Comments: 8 pages, MNRAS

Evidence of Early Enrichment of the Galactic Disk by Large-Scale Winds
T. Tsujimoto, J. Bland-Hawthorn, K.C. Freeman, arXiv:1002.3181 [pdf, ps, other]
Comments: 9 pages including 5 figures, accepted for publication in PASJ

Starburst evolution: free-free absorption in the radio spectra of luminous IRAS galaxies
M. S. Clemens, A. Scaife, O. Vega, A. Bressan, arXiv:1002.3334 [pdf, ps, other]
Comments: 13 pages, 5 figures, accepted by MNRAS

Metal-line emission from the warm-hot intergalactic medium: II. Ultraviolet
Serena Bertone, Joop Schaye, C.M. Booth, Claudio Dalla Vecchia, Tom Theuns, Robert P.C. Wiersma, arXiv:1002.3393 [pdf, ps, other]
Comments: 21 pages, 22 figures. Submitted to MNRAS

Their abstract: "Approximately half the baryons in the local Universe are thought to reside in the warm-hot intergalactic medium (WHIM). Emission lines from metals in the UV band are excellent tracers of the cooler fraction of this gas. We present predictions for the surface brightness of a sample of UV lines that could potentially be observed by the next generation of UV telescopes at z<1. We use a subset of simulations from the OWLS project to create emission maps and to investigate the effect of varying the physical prescriptions for star formation, supernova and AGN feedback, chemodynamics and radiative cooling. Most models produce results in agreement within a factor of a few, indicating that the predictions are robust. Of the lines we consider, C III is the strongest line, but it typically traces gas colder than 10^5 K. The same is true for Si IV. The second strongest line, C IV, traces circum-galactic gas with T~10^5 K. O VI and Ne VIII probe the warmer (T~10^5.5 K and T~10^6 K, respectively) and more diffuse gas that may be a better tracer of the large scale structure. N V emission is intermediate between C IV and O VI. The intensity of all emission lines increases strongly with gas density and metallicity, and for the bright emission it is tightly correlated with the temperature for which the line emissivity is highest. In particular, the C III, C IV, Si IV and O VI emission that is sufficiently bright to be potentially detectable in the near future (>10^3 photon/s/cm^2/sr), comes from relatively dense (rho>10^2 rho_mean) and metal rich (Z>0.1 Z_sun) gas. As such, emission lines are highly biased tracers of the missing baryons and are not an optimal tool to close the baryon budget. However, they do provide a powerful means to detect the gas cooling onto or flowing out of galaxies and groups. (Abridged)"

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Black Holes and AGN

Timing the starburst-AGN connection
Vivienne Wild, Timothy Heckman, Stephane Charlot, arXiv:1002.3156 [pdf, ps, other]
Comments: 16 pages, 12 figures, accepted for publication in MNRAS

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Interstellar Medium

Metal-Ion Absorption in Conductively Evaporating Clouds
Orly Gnat, Amiel Sternberg, Christopher F. McKee, arXiv:1002.1309 [pdf, ps, other]
Comments: Submitted to ApJ

ITERA: IDL Tool for Emission-line Ratio Analysis
Brent Groves, Mark Allen, arXiv:1002.3372 [pdf, ps, other]

Comments: Accepted for New Astronomy, 3 figures. ITERA tool available to download from this http URL

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Stars, Supernove and Planets

The Birth Environment of the Solar System
Fred C. Adams, arXiv:1001.5444 [ps, pdf, other]
Comments: 58 pages including 7 figures, to appear in Annual Reviews of Astronomy and Astrophysics (2010, Vol. 48)

Absract in full: "This paper reviews our current understanding of the possible birth environments of our Solar System. Since most stars form within groups and clusters, the question becomes one of determining the nature of the birth aggregate of the Sun. This discussion starts by reviewing Solar System properties that provide constraints on our environmental history. We then outline the range of star-forming environments that are available in the Galaxy, and discuss how they affect star and planet formation. The nature of the solar birth cluster is constrained by many physical considerations, including radiation fields provided by the background environment, dynamical scattering interactions, and by the necessity of producing the short-lived radioactive nuclear species inferred from meteoritic measurements. Working scenarios for the solar birth aggregate can be constructed, as discussed herein, although significant uncertainties remain."

A scenario of planet erosion by coronal radiation
J. Sanz-Forcada, I. Ribas, G. Micela, A. M. T. Pollock, D. Garcia-Alvarez, E. Solano, C. Eiroa, arXiv:1002.1875 [pdf, ps, other]
Comments: Accepted by A&A Letters (8 Feb. 2010). 4 pages, 3 figures, 1 online table (included)

On the Disruption of Star Clusters in a Hierarchical Interstellar Medium
Bruce G. Elmegreen, Deidre A. Hunter, arXiv:1002.2823 [pdf, ps, other]
Comments: ApJ vol. 712, March 20, 2010, 33 pages 15 figures

Do Wolf-Rayet stars have similar locations in hosts as type Ib/c supernovae and long gamma-ray bursts?
G. Leloudas, J. Sollerman, A. J. Levan, J. P. U. Fynbo, D. Malesani, J. R. Maund, arXiv:1002.3164 [pdf, ps, other]
Comments: Under review in A&amp;A. The present version includes suggestions from the referee

Interesting Astrophysics: Dec 07 to 18

Not a white christmas but a windy one: Razoumov, Westmoquette et al, Rubin et al, Vanzella et al, Crenshaw et al, and Kobulnicky et al are all wind-related papers or preprints (and mainly on galactic winds). Another paper of particular note is Welsh et al's amazing 3-D mapping of the local neutral ISM (within 300 pc) using NaI and CaII absorption line spectroscopy toward 1857 nearby early-type stars.

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Galaxies and Starbursts

Damped Lyα Absorber Kinematics and Outflows from Starburst Galaxies
Razoumov, Alexei O., 2009, The Astrophysical Journal, Volume 707, Issue 1, pp. 738-749.
PDF (1.84 MB) | HTML

VLT/FLAMES-ARGUS observations of stellar wind-ISM cloud interactions in NGC 6357
Westmoquette, M. S.; Slavin, J. D.; Smith, L. J.; Gallagher, J. S., III, 2009, MNRAS, in press
Full Text: HTML, PDF (Size: 2563K)

PAH processing in a hot gas
E. R. Micelotta, A. P. Jones, A. G. G. M. Tielens, arXiv:0912.1595 [ps, pdf, other]
Comments: 16 pages, 11 figures, accepted for publication in Astronomy and Astrophysics

From their abstract: "The PAH lifetime in a tenuous hot gas (n_H ~ 0.01 cm^-3, T ~ 10^7 K), typical of the coronal gas in galactic outflows, is found to be about thousand years, orders of magnitude shorter than the typical lifetime of such objects. Conclusions: In a hot gas, PAHs are principally destroyed by electron collisions and not by the absorption of X-ray photons from the hot gas. The resulting erosion of PAHs occurs via C_2 loss from the periphery of the molecule, thus preserving the aromatic structure. The observation of PAH emission from a million degree, or more, gas is only possible if the emitting PAHs are ablated from dense, entrained clumps that have not yet been exposed to the full effect of the hot gas."

The Persistence of Cool Galactic Winds in High Stellar Mass Galaxies Between z~1.4 and ~1
Kate H. R. Rubin, Benjamin J. Weiner, David C. Koo, Crystal L. Martin, J. Xavier Prochaska, Alison L. Coil, Jeffrey A. Newman, arXiv:0912.2343 [ps, pdf, other]
Comments: Submitted to ApJ. 25 pages, 19 figures, Figure 2 reduced in resolution. Uses emulateapj format

From their abstract: "We present an analysis of the MgII 2796, 2803 and FeII 2586, 2600 absorption line profiles in coadded spectra of 468 galaxies at 0.7 < z < 1.5. ... The outflows
have hydrogen column densities N(H) > 10^19.3 cm^-2, and extend to velocities
of ~500 km/s. While galaxies with SFR > 10 Msun/yr host strong outflows in both
this and the W09 sample, we do not detect outflows in lower-SFR (i.e., log
M_*/Msun < 10.5) galaxies at lower redshifts. Using a simple galaxy evolution
model which assumes exponentially declining SFRs, we infer that strong outflows
persist in galaxies with log M_*/Msun > 10.5 as they age between z=1.4 and z~1,
presumably because of their high absolute SFRs. Finally, using high resolution
HST/ACS imaging in tandem with our spectral analysis, we find evidence for a
weak trend (at 1 sigma significance) of increasing outflow absorption strength
with increasing galaxy SFR surface density."

The unusual NIV]-emitter galaxy GDS J033218.92-275302.7: star formation or AGN-driven winds from a massive galaxy at z=5.56
E. Vanzella, A. Grazian, M. Hayes, L. Pentericci, D. Schaerer, M. Dickinson, S. Cristiani, M. Giavalisco, A. Verhamme, M. Nonino, P. Rosati, arXiv:0912.3007 [ps, pdf, other]
Comments: 13 pages, 9 figures. Accepted for publication in Astronomy and Astrophysics

The central energy source of 70micron-selected galaxies: Starburst or AGN?
M. Symeonidis, D. Rosario, A. Georgakakis, J. Harker, E. S. Laird, M. J. Page
Comments: 20 pages, 14 figures, accepted for publication in MNRAS

It is starbursts.

Model analysis of the very high energy detections of the starburst galaxies M82 and NGC 253

E. de Cea del Pozo, D. F. Torres, A. Y. Rodriguez, O. Reimer, arXiv:0912.3497 [ps, pdf, other]
Comments: 6 pages, 3 figures, 2 tables, 2009 Fermi Symposium, eConf Proceedings C091122

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Black Holes and AGN

The Geometry of Mass Outflows and Fueling Flows in the Seyfert 2 Galaxy Mrk 3
D.M. Crenshaw, S.B. Kraemer, H.R. Schmitt, Y.L. Jaffe, R.P. Deo, N.R. Collins, T.C. Fischer, arXiv:0912.2420 [ps, pdf, other]
Comments: 22 page, 7 figures, accepted for publication in the Astronomical Journal

Their abstract: We present a study of the resolved emission-line regions and an inner dust/gas disk in the Seyfert 2 galaxy Mrk 3, based on Hubble Space Telescope observations. We show that the extended narrow-line region (ENLR), spanning ~4 kpc, is defined by the intersection of the ionizing bicone of radiation from the AGN and the inner disk, which is not coplanar with the large-scale stellar disk. This intersection leads to different position and opening angles of the ENLR compared to the narrow-line region (NLR). A number of emission-line arcs in the ENLR appear to be continuations of dust lanes in the disk, supporting this geometry. The NLR, which consists of outflowing emission-line knots spanning the central ~650 pc, is in the shape of a backwards S. This shape may arise from rotation of the gas, or it may trace the original fueling flow close to the nucleus that was ionized after the AGN turned on."

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Stars, Supernovae and Planets

OB Stars & Stellar Bowshocks in Cygnus-X: A Novel Laboratory Estimating Stellar Mass Loss Rates
Henry A. Kobulnicky, Ian J. Gilbert, Daniel C. Kiminki, arXiv:0912.1314 [ps, pdf, other]
Comments: 49 pages, 19 figures; Accepted for publication in ApJ; full-resolution color figure version available at this http URL; comments invited

CoRoT-7 b: Super-Earth or Super-Io?
Rory Barnes, Sean N. Raymond, Richard Greenberg, Brian Jackson, Nathan A. Kaib, arXiv:0912.1337 [ps, pdf, other]
Comments: 13 pages, 3 figures, accepted to ApJ Letters

The simultaneous formation of massive stars and stellar clusters
Rowan J. Smith, Steven Longmore and Ian Bonnell, 2009, MNRAS, 400, 1775
Full Text: HTML, PDF (Size: 20619K)

Updated stellar yields from Asymptotic Giant Branch models
Amanda I. Karakas, arXiv:0912.2142 [ps, pdf, other]
Comments: Accepted for publication in MNRAS; 15 pages

New 3-D gas density maps of NaI and CaII interstellar absorption within 300pc
Barry Y. Welsh, Rosine Lallement, Jean-Luc Vergely, Severine Raimond, arXiv:0912.3040 [ps, pdf, other]
Comments: A&amp;A accepted

The NaI and CaII distributions are quite different. A very impressive piece of work.

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Numerical Methods and Theoretical Astrophysics

Astrophysical turbulence
Axel Brandenburg, Aake Nordlund, arXiv:0912.1340 [ps, pdf, other]

Comments: 80 pages, 24 figures, submitted to Reports on Progress in Physics. For higher figure quality and more frequent revisions see this http URL

Detailed Decomposition of Galaxy Images. II. Beyond Axisymmetric Models
Chien Y. Peng, Luis C. Ho, Chris D. Impey, Hans-Walter Rix, arXiv:0912.0731 [ps, pdf, other]

Comments: 41 pages, 22 figures, AJ submitted. Comments welcomed. Full resolution version of this paper is available at: this http URL

Dynamical Models for the Formation of Elephant Trunks in H II Regions
Jonathan Mackey, Andrew J. Lim, arXiv:0912.1499 [ps, pdf, other]

Comments: 19 pages, 11 figures, accepted for publication in MNRAS. Version with high resolution figures available at this http URL

Interesting Astrophysics: Oct 12 to Oct 23

This edition of Interesting Astrophysics spans an even wide range of topics than normal, from C IV in the IGM (D'Odorico et al), X-ray emission from galaxies (Laird et al, Pietsch), a variety of supernova-related preprints, to AGN feedback/outflows and other topics I've not mentioned.

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Galaxies and Starbursts

An Anisotropic Propagation Model for Galactic Cosmic Rays
Iris Gebauer, Wim de Boer, arXiv:0910.2027 [ps, pdf, other]
Comments: 19 pages, 19 figures, submitted to A&amp;A

The rise of the C IV mass density at z<2.5
Valentina D'Odorico, Francesco Calura, Stefano Cristiani, Matteo Viel, arXiv:0910.2126 [ps, pdf, other]
Comments: Paper accepted by MNRAS. The parameters of the C IV line fitting will be available in electronic format

The radial distribution of core-collapse supernovae in spiral host galaxies
A. A. Hakobyan, G. A. Mamon, A. R. Petrosian, D. Kunth, M. Turatto, arXiv:0910.1801 [ps, pdf, other]
Comments: 10 pages, 6 figures, 5 tables. Astronomy &amp; Astrophysics, in press

On the X-ray properties of submm-selected galaxies
Elise S. Laird, Kirpal Nandra, Alexandra Pope, Douglas Scott, arXiv:0910.2464 [ps, pdf, other]
Comments: 12 pages, 5 figures, accepted for publication in MNRAS

X-ray emission from optical novae in M 31
W. Pietsch, arXiv:0910.3865 [ps, pdf, other]
Comments: 6 pages, 4 figures, accepted for publication in Aston.Nachr

Bars in Starbursts and AGNs -- A Quantitative Reexamination
Lei Hao, Shardha Jogee, Fabio D. Barazza, Irina Marinova, Juntai Shen, arXiv:0910.3960 [ps, pdf, other]
Comments: 8 pages, 3 figures, to be published in "Galaxy Evolution: Emerging Insights and Future Challenges", ed. S. Jogee et al., Astron. Soc. Pacific, 2009

From their abstract: "We find that AGN and star-forming galaxies have similar optical bar fractions, 47% and 50%, respectively. Both bar fractions are higher than that in inactive galaxies (29%)."

Extragalactic CS survey
E. Bayet, R. Aladro, S. Martin, S. Viti, J. Martin-Pintado, arXiv:0910.4282 [pdf, other]
Comments: 17 pages, 16 figures, 3 tables, Accepted to ApJ

From the abstract: "We present a coherent and homogeneous multi-line study of the CS molecule in nearby (D$<$10Mpc) galaxies. We include, from the literature, all the available observations from the $J=1-0$ to the $J=7-6$ transitions towards NGC 253, NGC 1068, IC 342, Henize~2-10, M~82, the Antennae Galaxies and M~83."

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Black Holes and AGN

Feeding and Feedback in nearby AGN from Integral Field Spectroscopy
Thaisa Storchi-Bergmann, arXiv:0910.3234 [ps, pdf, other]
Comments: 4 pages, 2 figures, to appear in the proceedings of the conference "The Monster's Fiery Breath", eds. Sebastian Heinz and Eric Wilcots

From the abstract: "The ionized gas, on the other hand, traces the AGN feedback. Its
kinematics shows two components: (1) one originating in the plane, and
dominated by circular rotation; (2) another outflowing along the Narrow-Line
Region (NLR) whose flux distribution and kinematics frequently correlate with
structures seen in radio maps. Mass outflow rates along the NLR range from
10^-2 to 1 M_sun yr^-1, corresponding to 10-100 times the accretion rate to the
AGN, indicating that most of the NLR gas mass has been entrained from the
galaxy plane. The average kinetic power of the NLR outflows is ~10^-4 times the
bolometric luminosity.
"

AGN Feedback: Does it work?
Smita Mathur, Rebecca Stoll, Yair Krongold, Fabrizio Nicastro, Nancy Brickhouse, Martin Elvis, arXiv:0910.3691 [ps, pdf, other]
Comments: to appear in proceedings of the conference "The Monster's Fiery Breath: Feedback in Galaxies, Groups, and Clusters", June 2009, Madison, WI, Eds. S. Heinz &amp; E. Wilcots

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Interstellar Medium

PAH processing in interstellar shocks
E. R. Micelotta, A. P. Jones, A. G. G. M. Tielens, arXiv:0910.2461 [ps, pdf, other]
Comments: 21 pages, 11 figures, accepted for publication in Astronomy and Astrophysics

VLT/FLAMES-ARGUS observations of stellar wind--ISM cloud interactions in NGC 6357
M.S. Westmoquette, J.D. Slavin, L.J. Smith, J.S. Gallagher III, arXiv:0910.4191 [ps, pdf, other]
Comments: 9 pages, 5 figures (3 colour). Accepted for publication in MNRAS

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Stars, Supernovae and Planets

The rebrightening of planetary nebulae through ISM interaction

C J Wareing, arXiv:0910.2200 [ps, pdf, other]

Comments: Review paper accepted to PASA. 8 pages, 5 figures. High resolution images available from the author

Stellar Feedback in Molecular Clouds and its Influence on the Mass Function of Young Star Clusters
S. Michael Fall, Mark R. Krumholz, Christopher D. Matzner, arXiv:0910.2238 [ps, pdf, other]
Comments: 5 pages, 2 figures, emulateapj format, submitted to ApJL

Typing Supernova Remnants Using X-ray Line Emission Morphologies
Laura A. Lopez, Enrico Ramirez-Ruiz, Carles Badenes, Daniela Huppenkothen, Tesla E. Jeltema, David A. Pooley, arXiv:0910.3208 [ps, pdf, other]
Comments: 4 pages, 1 figure, accepted for publication in ApJL

Line-of-sight Shell Structure of the Cygnus Loop
Hiroyuki Uchida, Hiroshi Tsunemi, Satoru Katsuda, Masashi Kimura, Hiroko Kosugi, Hiroaki Takahashi, arXiv:0910.3731 [ps, pdf, other]
Comments: 8 pages, 7 figures, accepted for publication in ApJ
Journal-ref: Astrophysical Journal 705 (2009) 1152-1159

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Other

FISH: A 3D parallel MHD code for astrophysical applications
R. Kaeppeli, S. C. Whitehouse, S. Scheidegger, U.-L. Pen, M. Liebendoerfer, arXiv:0910.2854 [ps, pdf, other]
Comments: 27 pages, 11 figures

Astrometry.net: Blind astrometric calibration of arbitrary astronomical images
Dustin Lang, David W. Hogg, Keir Mierle, Michael Blanton, Sam Roweis, arXiv:0910.2233 [pdf, other]
Comments: submitted to AJ

A very cool idea!

Interesting Astrophysics: Jul 01 to Jul 13

A quiet few weeks from on the astrophysical journals and arXiv.

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Galaxies and Starbursts

Confirming a Population of Hot-Dust Dominated, Star Forming Ultraluminous Galaxies at High-Redshift
C.M. Casey, S.C. Chapman, R.J. Beswick, A.D. Biggs, A.W. Blain, L.J. Hainline, R.J. Ivison, T. Muxlow, I. Smail, arXiv:0906.5346 [ps, pdf, other]
Comments: 9 pages, 6 figures; accepted for publication in MNRAS

The Disruption of Giant Molecular Clouds by Radiation Pressure and the Efficiency of Star Formation in Galaxies
Norman Murray, Eliot Quataert, Todd A. Thompson, arXiv:0906.5358 [ps, pdf, other]
Comments: 17 pages, 5 figures, submitted to ApJ

The New Frontier: Galactic-Scale Star Formation
Daniela Calzetti, Robert C. Kennicutt, arXiv:0907.0203 [ps, pdf, other]
Comments: accepted for publication on PASP, short review for the IYA2009, 12 pages, no figures

The age of blue LSB galaxies
E. I. Vorobyov, Yu. Shchekinov, D. Bizyaev, D. Bomans, R.-J. Dettmar, arXiv:0907.0830 [ps, pdf, other]
Comments: Accepted for publication in Astronomy and Astrophysics

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Black Holes and AGN

The Infrared Nuclear Emission of Seyfert Galaxies on Parsec Scales: Testing the Clumpy Torus models
Cristina Ramos Almeida, Nancy A. Levenson, Jose Miguel Rodriguez Espinosa, Almudena Alonso Herrero, Andres Asensio Ramos, James T. Radomski, Chris Packham, R. Scott Fisher, Charles M. Telesco, arXiv:0906.5368 [ps, pdf, other]
Comments: 26 pages, 8 figures, 9 tables. Accepted for publication in ApJ

Their sample is Centaurus A, Circinus, IC 5063, Mrk 573, NGC 1386, NGC 1808, NGC 3081, NGC 3281, NGC 4388, NGC 5728, NGC 7172, NGC 7582, NGC 1365, NGC 2992, NGC 5506, NGC 3227, NGC, 4151, NGC 1566.

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Instrumentation

Analytical computation of the off-axis Effective Area of grazing incidence X-ray mirrors
D. Spiga, V. Cotroneo, S. Basso, P. Conconi, arXiv:0906.5367 [ps, pdf, other]
Comments: 12 pages, 11 figures, accepted for publication in "Astronomy &amp; Astrophysics", section "Instruments, observational techniques, and data processing"

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Numerical Astrophysics and Hydrodynamics

Two-dimensional AMR simulations of colliding flows
Markus Niklaus, Wolfram Schmidt, Jens C. Niemeyer, arXiv:0907.1239 [pdf, other]
Comments: 6 pages, 6 figures, submitted to A&A

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Stars and Supernovae

Comparisons of the radial distributions of core-collapse supernovae with those of young and old stellar populations
J. P. Anderson, P. A. James, arXiv:0907.0034 [ps, pdf, other]
Comments: Accepted for publication in MNRAS

Predicted gamma-ray image of SN 1006 due to inverse Compton emission
O.Petruk, F.Bocchino, M.Miceli, G.Dubner, G.Castelletti, S.Orlando, D.Iakubovskyi, I.Telezhinsky, arXiv:0907.0976 [ps, pdf, other]
Comments: 10 pages, 11 figures, accepted in MNRAS

Interesting Astrophysics: Mar 16 to Mar 20

An unusually large crop of interesting star/supernova/star cluster related preprints attracted my attention this week. From the largest (radius) star in the LMC through photon-tiring in radiation driven winds, super-hard X-ray emission from Eta Carinae, to an anomaly with the classic wind-blown bubble, the "Bubble Nebula."

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Galaxies and Starbursts

The Relationship Between Intergalactic HI/OVI and Nearby (z<0.017) Galaxies
B.P. Wakker, B.D. Savage, arXiv:0903.2259 [ps, pdf, other]
Comments: ApJ Supplement, in press

On the massive star content of the nearby dwarf irregular Wolf-Rayet galaxy IC 4662
P.A. Crowther, J.L. Bibby, arXiv:0903.2288 [ps, pdf, other]
Comments: 10 pages, 4 figures, accepted for Astronomy & Astrophysics

The Vela Cloud: A Giant HI Anomaly in the NGC 3256 Group
Jayanne English, Baerbel Koribalski, Joss Bland-Hawthorn, Ken Freeman, Claudia McCain, arXiv:0903.2690 [ps, pdf, other]
Comments: 46 pages, 11 figures, submitted to AJ

The chemical evolution of galaxies within the IGIMF theory: the [alpha/Fe] ratios and downsizing
Simone Recchi, Francesco Calura, Pavel Kroupa, arXiv:0903.2395 [ps, pdf, other]
Comments: 13 pages, 18 figures, accepted for publication in Astronomy and Astrophysics

The Star Formation Law at Low Surface Density
Ted K. Wyder, et al, arXiv:0903.3015 [ps, pdf, other]
Comments: 53 pages, 21 Figures, accepted for publication in the ApJ

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Black Holes and AGN

X-ray Properties of Intermediate-Mass Black Holes in Active Galaxies. II. X-ray-Bright Accretion and Possible Evidence for Slim Disks
Louis-Benoit Desroches, Jenny E. Greene, Luis C. Ho, arXiv:0903.2257 [ps, pdf, other]
Comments: 11 pages, 6 figures, submitted to ApJ, emulateapj

The Suzaku View of the Swift/BAT AGNs (II): Time Variability and Spectra of Five "Hidden" AGNs
Lisa Winter, Richard Mushotzky, Yuichi Terashima, Yoshihiro Ueda, arXiv:0903.2802 [ps, pdf, other]
Comments: 45 pages, 16 figures, 10 tables, accepted to ApJ

Journey to the $M_{\rm BH} - \sigma$ relation: the fate of low mass black holes in the Universe
Marta Volonteri, Priyamvada Natarajan, arXiv:0903.2262 [pdf, other]
Comments: 8 pages, 5 figures, submitted to MNRAS

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Numerical Astrophysics and Hydrodynamics

Simulating Magnetohydrodynamical Flow with Constrained Transport and Adaptive Mesh Refinement; Algorithms & Tests of the AstroBEAR Code
Andrew J. Cunningham, Adam Frank, Peggy Varniere, Sorin Mitran, Thomas W. Jones, arXiv:0710.0424 (replaced) [ps, pdf, other]
Comments: Additional Tests shown. Accepted to ApJS

Includes some images showing the interaction between a cylindrical cloud moving though an ambient medium with a magnetic field oriented in various directions w.r.t the cloud motion. B fields at 45 or 90 degree to the cloud motion/axis lead to less cloud disruption than if the B field is parallel to the cloud axis/motion.

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Stars, Supernovae and Planets

The Physical Properties of the Red Supergiant WOH G64: The Largest Star Known?
Emily M. Levesque, Philip Massey, Bertrand Plez, Knut A. G. Olsen, arXiv:0903.2260 [ps, pdf, other]
Comments: 25 pages, 5 figures; accepted for publication in The Astronomical Journal

Super-hard X-Ray Emission from eta Carinae Observed with Suzaku
Akiko Sekiguchi, Masahiro Tsujimoto, Shunji Kitamoto, Manabu Ishida, Kenji Hamaguchi, Hideyuki Mori, Yohko Tsuboi, arXiv:0903.3307 [ps, pdf, other]
Comments: Accepted for publication in PASJ (10 pages, 7 Postscript figures)

Interestingly they argue that the 15-50 keV emission is either Inverse Compton emission arising between stellar UV photons and non-thermal electrons "or to the thermal bremsstrahlung of very hot plasma, and not to the bremsstrahlung by non-thermal electrons colliding with cold ambient matter."

On the behaviour of stellar winds that exceed the photon-tiring limit
Allard Jan van Marle, Stanley P. Owocki, Nir J. Shaviv, MNRAS, 2009, 394, 595
Full Text: HTML, PDF (Size: 9132K)

A steady-state continuum radiation-driven wind not have a mechanical luminosity exceeding the radiative luminosity at its base (the photon tiring limit). This paper explores non-steady state winds beyond the photon tiring limit. Interesting also w.r.t radiation-driven winds from AGN perhaps?

Unsolved Problems about Supernovae
Nino Panagia, arXiv:0903.3378 [ps, pdf, other]
Comments: 7 pages, Proceedings of 'Probing Stellar Populations out to the Distant Universe', Cefalu, Italy, Sep 7-19, 2008, AIP Conf. Proc. Series

Three-dimensional numerical model of the Omega Nebula (M17): simulated thermal X-ray emission
J. Reyes-Iturbide, P. F. Velázquez, M. Rosado, A. Rodríguez-González, R. F. González, A. Esquivel, 2009, MNRAS, 394, 1009
Full Text: HTML, PDF (Size: 4758K)

Study of Bubble Nebula using IUE high resolution Spectra
M. Y. Anand, B. A. I Kagali, Jayant Murthy, arXiv:0903.2828 [ps, pdf, other]
Comments: 9 pages, 6 figures, accepted in BASI

Interesting. Yet another expansion velocity - bubble size - stellar age anomaly, and this time in a spherical bubble around a main sequence star that really should follow the Weaver bubble model. The dynamical age of a wind blown bubble t_bub = 0.6*R_bub/v_bub, in this case ~3e4 years, which is much smaller than the age of the main sequence O star thought to have blown the bubble (~2e6 years). Yet the expansion velocity of v_bub ~ 36 km/s is high enough that there is no reason to suspect the bubble has stalled, and its near perfect shape does not suggest irregular expansion.

What fuels star formation in galaxies? (part 2)

How do Galaxies fuel Star Formation? Where do they get the gas that forms new stars?

Back when I started this blog in 2006 I had a short post discussing the issue of where galaxies got the gas they use to fuel ongoing star formation from, which was meant to lead onto the discussion of a paper by Keres et al. (I never got around to discussing that paper.)

Star formation requires interstellar gas (specifically cold dense molecular gas), ... (a) where does the gas come from, and (b) what controls the star formation rate in a galaxy with a given amount of gas?

The old view (say in the 1980's era) was that galaxies accumulated the baryonic matter (in the form of neutral gas or an ionized plasma) into the center of the gravitational potential well (dominated by Dark Matter) they were forming within via dissipative processes (collision and radiation), and this essentially comprised their total gas budget for the rest of the life of the galaxy. Rapid collapse of the gas to the center of the potential well (within a dynamical time) created elliptical galaxies, whereas slower (less dissipative) accretion preserved angular momentum and led to the formation of rotation-support disk galaxies (i.e. spiral galaxies). Star formation rates in galaxies decreased with time exponentially (e.g. if you convert a fixed fraction e_SF of your total gas budget to stars in every galactic rotation you get an exponential decrease in gas mass with a e-folding time constant 1/e_SF).

So galaxies are just running down in this view, sooner or later running out of gas and becoming "red and dead", i.e. like ellipticals which presumably ran out of gas first.

The more modern viewpoint is to account for continued accretion of fresh intergalactic gas into the gravitational potential wells of galaxies. Differences between red (dead) and blue (actively star forming) galaxies may be in the character of the ongoing accretion process. If that accretion process changes your galaxy can change its type.

Gas falling into the potential well of massive galaxies gains enough gravitational potential energy to reach a velocity where the shock wave it encounters when hitting other gas heats it to X-ray emitting temperatures. At such temperatures the cooling time is long, so it has trouble losing enough energy to fall to the center of the potential well and end up in the galaxy. Instead it forms a hot but tenuous halo of gas surrounding the galaxy. So with decreased dissipation the gas has trouble fueling any star formation in the massive galaxy. Conversely the gas falling into the potential well of a lower mass galaxy is either never shocked, or if shock heated it only achieves temperatures where cooling is rapid (T < 10⁶ K). So it dissipates its energy easily and falls into the galaxy at the center of the gravitational potential well, and is available to fuel additional star formation in this lower mass galaxy. Massive galaxies are predominantly ellipticals or low SF rate spirals, while actively star forming galaxies are typically lower mass galaxies, so the distinction between the different models of star formation in spiral versus elliptical galaxies is preserved but explained in a different manner (nature, rather than initial nurture, as it were).

Indeed, some would argue that the current star formation rate of a galaxy must closely matches its current accretion rate. This raises the question of whether enough gas is falling onto our own Galaxy to account for our star formation rate of 1-3 Solar masses per year. Again this is very different from the old picture of SF in galaxies where you started off with a fixed mass of gas and just consumed it until you run out.

The preceding discussion is only a crude cartoon view of the subject, but serves to introduce the subject. I brought this subject up again because I noticed one of the Astro2010 Decadal Survey White Papers is on the subject of where galaxies get their gas and how do they turn that gas into stars.

If you are interested in seeing what the latest state-of-the-art in this subject is, and where people who actually work on this subject would like to see it go, then please read

How do Galaxies Accrete Gas and Form Stars? by M.E. Putman, et al, arXiv:0902.4717 [ps, pdf, other].

It is written for an audience of professional astrophysicists, but their is content that an educated and interested layperson can benefit from.

Interesting Astrophysics: Feb 16 to Feb 19

Another collection of interesting papers and preprints. Quite a lot of potentially interesting stuff this week, from the galaxy mass versus effective yield relationship at redshift z~3 to the effect of nearby historical supernova on Earth's atmosphere, along with tons of Spitzer observations of galaxies and AGN and a possible stellar disruption event.

I plan on doing a separate list of what I consider to be the most interesting White Papers submitted to the Astro2010 Decadal Survey and were also posted for public consumption on arXiv's astro-ph preprint service. I'll post that once it appears that posting of White Papers to arXiv is tailing off.

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Galaxies and Starbursts

The present-day galaxy population in spiral galaxies
Reynier Peletier, arXiv:0902.2279 [ps, pdf, other]

Comments: 8 pages, Proceedings of 'Probing Stellar Populations out to the Distant Universe', Cefalu, Italy, Sep 7-19, 2008, AIP Conf. Proc. Series. Higher resolution version available at this http URL

Estimating the H I gas fractions of galaxies in the local Universe
Wei Zhang, Cheng Li, Guinevere Kauffmann, Hu Zou, Barbara Catinella, Shiyin Shen, Qi Guo, Ruixiang Chang, arXiv:0902.2392 [ps, pdf, other]
Comments: 11 pages, 8 figures, submitted for publication in MNRAS

Gas-poor galaxies do have higher gas-phase abundances than (less evolved) gas rich galaxies. Interesting. Compares to semi-analytic models, but the devil lies in the details of the recipe used for supernova feedback in the SAMs.

LSD: Lyman-break galaxies Stellar populations and Dynamics. I: Mass, metallicity and gas at z~3.1
F. Mannucci, G. Cresci, R. Maiolino, A. Marconi, G. Pastorini, L. Pozzetti, A. Gnerucci, G. Risaliti, R. Schneider, M. Lehnert, M. Salvati, arXiv:0902.2398 [ps, pdf, other]
Comments: submitted to MNRAS

Surprisingly find that effective yields are lower in the more massive galaxies, and approach Solar at the low mass end of the sample. Unsurprisingly they end up requiring gas accretion to be more effective in the most massive galaxies in order to explain this. This is totally reversed from the local galaxy M-y_eff relationship. Is this consistent the other estimates of M-Z relationship at z > 2?

Physical conditions in the ISM of intensely star-forming galaxies at redshift~2
M. D. Lehnert, N. P. H. Nesvadba, L. Le Tiran, P. Di Matteo, W. van Driel, L. S. Douglas, L. Chemin, F. Bournaud, arXiv:0902.2784 [ps, pdf, other]
Comments: ApJ accepted main journal, 21 pages, 12 figures

Bulges Of Nearby Galaxies With Spitzer: The Growth Of Pseudobulges In Disk Galaxies And Its Connection To Outer Disks
David B. Fisher, Niv Drory, Maximilian H. Fabricius, arXiv:0902.3258 [ps, pdf, other]
Comments: Accepted to ApJ

From the abstract: "In almost all galaxies in our sample the specific SFR (SFR per unit stellar mass) of the bulge is higher than that of the outer disk, suggesting that almost all galaxies are increasing their B/T through internal star formation."

The First Galaxies: Signatures of the Initial Starburst
Jarrett L. Johnson, Thomas H. Greif, Volker Bromm, Ralf S. Klessen, Joseph Ippolito, arXiv:0902.3263 [ps, pdf, other]
Comments: 11 pages, 10 figures; to be submitted to MNRAS

The Radio Luminosity Function and Galaxy Evolution in the Coma Cluster
Neal A. Miller, Ann E. Hornschemeier, Bahram Mobasher, Terry J. Bridges, Michael J. Hudson, Ronald O. Marzke, Russell J. Smith, arXiv:0902.3388 [ps, pdf, other]
Comments: 45 pages with 13 figures, accepted for publication in AJ

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Black Holes and AGN

Mass Outflow in the Seyfert 1 Galaxy NGC 5548
D.M. Crenshaw, S.B. Kraemer, H.R. Schmitt, J.S. Kaastra, N. Arav, J.R. Gabel, K.T. Korista, arXiv:0902.2310 [ps, pdf, other]
Comments: 39 pages, 11 figures, accepted for publication in the Astrophysical Journal

AGN–starburst connection in NGC 7582: Gemini near-infrared spectrograph integral field unit observations (p 783-797)
Rogemar A. Riffel, Thaisa Storchi-Bergmann, Oli L. Dors Jr, Cláudia Winge, 2009, MNRAS, 393, 783
Full Text: HTML, PDF (Size: 3067K)

Resolving the mid-infrared cores of local Seyferts
P. Gandhi, H. Horst, A. Smette, S. Hoenig, A. Comastri, R. Gilli, C. Vignali, W. Duschl, arXiv:0902.2777 [ps, pdf, other]
Comments: Accepted for publication in Astronomy & Astrophysics

Spitzer spectra of Seyfert galaxies
Luigi Spinoglio, Silvia Tommasin, Matthew A. Malkan, Kevin Hainline, arXiv:0902.3341 [ps, pdf, other]
Comments: to appear in the proceedings of "The Starburst-AGN Connection Conference", Shanghai, China, 27 Oct - 1 Nov 2008, ASP Conference Series

Mid-infrared spectroscopy of infrared-luminous galaxies at z~0.5-3
A. Hernan-Caballero, I. Perez-Fournon, E. Hatziminaoglou, A. Afonso-Luis, M. Rowan-Robinson, D. Rigopoulou, D. Farrah, C. J. Lonsdale, T. Babbedge, D. Clements, S. Serjeant, F. Pozzi, M. Vaccari, F. M. Montenegro-Montes, I. Valtchanov, E. Gonzalez-Solares, S. Oliver, D. Shupe, C. Gruppioni, B. Vila-Vilaro, C. Lari, F. La Franca, arXiv:0902.3369 [ps, pdf, other]
Comments: 32 pages, 24 figures, 15 tables, accepted for publication in MNRAS

NTT, Spitzer and Chandra spectroscopy of SDSSJ095209.56+214313.3: the most luminous coronal-line supernova ever observed, or a stellar tidal disruption event ?
S. Komossa, H. Zhou, A. Rau, M. Dopita, A. Gal-Yam, J. Greiner, J. Zuther, M. Salvato, D. Xu, H. Lu, R. Saxton, M. Ajello, arXiv:0902.3248 [ps, pdf, other]
Comments: 18 pages, 8 (colour) figures; submitted to ApJ

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X-rays

Spectral States and Evolution of Ultraluminous X-ray Sources
Hua Feng, Philip Kaaret, arXiv:0902.2607 [ps, pdf, other]
Comments: 17 pages, 9 tables, 10 figures, accepted by ApJ

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Cosmology, in particular numerical cosmology

Probing recent star formation with absorption-line strengths in hierarchical models and observations
S.C. Trager, R.S. Somerville, arXiv:0902.2336 [ps, pdf, other]
Comments: Accepted for publication in Monthly Notices of the Royal Astronomical Society. 17 pages

Cosmological formation and chemical evolution of an elliptical galaxy
E. Colavitti, A. Pipino, F. Matteucci, arXiv:0902.2768 [ps, pdf, other]
Comments: 8 pages, 6 figures, accepted for publication by A&A

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Numerical Astrophysics and Hydrodynamics

Cosmological AMR MHD with Enzo
David C. Collins, Hao Xu, Michael L. Norman, Hui Li, Shengtai Li, arXiv:0902.2594 [ps, pdf, other]
Comments: 56 pages, 26 figures, submitted to the Astrophysical Journal Suppliments

Galaxy Mergers with Adaptive Mesh Refinement: Star Formation and Hot Gas Outflow
Ji-hoon Kim, John H. Wise, Tom Abel, arXiv:0902.3001 [ps, pdf, other]

Comments: 4 pages, 5 figures, Accepted for publication in the Astrophysical Journal Letters, Image resolution greatly reduced, High-resolution version of this article and movies are available at this http URL

Interesting, but hardly deserves to be a Letter given that they're probably going to do a full paper as well.

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Stars, Supernovae and Planets

An Antarctic ice core recording both supernovae and solar cycles
Yuko Motizuki, Kazuya Takahashi, Kazuo Makishima, Aya Bamba, Yoichi Nakai, Yasushige Yano, Makoto Igarashi, Hideaki Motoyama, Kokichi Kamiyama, Keisuke Suzuki, Takashi Imamura, arXiv:0902.3446 [pdf]
Comments: 18 pages, 5 figures, submitted to Nature

Pretty amazing stuff, although prior attempts at this sort of thing were not robust. From the text: "When a SN explodes close to the earth, the nuclear γ-rays produced (~0.1–1 MeV)
can lead to an enhancement of nitrogen oxide production in the middle atmosphere or
the stratosphere. SN events could therefore be traced in ice cores as NO₃^– concentration spikes."

The Secret XUV Lives of Cepheids: FUV/X-ray Observations of Polaris and beta Dor
Scott G. Engle, Edward F. Guinan, Joseph DePasquale, Nancy Evans, arXiv:0902.3449 [ps, pdf, other]
Comments: 6 pages, 1 figure, to appear in the proceedings of the "Future Directions in Ultraviolet Spectroscopy" Meeting - October 20-22, 2008; Annapolis, Maryland, USA

The Physical Properties of Red Supergiants
Emily M. Levesque, arXiv:0902.2789 [ps, pdf, other]
Comments: 10 pages, 2 figures; to appear in proceedings of "Hot and Cool: Bridging Gaps in Massive Star Evolution"