Monday, March 22, 2010

Interesting Astrophysics: Mar 08 to Mar 22

I return from a much-needed holiday in the Caribbean to an energetic bunch of preprints and papers making its appearance in this edition of Interesting Astrophysics.

Galactic winds, including possible AGN-driven galactic winds, are of course my major interest, so Scannapieco & Brüggen's paper is of particular note, but note also Dadina et al, Shu et al (twice) and Jiménez-Vicente et al's papers.

X-ray emission from star forming galaxies also makes an appearance, with Wang's PNAS review, Owen & Warwick's XMM-Newton study of M33, and Anderson & Bregman's discussion of the baryon content of hot halos around galaxies. Martin Weisskopf's history of the project to build the Chandra X-ray Observatory is also well worth reading.

Galaxies and Starbursts

X-raying Galaxies: A Chandra Legacy
Q. Daniel Wang, arXiv:1003.1282 [pdf, other]
Comments: Refereed review article to be published in Proceedings of the National Academy of Sciences

The submillimetre properties of ultraluminous infrared galaxies
D. L. Clements, L. Dunne, S. Eales, 2010, MNRAS, 403, 274
Full Text: HTML, PDF (Size: 859K)

A blue tilt in the globular cluster system of the Milky Way-like galaxy NGC 5170
Duncan A. Forbes, Lee R. Spitler, W. E. Harris, Jeremy Bailin, Jay Strader, Jean P. Brodie, S. S. Larsen, 2010, MNRAS, 403, 429
Full Text: HTML, PDF (Size: 3707K)

The likeness of a galaxy to the Milky-Way often depends greatly on whose opinion you ask. NGC 5170 has a circular rotation velocity of ~250 km/s and a star formation rate of ~0.5 Solar masses per year, making it somewhat more massive and less active than the Milky Way. Nevertheless an interesting galaxy (No X-ray halo was detected around NGC 5170 in Chandra observations, see Pedersen et al 2006 and Rasmussen et al 2009. Note that the detection of an X-ray halo around NGC 5746 claimed in Pedersen et all 2006 was effectively retracted by Rasmussen et al 2009).

Ongoing Star Formation In AGN Host Galaxy Disks: A View From Core-collapse Supernovae
J. Wang, J. S. Deng, J. Y. Wei, arXiv:1003.1358 [ps, pdf, other]
Comments: 5 pages, 4 figures, accepted by MNRAS

A Region of Violent Star Formation in the Irr Galaxy IC 10: Structure and Kinematics of Ionized and Neutral Gas
O. V. Egorov, T. A. Lozinskaya, A. V. Moiseev, arXiv:1003.1705 [ps, pdf, other]
Comments: 22 pages, 10 figures; accepted in Astronomy Reports

Do Hot Haloes Around Galaxies Contain the Missing Baryons?
Michael E. Anderson, Joel N. Bregman, arXiv:1003.3273 [ps, pdf, other]
Comments: accepted for publication in the Astrophysical Journal

As with most papers that pose a question in their title, the answer is no. A nice paper worth looking at.

On The GeV & TeV Detections of the Starburst Galaxies M82 & NGC 253
Brian C. Lacki, Todd A. Thompson, Eliot Quataert, Abraham Loeb, Eli Waxman, arXiv:1003.3257 [ps, pdf, other]
Comments: 14 pages, emulateapj format, submitted to ApJ.

Black Holes and AGN

X-ray imaging of the ionisation cones in NGC 5252
M.Dadina, M.Guainazzi, M.Cappi, S.Bianchi, C. Vignali, G. Malaguti, A. Comastri, rXiv:1003.1665 [ps, pdf, other]
Comments: Accepted for publication in A&A

NGC 2992 in an X-ray high state observed by XMM: Response of the Relativistic Fe K$\alpha$ Line to the Continuum
X. W. Shu, T. Yaqoob, K. D. Murphy, V. Braito, J. X. Wang, W. Zheng, arXiv:1003.1789 [ps, pdf, other]
Comments: 30 pages, 6 figures, Accepted to ApJ

The Cores of the Fe Kα Lines in Active Galactic Nuclei: an Extended Chandra High Energy Grating Sample
X. W. Shu, T. Yaqoob, J. X. Wang, arXiv:1003.1790 [ps, pdf, other]
Comments: 54 pages, 7 figures, and 4 tables, to appear in ApJ Supplement Series

Blasts and shocks in the disc of NGC 4258
J. Jiménez-Vicente, E. Mediavilla, A. Castillo-Morales, E. Battaner, arXiv:1003.3635 [ps, pdf, other]
Comments: 7 pages, 10 colour figures. Accepted for publication in MNRAS.

Na I observations with an IFU.

Numerical Methods

General two-dimensional least-squares image subtraction
J. L. Quinn, A. Clocchiatti and M. Hamuy, 2010, MNRAS, 403, L1
Full Text: HTML, PDF (Size: 514K)

Shape: A 3D Modeling Tool for Astrophysics
Wolfgang Steffen, Nicholas Koning, Stephan Wenger, Christophe Morisset, Marcus Magnor, arXiv:1003.2012 [pdf, other]
Comments: 13 pages, 11 figures, accepted for publication in the "IEEE Transactions on Visualization and Computer Graphics"

Simulating Supersonic Turbulence in Galaxy Outflows
Evan Scannapieco, Marcus Brüggen, arXiv:1003.3234 [pdf, other]
Comments: 22 pages, 13 figures, MNRAS, in press


Innovations in the Analysis of Chandra-ACIS Observations
Patrick S. Broos, Leisa K. Townsley, Eric D. Feigelson, Konstantin V. Getman, Franz E. Bauer, Gordon P. Garmire, arXiv:1003.2397 [pdf, other]
Comments: Accepted by the ApJ, 2010 Mar 10, 39 pages, 16 figures

The Making of the Chandra X-ray Observatory: the Project Scientist's Perspective
Martin C. Weisskopf, arXiv:1003.1990 [pdf]
Comments: 6 pages, 17 figures. To be published in the Proceedings of the national Academy of Sciences of the United States of America.

I found this to be a really interesting article. It discusses both technical and political development with a sprinkling of dry humor. Also note the time span between the conceptual birth of AXAF/Chandra (1963, and the updated 1976 proposal) and the actual launch in 1999.

Soft X-ray emission from the inner disc of M33
R. A. Owen and R. S. Warwick, 2010, MNRAS, 403, 558
Full Text: HTML, PDF (Size: 4702K)

Monday, March 08, 2010

Thanks, but I'm not worthy (Research Blogging Awards)

Wow! Somehow this blog got into the finalist list for Research Blogging's best research blog of 2010.

I'm deeply flattered - thank you.

But seriously, my little part-time blog isn't anywhere near the quality of the other blogs on the nominee list.

I voted for Ed Yong's awesome Not Exactly Rocket Science, but if I'd had a second vote I'd also have voted for Eric Johnson's blog The Primate Diaries.

Friday, March 05, 2010

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, but its worth noting them again with their full journal reference information.

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."

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"


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.

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!

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."