Friday, November 20, 2009

Interesting Astrophysics: Nov 16 to 20

Its a quiet week in terms of interesting papers and preprints. Given the small number of papers no added introduction to them is necessary.


Galaxies and Starbursts

On the interstellar medium and star formation demographics of galaxies in the local universe
Matthew S. Bothwell, Robert C. Kennicutt Jr, and Janice C. Lee, 2090, MNRAS, 400, 154
Full Text: HTML, PDF (Size: 1632K)

Photodissociation chemistry footprints in the Starburst galaxy NGC 253
Sergio Martin, J. Martin-Pintado, S. Viti, arXiv:0911.2673 [ps, pdf, other]
Comments: 32 pages, 4 figures, Published in ApJ
Journal-ref: 2009 ApJ 706 1323-1330

Origin(s) of the Highly Ionized High-Velocity Clouds Based on Their Distances
N. Lehner, J. C. Howk, arXiv:0911.2732 [ps, pdf, other]
Comments: Submitted to the ApJ Letters


Black Holes and AGN

Quasar Outflow Contribution to AGN Feedback: Observations of QSO SDSS J0838+2955
Maxwell Moe, Nahum Arav, Manuel A. Bautista, Kirk T. Korista, arXiv:0911.3332 [ps, pdf, other]
Comments: 28 pages, 7 figures, 4 tables, published in Astrophysical Journal
Journal-ref: 2009 ApJ 706 525-534

Their full abstract: "We present a detailed analysis of the Astrophysical Research Consortium 3.5 m telescope spectrum of QSO SDSS J0838+2955. The object shows three broad absorption line (BAL) systems at 22,000, 13,000, and 4900 km s^-1 blueshifted from the systemic redshift of z=2.043. Of particular interest is the lowest velocity system that displays absorption from low-ionization species such as Mg II, Al II, Si II, Si II*, Fe II and Fe II*. Accurate column densities were measured for all transitions in this lowest velocity BAL using an inhomogeneous absorber model. The ratio of column densities of Si II* and Fe II* with respect to their ground states gave an electron number density of log n_e (cm^-3) = 3.75 +/- 0.22 for the outflow. Photoionization modeling with careful regards to chemical abundances and the incident spectral energy distribution predicts an ionization parameter of log U_H = -1.93 +/- 0.21 and a hydrogen column density of log N_H (cm^-2) = 20.80 +/- 0.28. This places the outflow at 3.3+1.5-1.0 kpc from the central AGN. Assuming that the fraction of solid angle subtended by the outflow is 0.2, these values yield a kinetic luminosity of (4.5+3.1-1.8) x 10^45 erg s^-1, which is (1.4+1.1-0.6)% the bolometric luminosity of the QSO itself. Such large kinetic luminosity suggests that QSO outflows are a major contributor to AGN feedback mechanisms."



Numerical Astrophysics and Hydrodynamics

Turbulence modeling and the physics of the intra-cluster medium

L. Iapichino, A. Maier, W. Schmidt, J. C. Niemeyer, arXiv:0911.2629 [ps, pdf, other]
Comments: To appear in the proceedings of the "Invisible Universe International Conference"


Characterizing Magnetohydrodynamic Turbulence in the Small Magellanic Cloud
Blakesley Burkhart, Snezana Stanimirovic, Alex Lazarian, Grzegorz Kowal, arXiv:0911.3652 [ps, pdf, other]


Stars, Supernovae and Planets

A Feature Movie of SiO Emission 20-100 AU from the Massive Young Stellar Object Orion Source I
L. D. Matthews, L. J. Greenhill, C. Goddi, C. J. Chandler, E. M. L. Humphreys, M. Kunz, rXiv:0911.2473 [pdf, other]

Comments: Accepted to ApJ (January 2010); a full resolution version along with two accompanying GIF movies may be found at this http URL

An Unusually Fast-Evolving Supernova
Dovi Poznanski, Ryan Chornock, Peter E. Nugent, Joshua S. Bloom, Mohan Ganeshalingam, Douglas C. Leonard, Weidong Li, Rollin C. Thomas, arXiv:0911.2699 [pdf, other]
Comments: Science in press, first published online on Nov 5, 2009 in Science Express. Includes supporting online materia

The low-mass Initial Mass Function in the 30 Doradus starburst cluster
M. Andersen, H. Zinnecker, A. Moneti, M. J. McCaughrean, B. Brandl, W. Brandner, G. Meylan, D. Hunter, arXiv:0911.2755 [ps, pdf, other]
Comments: Accepted in ApJ. Abstract abridged

How Common are Extrasolar, Late Heavy Bombardments?
Mark Booth, Mark C. Wyatt, Alessandro Morbidelli, Amaya Moro-MartĂ­n, Harold F. Levison, arXiv:0911.3271 [ps, pdf, other]
Comments: 2 pages, 1 figure. Contribution to the conference proceedings for 'Pathways towards habitable planets'


Other

A Vigorous Explorer Program
Martin Elvis, et al, arXiv:0911.3383 [pdf]
Comments: 18 pages, no figures. An Activities/Program White Paper submitted to the Astro2010 NAS/NRC Decadal Review of Astronomy and Astrophysics

Friday, November 13, 2009

Interesting Astrophysics: Nov 09 to 13

A mixed set of interesting preprints this week, with a strong emphasis on winds, either supernova-driven winds starbursts at high redshift (Kornei et al) or possibly from the center of our own galaxy (Law), and even outflows driven by black holes (King).

A second theme with a strong showing of interesting papers is astrobiology: the biological effects of radiation from "normal" stellar processes on the main sequence (Cuntz et al) or from Gamma ray bursts (Martin et al).


Galaxies and Starbursts

Morphologies of local Lyman break galaxy analogs II: A Comparison with galaxies at z=2-4 in ACS and WFC3 images of the Hubble Ultra Deep Field
R.A. Overzier, T.M. Heckman, D. Schiminovich, A. Basu-Zych, T. Goncalves, D.C. Martin, R.M. Rich, arXiv:0911.1279 [ps, pdf, other]
Comments: Submitted to ApJ (14 pages, 7 figures). For a high-resolution colour version and background material, see this http URL

The Relationship Between Stellar Populations and Lyman Alpha Emission in Lyman Break Galaxies
Katherine A. Kornei, Alice E. Shapley, Dawn K. Erb, Charles C. Steidel, Naveen A. Reddy, Max Pettini, Milan Bogosavljevic, arXiv:0911.2000 [ps, pdf, other]
Comments: 24 pages, 15 figures, submitted to ApJ

From their abstract: "We accordingly conclude that, within the LBG sample, objects with strong Lya emission represent a later stage of galaxy evolution in which supernovae-induced outflows have reduced the dust covering fraction. We also examined the hypothesis that the attenuation of Lya photons is lower than that of the continuum, as proposed by some, but found no evidence to support this picture."

A Multiwavelength View of a Mass Outflow from the Galactic Center
C. J. Law, arXiv:0911.2061 [pdf, other]
Comments: Accepted to ApJ. 15 pages, 8 (compressed) figures

From the abstract: "I compare the physical conditions of the GC lobe to several models and find best agreement with the canonical starburst outflow model. The formation of the GC lobe is consistent with the currently observed pressure and star formation rate in the central tens of parsecs of our Galaxy. Outflows of this scale are more typical of dwarf galaxies and would not be easily detected in nearby spiral galaxies. Thus, the existence of such an outflow in our own Galaxy may indicate that it is relatively common phenomenon in the nuclei of spiral galaxies."


Black Holes and AGN

Discovery of a 115 Day Orbital Period in the Ultraluminous X-ray Source NGC 5408 X-1
Tod E. Strohmayer, arXiv:0911.1339 [ps, pdf, other]
Comments: Accepted for Publication in the Astrophysical Journal Letters

Black Hole Outflows
A.R. King, arXiv:0911.1639 [ps, pdf, other]
Comments: MNRAS, to appear


Numerical Astrophyics

Generating on-the-fly large samples of theoretical spectra through N-dimensional grid
Ching-Wa Yip, arXiv:0911.1280 [ps, pdf, other]
Comments: 7 pages, 5 figures, 1 table. Accepted for publication in AJ


Stars, Supernovae and Planets

Biological Damage due to Photospheric, Chromospheric and Flare Radiation in the Environments of Main-Sequence Stars
M. Cuntz, E. F. Guinan, R. L. Kurucz, arXiv:0911.1982 [ps, pdf, other]
Comments: 8 pages, 4 figues, Planetary Systems as Potential Sites for Life, Invited Paper, IAU Symposium 264, eds. A. Kosovichev et al. (San Francisco: Astr. Soc. Pac.), in press

Effects of Gamma Ray Bursts in Earth Biosphere
Osmel Martin, Rolando Cardenas, Mayrene Guimaraes, Liuba Penate, Jorge Horvath, Douglas Galante, arXiv:0911.2196 [pdf, other]
Comments: Accepted for publication in Astrophysics & Space Science

Friday, November 06, 2009

Interesting Astrophysics: Nov 02 to Nov 06

Of particular note this week are Crighton et al (who suggest a particular case of intergalactic metal line absorption can be associated with a z=0.2272 galaxy polluting a region ~200 kpc in radius), Bertone et al (metal line cooling from the IGM predicted in the OWLS simulations) Risaliti & Elvis (a line driven model for AGN winds), and Bond et al (terrestrial planet formation models that correctly predict the observed elemental abundances also predict that terrestrial planets form wet and do not need significant water delivery from comets).


Galaxies and Starbursts

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, I. Smail, R. McDermid, N. Nesvadba, arXiv:0911.0014 [ps, pdf, other]
Comments: 10 pages, 5 figures, 1 table. Resubmitted to MNRAS after taking account of referees feedback

Galaxies at Redshift ~0.5 Around Three Closely Spaced Quasar Sightlines
Neil H. M. Crighton, Simon L. Morris, Jill Bechtold, Robert A. Crain, Buell T. Jannuzi, Allen Shone, Tom Theuns, arXiv:0911.0368 [pdf, other]
Comments: 45 pages, 21 figures. Accepted by MNRAS

From their abstract: "We identify a galaxy at z=0.2272 with associated metal absorption in two sightlines, each 200 kpc away. By constraining the star formation history of the galaxy, we show the gas causing this metal absorption may have been enriched and ejected by the galaxy during a burst of star formation 2 Gyr ago."

Enhanced Dense Gas Fraction in Ultra-Luminous Infrared Galaxies
S. Juneau, D. T. Narayanan, J. Moustakas, Y. L. Shirley, R. S. Bussmann, R. C. Kennicutt Jr, P. A. Vanden Bout, arXiv:0911.0413 [ps, pdf, other]
Comments: 20 pages, 10 figures. To be published in The Astrophysical Journal (accepted)


Black Holes and AGN

Comparison between the Luminosity functions of X-ray and [OIII] selected AGN
I. Georgantopoulos, A. Akylas, arXiv:0911.0102 [ps, pdf, other]
Comments: 7 pages to appear in Astronomy & Astrophysics

A non-hydrodynamical model for acceleration of line-driven winds in Active Galactic Nuclei
G. Risaliti, M. Elvis, arXiv:0911.0958 [ps, pdf, other]
Comments: 15 pages, 9 figures. Accepted for publication in Astronomy & Astrophysics


Numerical Astrophysics

Metal-line emission from the warm-hot intergalactic medium: I. Soft X-rays
Serena Bertone, Joop Schaye, Claudio Dalla Vecchia, C.M. Booth, Tom Theuns, Robert P.C. Wiersma, arXiv:0910.5723 [ps, pdf, other]

The Enrichment of Intergalactic Medium With Adiabatic Feedback I: Metal Cooling and Metal Diffusion
Sijing Shen, James Wadsley, Gregory Stinson, arXiv:0910.5956 [ps, pdf, other]
Comments: 16 pages, 11 figures, submitted to MNRAS

Ram-pressure stripping of halo gas in disc galaxies: implications for galactic star formation in different environments
Kenji Bekki, 2009, MNRAS, 399, 2221
Full Text: HTML, PDF (Size: 4409K)

The impact of feedback on the low redshift Intergalactic Medium
Luca Tornatore, Stefano Borgani, Matteo Viel, Volker Springel, arXiv:0911.0699 [ps, pdf, other]
Comments: revised version after referee's comments


Stars, Supernovae and Planets

Making the Earth: Combining Dynamics and Chemistry in the Solar System
Jade C. Bond, Dante S. Lauretta, David P. O'Brien, arXiv:0911.0426 [ps, pdf, other]
Comments: 61 pages (including online material), 12 figures (7 in paper, 5 online). Accepted to Icarus

From their abstract: "Bulk elemental abundances based on disk equilibrium studies have been determined for the simulated terrestrial planets of O'Brien et al. (2006). These abundances are in excellent agreement with observed planetary values, indicating that the models of O'Brien et al. (2006) are successfully producing planets comparable to those of the Solar System in terms of both their dynamical and chemical properties. Significant amounts of water are accreted in the present simulations, implying that the terrestrial planets form "wet" and do not need significant water delivery from other sources. Under the assumption of equilibrium controlled chemistry, the biogenic species N and C still need to be delivered to the Earth as they are not accreted in significant proportions during the formation process."