The Quasar Absorption Line Group at New Mexico State University Studying the extended chemically enriched gaseous regions surrounding early epoch galaxies. Welcome to our research group page. We are a small group of the Department of Astronomy at New Mexico State University engaged in several research projects that use the technique of quasar absorption lines to study the kinematic, ionization, and chemical conditions of gas associated with intermediate and high redshift galaxies. Our most recent research direction is to employ the technique of quasar absorption lines to Nbody + hydrodynamic simulations of galaxy evolution. Our goals are to contribute to the growing body of knowledge of the role of gas in galaxy formation and evolution. We also aim to contribute to the field of astrobiology by searching for the rise of organic matter in the interstellar medium of early-epoch galaxies.

Faculty
	Chris Churchill	Anatoly Klypin

Graduate Students
	Daniel Ceverino	Jessica Evans	Glenn Kacprzak	Brandon Lawton	Allison Widhalm
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Simulations of a z=1.3 Galaxy Using the Adaptive Refinenment Tree (ART) method in an N-body + hydrodynamic code allows very high resolution of particle mass and gas physics in regions where the dynamic and collapse timescales are short, while also allowing us to follow the formed galaxies in the cosmological setting. The gas cells are resolved at roughly 20pc (comoving). We simulate the formation and evolution of galaxies in the greater cosmic web and incorporate star formation and feedback physics, including real-time metal enrichment of the gas and radiative heating and colling in this metal enriched gas. Kinetics from the supernovae chemically enrich and deposit heat into the gas in the galaxies; the gas then outflows via kinetic impulse and natural advection. These simulations naturally yield metal enriched extended gaseous halos around the galaxies (as is observed in the universe using the technique of quasar absorption lines). The physical state (gas density, temperature, velocity, and metallicity) associated with a galaxy at z=1.3 is illustrated in N-body + hydrodynamic simulations. Each image is 1 Mpc across (co-moving). The galaxy stars, which are confined to the inner central 20 kpc region, are not shown in these images, only the gas. - (upper left) Hydrogen density distribution (red is 0.1, yellow is 0.001). - (upper right) Temperature distribution (white should emit soft X-rays, green is photoionized). - (lower left) velocity field (red upward and blue downward is 300 km/s OUTFLOW!). - (lower right) metallicity distribution (red is 0.5 solar, yellow is 0.05 solar). What you are seeing: In the density slice (upper left panel), the false color yellow gas has a density of n ~ 0.001 atoms per cubic centimeter. The long extended structures to the upper right and lower left are infalling filaments from the cosmic web. Red colored gas has n ~ 0.1 atoms per cubic centimeter. In the temperature slice (upper right panel), this gas corresponds to T ~ 30,000 Kelvin. Note the halo out to 500 kpc that is T ~ few x 10^5 K. In the center of these images is the galaxy, which is surrounded by turbulent, shock heated and adiabatically cooling gas. The lower right panel shows the metallicity of this halo gas (the filaments are chemically poor). These metals are distributed along a direction perpendicular to the infalling filaments. The lower left panel shows the gas kinematics in the plane of the sky. The X direction is positive upward, so the red colored gas is outflowing upward from the galaxy at ~300 km/s, whereas the blue colored gas is outflowing downward from the galaxy at ~300 km/s. The key to these simulations is that stellar feedback is required to heat the gas, which then outflows (> 300 km/s) in a perpendicular direction to the inflowing cool filaments. Natural advection propels the metals to distances of 500 kpc. We run "mock" quasar lines of sight through these halos, generate synthetic quasar spectra, study the absorption lines from the MgII 2796,2803, CIV 1548,1550, and OVI 1031,1037 transitions, and compare them to observed spectra of these transitions. We use the observations and mock spectra to place constraints on the physics of stellar feedback. There are no ad-hoc processes- everything seen here is the results of natural phsyical processes in the simulations. (Right click on images and drag on "View Image" to see enlarged views.)

Galaxy and Halo Kinematics In view of the above simulations, one of the observational constraints that can be placed on the physics implemented in the simulations is the relative kinematics of the galaxy and the chemically enriched halo gas. To do this, we locate quasars that have foreground galaxies with small angular projections in which the line of sight to the quasar pierces the extended gaseous halos of the galaxies. We then obtain high resolution spectra of the background quasar (to obtain absorption line diagnostics of the halo gas) and moderate resolution spectra of the foreground galaxies (to obtain their rotation curves). Below is an example of two galaxies associated with the same metal-line absorption system detected in high resolution spectrum of the quasar (obtained with the UVES spectrograph on the VLT). The rotation curves were obtained with the ESI spectrograph on the Keck II Telescope. - (center panel) HST/WFPC2 F702W image of the quasar field, including the two foreground galaxies, G1 and G2. The quasar (unmarked) is the brightest object in the right-center location of the image (note the dffraction spikes). Though you cannot "see" the chemically enriched gas extended around these galaxies, these galaxies do have extended halos similar to those shown in the simulations above (the gas is observed in absorption in the quasar spectrum). The ESI slit positions are superimposed over the galaxies; the relative spatial position (in arcseconds) along the slit are indicated with "+" and "-," with "+" referring to positive spatial positions. Note that these directions are marked on the y-axes of the upper left and right panels illustrating the galaxy rotation curves. - (left panels) The top panel is the projected rotation curve (kinematics) of galaxy G1 given in rest-frame velocity relative to the galaxy systemtic redshift; the center panel is the absorption from the MgII 2796 transition (observed in the quasar spectum) and the lower panel is that of the MgII 2803 transition. The velocity scale of the absorbing gas is also relative to the galaxy systemtic redshift. - (right panels) Same as left panels but for galaxy G2. Note that the both of the galaxies' rotational velocities overlap completely with the observed MgII absorption kinematics. Halo models show that absorbing gas kinematics are consistent with extended an gaseous halo exhibiting disk-like rotation. Tidal tails of both G1 and G2 seen in the HST image suggest possible galaxy-galaxy harassment/interaction. Thus, it is likely that both of these galaxies are host to the absorption. Look out for two upcoming papers; one on the analysis two double galaxy systems (Kacprzak et al. 2007d, in prep) and the other is a comparison study of gaseous halo and galaxy kinematics (Kacprzak et al. 2007e, in prep). The second paper will show that the halo gas does NOT exhibit extend disk-like rotation as previously shown.

Faculty Chris Churchill [ Home Page | Dept Profile ] Assistant Professor Ph.D. Astronomy & Astrophysics, UCSC, 1997 Chris' main research interests have focused on the statistical properties of MgII absorbers and their associated galaxies. One of the most interesting questions is how gas is distributed around galaxies and what the velocity spread (kinematics) of the gas is and its relationship to the shape and size (morphology) of the galaxy. More recently, Chris has been spearheading the effort to generate mock quasar spectra through simulated galaxy halos cosmolocigal simulations. Chris spends much of his time mentoring students. He is also in the process of writing a text book called Fundamentals of Quasar Absorption Spectroscopy (some chapters available). Chris' Selected Papers Lawton, B., Churchill, C. W., York, B. A., Ellison, S. L., Snow, T. P., Johnson, R. A., Ryan, S. G., & Benn, C. R. 2008, AJ, submitted Diffuse Interstellar Bands in Seven Intermediate Redshift Damped Ly-alpha Absorbers (arXiv:0801.0447) Kacprzak, G. G., Churchill, C. W., Steidel, C. C., Murphy, M. T. 2008, AJ, in press Halo Gas Cross Sections And Covering Fractions of MgII Absorption Selected Galaxies (arXiv:0710.5765) Churchill, C. W., Kacprzak, G. G., Steidel, C. C., & Evans, J. L. 2007, ApJ, 661, 714 On the Heterogeneity of Metal--Line and Ly-alpha Absorption in Galaxy Halos at z=0.7 Kacprzak, G. G., Churchill, C. W., Steidel, C. C., Murphy, M. T., Sargent, W. L. W., & Rauch, M. 2007, ApJL, 662, 909 A Correlation Between Galaxy Morphology and MgII Halo Absorption Strength Chris' Selected Presentations (PDF best viewed in Acrobat) Using QSO Absorption Lines to Constrain Galaxy Formation (Munich, Germany 09/07) Observational Properties of the IGM/Galaxy Interface (Socorro, NM 10/06) MgII Absorption Through Galaxies at Intermediate Redshifts (Shanghai, China 03/05)

Anatoly Klypin [ Home Page | Dept Profile ] Professor Ph.D. Physics, Institute of Applied Mathematics, Moscow 1980 Anatoly's research interests include testing cosmological models using different techniques. He is actively involved in developing new numerical methods for cosmological simulations and using supercomputers to make accurate theoretical predictions. He has published over 90 papers in refereed journals. Anatoly's main interests also include the large-scale structure of the galactic distribution, the formation and structure of galaxies and galaxy clusters, galactic models, and dark matter in galaxies.

Graduate Students Daniel Ceverino [ Home Page | Dept Profile ] Graduate Student B.S. University of Seville 2002 Daniel is currently working on problems of cosmological interest. He uses N-body + hydrodynamic simulations to study the dynamics of disk galaxies and the affects of stellar feedback on the extended gaseous halos of the formed galaxies. Many of the key physical processes are still not well understood and their effects on galactic scales are not clear. These effects include the formation of stars inside gaseous clouds and feedback processes such as supernova explosions. The code in which these key processes are addressed includes radiative cooling and heating of a plasma with a given metallicity, star formation and stellar feedback which includes thermal feedback and metal enrichment. Daniel is working toward finding a more realistic treatment of these processes. Daniel's Selected Papers Ceverino, D., & Klypin, A. A. 2008, ApJ, submitted The Role of Stellar Feedback in the Formation of Galaxies (arXiv:0712.3285) Ceverino, D., & Klypin, A. A. 2007, NMRAS, 379, 1155 Resonances in Barred Galaxies

Jessica Evans [ Home Page | Dept Profile ] Graduate Student B.S. College of New Jersey 2002 Jessica is interested in a wide range of research topics, ranging from galaxy structure and dynamics, and large scale structure, to astronomical instrumentation. Her current project is based on a survey of 100+ weak MgII absorbers (those with equivalent widths, W(2796), less than 0.3 Å) found within 132 HIRES and 200+ UVES quasar spectra. The spectra are 97% complete to W(2796) = 0.02 Å over the redshift range 0.15-1.45. She has discovered pronounced evidence for evolution in the redshift path density, dN/dz, which decreases monotonically toward higher redshift. Jessica is supported by an NMSU Space & Areospace Cluster Fellowship and a NASA New Mexico Space Grant Fellowship. Jessica's Selected Papers Churchill, C. W., Kacprzak, G. G., Steidel, C. C., & Evans, J. L. 2007, ApJ, 661, 714 On the Heterogeneity of Metal--Line and Ly-alpha Absorption in Galaxy Halos at z=0.7

Glenn Kacprzak [ Home Page | Dept Profile ] Graduate Student M.S. Astronomy, Saint Mary's University, 2005 B.S. Astrophysics, Queen's University, 2001 Glenn is studying the detailed kinematics of MgII absorption from galaxies and the relationship to the morphologies, orientations, kinematics, and stellar populations of the host galaxies. He uses images of the galaxies taken with the Hubble Space Telescope and HIRES/Keck spectra of the the quasars. He obtains quantified morphological parameters of the galaxies using the program GIM2D. Using these techniques, Glenn reported a significant (3.2 sigma) correlation between the asymmetric perturbations in the galaxy morphologies and the strength of the MgII absorption. The implication is that processes that increase the halo gas population also modify the galaxy morphology- events such as minor mergings or IGM accretion events. Glenn is currently studying the realtion between galaxy kinematics and MgII halo gas kinematics. He obtained ESI/Keck spectra of 10 MgII absorbing galaxies and has extracted their rotation curves from several various emission lines. In two quasar fields, multiple galaxies are asscoaited with the absorption. He will be publishing a paper on this work in the Spring of 2008. For further details on Glenn's work and a complete bibliography, visit Glenn's Home Page Glenn's Selected Papers Kacprzak, G. G., Churchill, C. W., Steidel, C. C., Murphy, M. T. 2008, AJ, in press Halo Gas Cross Sections And Covering Fractions of MgII Absorption Selected Galaxies (arXiv:0710.5765) Churchill, C. W., Kacprzak, G. G., Steidel, C. C., & Evans, J. L. 2007, ApJ, 661, 714 On the Heterogeneity of Metal--Line and Ly-alpha Absorption in Galaxy Halos at z=0.7 Kacprzak, G. G., Churchill, C. W., Steidel, C. C., Murphy, M. T., Sargent, W. L. W., & Rauch, M. 2007, ApJL, 662, 909 A Correlation Between Galaxy Morphology and MgII Halo Absorption Strength Masiero, J.R., Charlton, J.C., Ding, J., Churchill, C.W., & Kacprzak, G.G. 2005, ApJ, 623, 57 Models of Five Absorption Line Systems Along the Line of Sight Toward PG 0117+213

Brandon Lawton [ Home Page | Dept Profile ] Graduate Student B.S. Astronomy, University of Washington, 2002 Brandon is searching for Diffuse Interstellar Bands (DIBs) in high redshift galaxies. DIB absorption, seen throughout interstellar medium of the Milky Galaxy, is highly believed to originate from complex organic molecules in interstellar gas clouds. The strength of DIB absorption is propotional (at a high significance level) to the neutral hydrogen column density, N(HI), of the gas. Using the Apache Point Observatory 3.5 meter, and the Keck, Subaru, VLT, and WHT telescopes, he is probing very high N(HI) Damped Ly-alpha absorbers, or DLAs, using the technique of quasar absorption lines (looking for DIBs in quasar spectra). Brandon has recently published a paper on the results for 7 DLAs, where he has been able to place upper limits on their reddening, E(B-V), and lower limits on ther gas-to-dust ratios using the DIBs. His ultimate goal is to chart the cosmic evolution of organic molecules in galaxies Brandon will soon be studying a large suite of Keck/ESI spectra of ultra-luminous infrared galaxies (ULIRGs) in collaboration with David Rupke (UMD), Sylvian Velliuex (UMD), and Crystal Martin (UMD). DIBs have been detected in 7 of the galaxies in the sample for this work in progress. Brandon is supported by a NASA Graduate Student Research Program (GSRP) Fellowship and a NASA New Mexico Space Grant Fellowship. Brandon's Selected Papers Lawton, B., Churchill, C. W., York, B. A., Ellison, S. L., Snow, T. P., Johnson, R. A., Ryan, S. G., & Benn, C. R. 2008, AJ, submitted Diffuse Interstellar Bands in Seven Intermediate Redshift Damped Ly-alpha Absorbers (arXiv:0801.0447) York, B. A., Ellison, S. E., Lawton, B., Churchill, C. W., Snow, T. P., Johnson, R. A., & Ryan, S. G. 2006, ApJ, 647, L29 Detection of the 5780 Diffuse Interstellar Band in a z=0.5 Damped Lyman-alpha System

Allison Widhalm [ Home Page | Dept Profile ] Graduate Student B.S. University of Southern California 2005 Allison has recently defined her PhD dissertation research (and has made some progress to date). She is probing Milky Way-like galaxy halos for CIV, NV, OVI absorption in the N-body + hydrodynamic simulations. She is interested in understanding the detailed role of stellar feedback and gas dynamics in the evolution of our very own Milky Way galaxy. The Milky Way is excellent for this study because there is a plethora of detailed data on the Halo. Allison will generate synthetic quasar absorption line spectra with the same pixelizations, resolutions, signal-to-noise characteristics as observed quasar spectra from the HST Quasar Absorption Line Key Project and FUSE observations. Using her synthetic spectra, Allison will reproduce the published analyses of these surveys, including the sky covering fractions, scale heights, inferred relative abundance ratios, and line of sight velocities of the optical depths. The idea is that disparities between the simulation data and the observational data provide powerful constraints on Galactic gas feedback recipes in the simulations.

Past Graduate Students Sarah Giandoni [ Home Page | Dept Profile ] Graduated 2005 (advisor: Chris Churchill) M.S. Astronomy, NMSU, 2005 B.S. Physics, Wyoming, 2003 Sarah did an excellent thesis on the absorbing gas properties in the spectrum of the quasar PKS 0312-330. See her research description. Sarah now does top secret work for the U.S. Government at White Sands Missle Range (very hush hush...). Dr. Don Lubowich [ Home Page | Dept Profile ] Graduated 2006 (advisor: Chris Churchill) Ph.D. Astronomy, NMSU, 2006 M.S. Physics, NMSU, 1977 Congratulations to Don for successfully defending his Ph.D. thesis on June 22, 2006. Studying the abundance of deuterium in the Galaxy. One goal is to use primordial deuterium abundance to establish a method of dating objects as a function of location in the disk of the Milky Way. This can be complicated by the infalling of high velocity clouds that have primitive abundances of deuterium. BBC Press Release Stars on Sundays

Outside Collaborators - Nicolas Bouche' (MPE) - Jane Charlton (PSU) - Andy Connolly (Pitt) - Sara Ellison (Victoria) - Sebastian Lopez (U Chile) - Naoto Kobayashi (Tokyo) - Michael Murphy (Cambridge) - Michael Rauch (Carnegie) - Wal Sargent (Caltech) - Ted Snow (Boulder) - Chuck Steidel (Caltech) - Don York (Chicago) Other Groups/People - California Institute of Technology - Institut d' Astrophysique de Paris - Northwestern University - Pennsylvania State University - University of Arizona - University of Florida - University of Hawaii - University of Pittsburgh - University of Wyoming - DIB People Research Related Links Tutorials - What is a Quasar/QSO? - More Details on Quasars - Astronomical Spectroscopy - Gene Smith's QSO/AGN Tutorial - Bill Keel's QSO/AGN Gallery - Ed Wright's Lyman-&alpha Forest - Joanne Cohn's Lyman-&alpha Absorbers - Kason Prochaska's Damped Lyman-&alpha Absorbers - Chris Churchill's MgII Absorbers - PBS Origins of Life - Nick Cox's Diffuse Interstellar Bands - Tom Lehrer's "The Elements" (humor) Research Papers - Our Recent Publications - NASA/ADS QALs - John Bahcall Papers Quasar Data - Churchill HIRES - UVES Squad (password required) - Bechtold FOS

Science Links Resources/Surveys - Astronomy Resources - NED - UVES Large Program - Standard Stars - Bright Supernovae - Supernova Links - 2dF Galaxy Survey - 6dF Galaxy Survey - CfA Galaxy Survey (zcat) - SDSS DR4 SkyServer Astrobiology - NASA Astrobiology Institute - Astrobiology Netherlands - Astro Chemistry Organization Modeling/Analysis Resources - Cloudy & Associates - Starburst 99 - GALAXEV - Gaia - SExtractor - Gim2d Facilities - DIS/APO - SPIcam/APO - NIC-FIPS/APO - SPIcam Exp Calc - NOAO - HDS/Subaru - IRCS/Subaru - HIRES/Keck - UVES/VLT - Hubble Space Telescope - COS/HST - FUSE Atomic/Molecular Database - NIST Atomic Data Center - NIST Atomic Spectra Database - NIST Atomic Data for Astrophysics - NIST Atomic Spectra Lines by Element - Grotrian Diagrams - NIST Atomic Spectra Textbook - DIB Line Catalog - Verner's Atomic Data

This page created and maintained by Chris Churchill; last update: December 2007