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1. Beyond Spectroscopy. II. Stellar Parameters for over 20 Million Stars in the Northern Sky from SAGES DR1 and Gaia DR3

Author

Huang, Yang, primary, Beers, Timothy C., additional, Yuan, Haibo, additional, Tan, Ke-Feng, additional, Wang, Wei, additional, Zheng, Jie, additional, Li, Chun, additional, Lee, Young Sun, additional, Li, Hai-Ning, additional, Zhao, Jing-Kun, additional, Xue, Xiang-Xiang, additional, Liu, Yujuan, additional, Zhang, Huawei, additional, Sun, Xue-Ang, additional, Li, Ji, additional, Gu, Hong-Rui, additional, Wolf, Christian, additional, Onken, Christopher A., additional, Liu, Jifeng, additional, Fan, Zhou, additional, and Zhao, Gang, additional

Published
2023
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3. Erratum “Milky Way Tomography with the SkyMapper Southern Survey. II. Photometric Recalibration of SMSS DR2” (2021, ApJ, 907, 68)

Author

Huang, Yang, primary, Yuan, Haibo, additional, Li, Chengyuan, additional, Wolf, Christian, additional, Onken, Christopher A., additional, Beers, Timothy C., additional, Casagrande, Luca, additional, Mackey, Dougal, additional, Da Costa, Gary S., additional, Bland-Hawthorn, Joss, additional, Stello, Dennis, additional, Nordlander, Thomas, additional, Ting, Yuan-Sen, additional, Buder, Sven, additional, Sharma, Sanjib, additional, and Liu, Xiaowei, additional

Published
2022
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4. Milky Way Tomography with the SkyMapper Southern Survey. II. Photometric Recalibration of SMSS DR2

Author

Huang, Yang, primary, Yuan, Haibo, additional, Li, Chengyuan, additional, Wolf, Christian, additional, Onken, Christopher A., additional, Beers, Timothy C., additional, Casagrande, Luca, additional, Mackey, Dougal, additional, Da Costa, Gary S., additional, Bland-Hawthorn, Joss, additional, Stello, Dennis, additional, Nordlander, Thomas, additional, Ting, Yuan-Sen, additional, Buder, Sven, additional, Sharma, Sanjib, additional, and Liu, Xiaowei, additional

Published
2021
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7. ANISOTROPY OF THIRD-ORDER STRUCTURE FUNCTIONS IN MHD TURBULENCE

Author

Andrea Verdini, Petr Hellinger, Wolf-Christian Müller, Simone Landi, Roland Grappin, Laboratoire de Physique des Plasmas (LPP), Université Paris-Sud - Paris 11 (UP11)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
Field (physics), FOS: Physical sciences, 01 natural sciences, Physics - Space Physics, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010306 general physics, Anisotropy, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Physics, Turbulence, Isotropy, Astronomy and Astrophysics, Fluid mechanics, Space Physics (physics.space-ph), Physics - Plasma Physics, Computational physics, Plasma Physics (physics.plasm-ph), Solar wind, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Cascade, Physics::Space Physics, Magnetohydrodynamics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

The measure of the third-order structure function, Y, is employed in the solar wind to compute the cascade rate of turbulence. In the absence of a mean field B0=0, Y is expected to be isotropic (radial) and independent of the direction of increments, so its measure yields directly the cascade rate. For turbulence with mean field, as in the solar wind, Y is expected to become more two dimensional (2D), that is, to have larger perpendicular components, loosing the above simple symmetry. To get the cascade rate one should compute the flux of Y, which is not feasible with single-spacecraft data, thus measurements rely upon assumptions about the unknown symmetry. We use direct numerical simulations (DNS) of magneto-hydrodynamic (MHD) turbulence to characterize the anisotropy of Y. We find that for strong guide field B0=5 the degree of two-dimensionalization depends on the relative importance of shear and pseudo polarizations (the two components of an Alfv\'en mode in incompressible MHD). The anisotropy also shows up in the inertial range. The more Y is 2D, the more the inertial range extent differs along parallel and perpendicular directions. We finally test the two methods employed in observations and find that the so-obtained cascade rate may depend on the angle between B0 and the direction of increments. Both methods yield a vanishing cascade rate along the parallel direction, contrary to observations, suggesting a weaker anisotropy of solar wind turbulence compared to our DNS. This could be due to a weaker mean field and/or to solar wind expansion., Comment: Some text editing and typos corrected, 13 pages, 6 figures, to be published in ApJ

Published
2015

10. LARGE-SCALE MAGNETIC STRUCTURE FORMATION IN THREE-DIMENSIONAL MAGNETOHYDRODYNAMIC TURBULENCE

Author

Shiva Kumar Malapaka and Wolf-Christian Müller

Subjects
Physics, Forcing (recursion theory), Structure formation, Radio relics, Magnetic structure, Space and Planetary Science, Magnetic helicity, Turbulence, Astronomy and Astrophysics, Magnetic reconnection, Astrophysics, Galaxy cluster, Computational physics
Abstract

The inverse cascade of magnetic helicity in 3D-MHD turbulence is believed to be one of the processes responsible for large scale magnetic structure formation in astrophysical systems. In this work we present an exhaustive set of high resolution direct numerical simulations (DNS) of both forced and decaying 3D-MHD turbulence, to understand this structure formation process. It is rst shown that an inverse cascade of magnetic helicity in small-scale driven turbulence does not necessarily generate coherent large-scale magnetic structures. The observed large-scale magnetic eld, in this case, is severely perturbed by magnetic uctuations generated by the small-scale forcing. In the decaying case, coherent large-scale structure form similar to those observed astronomically. Based on the numerical results the formation of large-scale magnetic structures in some astrophysical systems, is suggested to be the consequence of an initial forcing which imparts the necessary turbulent energy into the system, which, after the forcing shuts o, decays to form the large-scale structures. This idea is supported by representative examples e.g. cluster of galaxies. Subject headings: large-scale magnetic structures: general | magnetic helicity inverse cascade: individual(Radio relics), magnetic reconnection

Published
2013

11. MODELING STATISTICAL PROPERTIES OF SOLAR ACTIVE REGIONS THROUGH DIRECT NUMERICAL SIMULATIONS OF 3D-MHD TURBULENCE

Author

Wolf-Christian Müller and Shiva Kumar Malapaka

Subjects
Physics, Photosphere, Solar flare, Turbulence, Flatness (systems theory), Phase (waves), Astronomy and Astrophysics, Astrophysics, Computational physics, law.invention, Physics::Fluid Dynamics, Space and Planetary Science, law, Intermittency, Physics::Space Physics, Astrophysics::Solar and Stellar Astrophysics, Magnetohydrodynamics, Flare
Abstract

Statistical properties of the Sun's photospheric turbulent magnetic field, especially those of the active regions (ARs), have been studied using the line-of-sight data from magnetograms taken by the Solar and Heliospheric Observatory and several other instruments. This includes structure functions and their exponents, flatness curves, and correlation functions. In these works, the dependence of structure function exponents ({zeta}{sub p}) of the order of the structure functions (p) was modeled using a non-intermittent K41 model. It is now well known that the ARs are highly turbulent and are associated with strong intermittent events. In this paper, we compare some of the observations from Abramenko et al. with the log-Poisson model used for modeling intermittent MHD turbulent flows. Next, we analyze the structure function data obtained from the direct numerical simulations (DNS) of homogeneous, incompressible 3D-MHD turbulence in three cases: sustained by forcing, freely decaying, and a flow initially driven and later allowed to decay (case 3). The respective DNS replicate the properties seen in the plots of {zeta}{sub p} against p of ARs. We also reproduce the trends and changes observed in intermittency in flatness and correlation functions of ARs. It is suggested from this analysis that an AR in themore » onset phase of a flare can be treated as a forced 3D-MHD turbulent system in its simplest form and that the flaring stage is representative of decaying 3D-MHD turbulence. It is also inferred that significant changes in intermittency from the initial onset phase of a flare to its final peak flaring phase are related to the time taken by the system to reach the initial onset phase.« less

Published
2013

12. COMPARING NUMERICAL METHODS FOR ISOTHERMAL MAGNETIZED SUPERSONIC TURBULENCE

Author

Kritsuk, Alexei G., primary, Nordlund, Åke, additional, Collins, David, additional, Padoan, Paolo, additional, Norman, Michael L., additional, Abel, Tom, additional, Banerjee, Robi, additional, Federrath, Christoph, additional, Flock, Mario, additional, Lee, Dongwook, additional, Shing Li, Pak, additional, Müller, Wolf-Christian, additional, Teyssier, Romain, additional, Ustyugov, Sergey D., additional, Vogel, Christian, additional, and Xu, Hao, additional

Published
2011
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14. THE MERGER-DRIVEN EVOLUTION OF MASSIVE GALAXIES

Author

Robaina, Aday R., primary, Bell, Eric F., additional, van der Wel, Arjen, additional, Somerville, Rachel S., additional, Skelton, Rosalind E., additional, McIntosh, Daniel H., additional, Meisenheimer, Klaus, additional, and Wolf, Christian, additional

Published
2010
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15. INTERACTING GALAXIES IN THE A901/902 SUPERCLUSTER WITH STAGES

Author

Heiderman, Amanda, primary, Jogee, Shardha, additional, Marinova, Irina, additional, van Kampen, Eelco, additional, Barden, Marco, additional, Peng, Chien Y., additional, Heymans, Catherine, additional, Gray, Meghan E., additional, Bell, Eric F., additional, Bacon, David, additional, Balogh, Michael, additional, Barazza, Fabio D., additional, Böhm, Asmus, additional, Caldwell, John A. R., additional, Häußler, Boris, additional, Jahnke, Knud, additional, Lane, Kyle, additional, McIntosh, Daniel H., additional, Meisenheimer, Klaus, additional, Sánchez, Sebastian F., additional, Somerville, Rachel S., additional, Taylor, Andy, additional, Wisotzki, Lutz, additional, Wolf, Christian, additional, and Zheng, Xianzhong, additional

Published
2009
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16. LESS THAN 10 PERCENT OF STAR FORMATION INz∼ 0.6 MASSIVE GALAXIES IS TRIGGERED BY MAJOR INTERACTIONS

Author

Robaina, Aday R., primary, Bell, Eric F., additional, Skelton, Rosalind E., additional, McIntosh, Daniel H., additional, Somerville, Rachel S., additional, Zheng, Xianzhong, additional, Rix, Hans-Walter, additional, Bacon, David, additional, Balogh, Michael, additional, Barazza, Fabio D., additional, Barden, Marco, additional, Böhm, Asmus, additional, Caldwell, John A. R., additional, Gallazzi, Anna, additional, Gray, Meghan E., additional, Häussler, Boris, additional, Heymans, Catherine, additional, Jahnke, Knud, additional, Jogee, Shardha, additional, van Kampen, Eelco, additional, Lane, Kyle, additional, Meisenheimer, Klaus, additional, Papovich, Casey, additional, Peng, Chien Y., additional, Sánchez, Sebastián F., additional, Skibba, Ramin, additional, Taylor, Andy, additional, Wisotzki, Lutz, additional, and Wolf, Christian, additional

Published
2009
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17. BARRED GALAXIES IN THE ABELL 901/2 SUPERCLUSTER WITH STAGES

Author

Marinova, Irina, primary, Jogee, Shardha, additional, Heiderman, Amanda, additional, Barazza, Fabio D., additional, Gray, Meghan E., additional, Barden, Marco, additional, Wolf, Christian, additional, Peng, Chien Y., additional, Bacon, David, additional, Balogh, Michael, additional, Bell, Eric F., additional, Böhm, Asmus, additional, Caldwell, John A. R., additional, Häußler, Boris, additional, Heymans, Catherine, additional, Jahnke, Knud, additional, van Kampen, Eelco, additional, Lane, Kyle, additional, McIntosh, Daniel H., additional, Meisenheimer, Klaus, additional, Sánchez, Sebastian F., additional, Somerville, Rachel, additional, Taylor, Andy, additional, Wisotzki, Lutz, additional, and Zheng, Xianzhong, additional

Published
2009
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18. HISTORY OF GALAXY INTERACTIONS AND THEIR IMPACT ON STAR FORMATION OVER THE LAST 7 Gyr FROM GEMS

Author

Jogee, Shardha, primary, Miller, Sarah H., additional, Penner, Kyle, additional, Skelton, Rosalind E., additional, Conselice, Christopher J., additional, Somerville, Rachel S., additional, Bell, Eric F., additional, Zheng, Xian Zhong, additional, Rix, Hans-Walter, additional, Robaina, Aday R., additional, Barazza, Fabio D., additional, Barden, Marco, additional, Borch, Andrea, additional, Beckwith, Steven V. W., additional, Caldwell, John A. R., additional, Peng, Chien Y., additional, Heymans, Catherine, additional, McIntosh, Daniel H., additional, Häußler, Boris, additional, Jahnke, Knud, additional, Meisenheimer, Klaus, additional, Sanchez, Sebastian F., additional, Wisotzki, Lutz, additional, Wolf, Christian, additional, and Papovich, Casey, additional

Published
2009
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19. OBSCURED STAR FORMATION IN INTERMEDIATE-DENSITY ENVIRONMENTS: ASPITZERSTUDY OF THE ABELL 901/902 SUPERCLUSTER

Author

Gallazzi, Anna, primary, Bell, Eric F., additional, Wolf, Christian, additional, Gray, Meghan E., additional, Papovich, Casey, additional, Barden, Marco, additional, Peng, Chien Y., additional, Meisenheimer, Klaus, additional, Heymans, Catherine, additional, van Kampen, Eelco, additional, Gilmour, Rachel, additional, Balogh, Michael, additional, McIntosh, Daniel H., additional, Bacon, David, additional, Barazza, Fabio D., additional, Böhm, Asmus, additional, Caldwell, John A. R., additional, Häußler, Boris, additional, Jahnke, Knud, additional, Jogee, Shardha, additional, Lane, Kyle, additional, Robaina, Aday R., additional, Sanchez, Sebastian F., additional, Taylor, Andy, additional, Wisotzki, Lutz, additional, and Zheng, Xianzhong, additional

Published
2008
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20. An Explanation for the Observed Weak Size Evolution of Disk Galaxies

Author

Somerville, Rachel S., primary, Barden, Marco, additional, Rix, Hans‐Walter, additional, Bell, Eric F., additional, Beckwith, Steven V. W., additional, Borch, Andrea, additional, Caldwell, John A. R., additional, Hausler, Boris, additional, Heymans, Catherine, additional, Jahnke, Knud, additional, Jogee, Shardha, additional, McIntosh, Daniel H., additional, Meisenheimer, Klaus, additional, Peng, Chien Y., additional, Sanchez, Sebastian F., additional, Wisotzki, Lutz, additional, and Wolf, Christian, additional

Published
2008
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23. The Merger Rate of Massive Galaxies

Author

Bell, Eric F., primary, Phleps, Stefanie, additional, Somerville, Rachel S., additional, Wolf, Christian, additional, Borch, Andrea, additional, and Meisenheimer, Klaus, additional

Published
2006
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25. Dry Mergers in GEMS: The Dynamical Evolution of Massive Early‐Type Galaxies

Author

Bell, Eric F., primary, Naab, Thorsten, additional, McIntosh, Daniel H., additional, Somerville, Rachel S., additional, Caldwell, John A. R., additional, Barden, Marco, additional, Wolf, Christian, additional, Rix, Hans‐Walter, additional, Beckwith, Steven V., additional, Borch, Andrea, additional, Haussler, Boris, additional, Heymans, Catherine, additional, Jahnke, Knud, additional, Jogee, Shardha, additional, Koposov, Sergey, additional, Meisenheimer, Klaus, additional, Peng, Chien Y., additional, Sanchez, Sebastian F., additional, and Wisotzki, Lutz, additional

Published
2006
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26. GEMS: The Surface Brightness and Surface Mass Density Evolution of Disk Galaxies

Author

Barden, Marco, primary, Rix, Hans‐Walter, additional, Somerville, Rachel S., additional, Bell, Eric F., additional, Hausler, Boris, additional, Peng, Chien Y., additional, Borch, Andrea, additional, Beckwith, Steven V. W., additional, Caldwell, John A. R., additional, Heymans, Catherine, additional, Jahnke, Knud, additional, Jogee, Shardha, additional, McIntosh, Daniel H., additional, Meisenheimer, Klaus, additional, Sanchez, Sebastian F., additional, Wisotzki, Lutz, additional, and Wolf, Christian, additional

Published
2005
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27. The Evolution of Early‐Type Red Galaxies with the GEMS Survey: Luminosity‐Size and Stellar Mass–Size Relations Sincez = 1

Author

McIntosh, Daniel H., primary, Bell, Eric F., additional, Rix, Hans‐Walter, additional, Wolf, Christian, additional, Heymans, Catherine, additional, Peng, Chien Y., additional, Somerville, Rachel S., additional, Barden, Marco, additional, Beckwith, Steven V. W., additional, Borch, Andrea, additional, Caldwell, John A. R., additional, Hausler, Boris, additional, Jahnke, Knud, additional, Jogee, Shardha, additional, Meisenheimer, Klaus, additional, Sanchez, Sebastian F., additional, and Wisotzki, Lutz, additional

Published
2005
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28. Toward an Understanding of the Rapid Decline of the Cosmic Star Formation Rate

Author

Bell, Eric F., primary, Papovich, Casey, additional, Wolf, Christian, additional, Le Floc’h, Emeric, additional, Caldwell, John A. R., additional, Barden, Marco, additional, Egami, Eiichi, additional, McIntosh, Daniel H., additional, Meisenheimer, Klaus, additional, Perez‐Gonzalez, Pablo G., additional, Rieke, G. H., additional, Rieke, M. J., additional, Rigby, Jane R., additional, and Rix, Hans‐Walter, additional

Published
2005
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29. Bar Evolution over the Last 8 Billion Years: A Constant Fraction of Strong Bars in the GEMS Survey

Author

Jogee, Shardha, primary, Barazza, Fabio D., additional, Rix, Hans-Walter, additional, Shlosman, Isaac, additional, Barden, Marco, additional, Wolf, Christian, additional, Davies, James, additional, Heyer, Inge, additional, Beckwith, Steven V.W., additional, Bell, Eric F., additional, Borch, Andrea, additional, Caldwell, John A. R., additional, Conselice, Christopher J., additional, Dahlen, Tomas, additional, Häussler, Boris, additional, Heymans, Catherine, additional, Jahnke, Knud, additional, Knapen, Johan H., additional, Laine, Seppo, additional, Lubell, Gabriel M., additional, Mobasher, Bahram, additional, McIntosh, Daniel H., additional, Meisenheimer, Klaus, additional, Peng, Chien Y., additional, Ravindranath, Swara, additional, Sanchez, Sebastian F., additional, Somerville, Rachel S., additional, and Wisotzki, Lutz, additional

Published
2004
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31. GEMS Imaging of Red-Sequence Galaxies at [FORMULA][F]z~0.7[/F][/FORMULA]: Dusty or Old?

Author

Bell, Eric F., primary, McIntosh, Daniel H., additional, Barden, Marco, additional, Wolf, Christian, additional, Caldwell, John A. R., additional, Rix, Hans-Walter, additional, Beckwith, Steven V. W., additional, Borch, Andrea, additional, Hussler, Boris, additional, Jahnke, Knud, additional, Jogee, Shardha, additional, Meisenheimer, Klaus, additional, Peng, Chien, additional, Sanchez, Sebastian F., additional, Somerville, Rachel S., additional, and Wisotzki, Lutz, additional

Published
2003
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32. Detection of Massive Tidal Tails around the Globular Cluster Palomar 5 with Sloan Digital Sky Survey Commissioning Data

Author

Odenkirchen, Michael, primary, Grebel, Eva K., additional, Rockosi, Constance M., additional, Dehnen, Walter, additional, Ibata, Rodrigo, additional, Rix, Hans-Walter, additional, Stolte, Andrea, additional, Wolf, Christian, additional, Anderson, Jr., John E., additional, Bahcall, Neta A., additional, Brinkmann, Jon, additional, Csabai, István, additional, Hennessy, G., additional, Hindsley, Robert B., additional, Ivezić, Željko, additional, Lupton, Robert H., additional, Munn, Jeffrey A., additional, Pier, Jeffrey R., additional, Stoughton, Chris, additional, and York, Donald G., additional

Published
2001
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33. LESS THAN 10 PERCENT OF STAR FORMATION IN z 0.6 MASSIVE GALAXIES IS TRIGGERED BY MAJOR INTERACTIONS

Author

Robaina, Aday R., Bell, Eric F., Skelton, Rosalind E., McIntosh, Daniel H., Somerville, Rachel S., Zheng, Xianzhong, Rix, Walter, Bacon, David, Balogh, Michael, Barazza, Fabio D., Barden, Marco, Bohm, Asmus, R, John A., Gallazzi, Anna, Gray, Meghan E., Haussler, Boris, Heymans, Catherine, Jahnke, Knud, Jogee, Shardha, van, Eelco, Lane, Kyle, Meisenheimer, Klaus, Papovich, Casey, Peng, Chien Y., Sanchez, Sebastian F., Skibba, Ramin, Taylor, Andy, Wisotzki, Lutz, and Wolf, Christian

Abstract

Both observations and simulations show that major tidal interactions or mergers between gas-rich galaxies can lead to intense bursts of star formation. Yet, the average enhancement in star formation rate (SFR) in major mergers and the contribution of such events to the cosmic SFR are not well estimated. Here we use photometric redshifts, stellar masses, and UV SFRs from COMBO-17, 24 mm SFRs from Spitzer, and morphologies from two deep Hubble Space Telescope (HST) cosmological survey fields (ECDFS/GEMS and A901/STAGES) to study the enhancement in SFR as a function of projected galaxy separation. We apply two-point projected correlation function techniques, which we augment with morphologically selected very close pairs (separation <2'') and merger remnants from the HST imaging. Our analysis confirms that the most intensely star-forming systems are indeed interacting or merging. Yet, for massive (M * [?] 1010 M ) star-forming galaxies at 0.4 < z < 0.8, we find that the SFRs of galaxies undergoing a major interaction (mass ratios [?] 1:4 and separations [?] 40 kpc) are only 1.80 +- 0.30 times higher than the SFRs of non-interacting galaxies when averaged over all interactions and all stages of the interaction, in good agreement with other observational works. Our results also agree with hydrodynamical simulations of galaxy interactions, which produce some mergers with large bursts of star formation on [?]100 Myr timescales, but only a modest SFR enhancement when averaged over the entire merger timescale. We demonstrate that these results imply that only [?]10% of star formation at 0.4 [?] z [?] 0.8 is triggered directly by major mergers and interactions; these events are not important factors in the build-up of stellar mass since z = 1.

Published
2009

34. OBSCURED STAR FORMATION IN INTERMEDIATE-DENSITY ENVIRONMENTS: A SPITZER STUDY OF THE ABELL 901/902 SUPERCLUSTER

Author

Gallazzi, Anna, Bell, Eric F., Wolf, Christian, Gray, Meghan E., Papovich, Casey, Barden, Marco, Peng, Chien Y., Meisenheimer, Klaus, Heymans, Catherine, van, Eelco, Gilmour, Rachel, Balogh, Michael, McIntosh, Daniel H., Bacon, David, Barazza, Fabio D., Bohm, Asmus, R, John A., Haussler, Boris, Jahnke, Knud, Jogee, Shardha, Lane, Kyle, Robaina, Aday R., Sanchez, Sebastian F., Taylor, Andy, Wisotzki, Lutz, and Zheng, Xianzhong

Abstract

We explore the amount of obscured star formation as a function of environment in the Abell 901/902 (A901/902) supercluster at z = 0.165 in conjunction with a field sample drawn from the A901 and CDFS fields, imaged with the Hubble Space Telescope as part of the Space Telescope A901/902 Galaxy Evolution Survey and Galaxy Evolution from Morphology and Spectral Energy Distributions (SEDs) Survey. We combine the COMBO-17 near-UV/optical SED with Spitzer 24 m photometry to estimate both the unobscured and obscured star formation in galaxies with M * > 1010 M . We find that the star formation activity in massive galaxies is suppressed in dense environments, in agreement with previous studies. Yet, nearly 40% of the star-forming (SF) galaxies have red optical colors at intermediate and high densities. These red systems are not starbursting; they have star formation rates (SFRs) per unit stellar mass similar to or lower than blue SF galaxies. More than half of the red SF galaxies have low infrared-to-ultraviolet (IR-to-UV) luminosity ratios, relatively high Sersic indices, and they are equally abundant at all densities. They might be gradually quenching their star formation, possibly but not necessarily under the influence of gas-removing environmental processes. The other [?]40% of the red SF galaxies have high IR-to-UV luminosity ratios, indicative of high dust obscuration. They have relatively high specific SFRs and are more abundant at intermediate densities. Our results indicate that while there is an overall suppression in the SF galaxy fraction with density, the small amount of star formation surviving the cluster environment is to a large extent obscured, suggesting that environmental interactions trigger a phase of obscured star formation, before complete quenching.

Published
2009

35. Color, Structure, and Star Formation History of Dwarf Galaxies over the Last ~3 Gyr with GEMS and SDSS

Author

Barazza, Fabio D., Jogee, Shardha, Rix, Walter, Barden, Marco, Bell, Eric F., R, John A., McIntosh, Daniel H., Meisenheimer, Klaus, Peng, Chien Y., and Wolf, Christian

Abstract

We present a study of the colors, structural properties, and star formation histories for a sample of ~1600 dwarfs over look-back times of ~3 Gyr (z = 0.002-0.25). The sample consists of 401 distant dwarfs drawn from the Galaxy Evolution from Morphologies and SEDs (GEMS) survey, which provides high-resolution Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) images and accurate redshifts, and also 1291 dwarfs at 10-90 Mpc compiled from the Sloan Digital Sky Survey (SDSS). The sample is complete down to an effective surface brightness of 22 mag arcsec-2 in z and includes dwarfs with Mg = -18.5 to -14 mag. Rest-frame luminosities in Johnson UBV and SDSS ugr filters are provided by the COMBO-17 survey, and structural parameters have been determined by Sersic fits. We find that the GEMS dwarfs are bluer than the SDSS dwarfs by ~0.13 mag in g - r, which is consistent with the color evolution over ~2 Gyr of star formation histories involving moderate starbursts and long periods of continuous star formation. The full color range of the samples cannot be reproduced by single starbursts of different masses or long periods of continuous star formation alone. Furthermore, an estimate of the mechanical luminosities needed for the gas in the GEMS dwarfs to be completely removed from the galaxies shows that a significant number of low-luminosity dwarfs are susceptible to such a complete gas loss, if they would experience a starburst. On the other hand, a large fraction of more luminous dwarfs is likely to retain their gas. We also estimate the star formation rates per unit area for the GEMS dwarfs and find good agreement with the values for local dwarfs.

Published
2006

36. The Evolution of Early-Type Red Galaxies with the GEMS Survey: Luminosity-Size and Stellar Mass-Size Relations Since z = 1

Author

McIntosh, Daniel H., Bell, Eric F., Rix, Walter, Wolf, Christian, Heymans, Catherine, Peng, Chien Y., Somerville, Rachel S., Barden, Marco, W, Steven V., Borch, Andrea, R, John A., Haussler, Boris, Jahnke, Knud, Jogee, Shardha, Meisenheimer, Klaus, Sanchez, Sebastian F., and Wisotzki, Lutz

Abstract

We combine imaging from the Hubble Space Telescope Advanced Camera for Surveys, as part of the GEMS (Galaxy Evolution from Morphologies and SEDs) survey, with redshifts and rest-frame quantities from COMBO-17 to study the evolution of morphologically early-type galaxies with red colors since z = 1. From 0.deg5 x 0.deg5 imaging, we draw a large sample of 728 galaxies with centrally concentrated radial profiles (i.e., n [?] 2.5 from Sersic fits) and rest-frame (U - V) colors on the red sequence. We explore how the correlations of rest-frame V-band luminosity and of stellar mass with intrinsic half-light size change over the last half of cosmic time. By appropriate comparison with the well-defined local relations from the Sloan Digital Sky Survey, we find that the luminosity-size and stellar mass-size relations evolve in a manner that is consistent with the passive aging of ancient stellar populations. By itself, this result is consistent with a completely passive evolution of the red early-type galaxy population. If instead, as demonstrated by a number of recent surveys, the early-type galaxy population builds up in mass by roughly a factor of 2 since z ~ 1, our results imply that new additions to the early-type galaxy population follow similar luminosity-size and stellar mass-size correlations, compared to the older subset of early-type galaxies. Adding early-type galaxies to the red sequence through the fading of previously prominent disks appears to be consistent with the data. Through comparison with models, the role of dissipationless merging is limited to <1 major merger on average since z = 1 for the most massive galaxies. Predictions from models of gas-rich mergers are not yet mature enough to allow a detailed comparison to our observations. We find tentative evidence that the amount of luminosity evolution depends on galaxy stellar mass, such that the least massive galaxies show stronger luminosity evolution compared to more massive early types. This could reflect a different origin of low-mass early-type galaxies and/or younger stellar populations; the present data are insufficient to discriminate between these possibilities.

Published
2005

37. Nearly 5000 Distant Early-Type Galaxies in COMBO-17: A Red Sequence and Its Evolution since z ~ 1

Author

Bell, Eric F., Wolf, Christian, Meisenheimer, Klaus, Rix, Walter, Borch, Andrea, Dye, Simon, Kleinheinrich, Martina, Wisotzki, Lutz, and McIntosh, Daniel H.

Abstract

We present the rest-frame colors and luminosities of ~25,000 mR [?] 24 galaxies in the redshift range 0.2 < z [?] 1.1 drawn from 0.78 deg2 of the COMBO-17 survey (Classifying Objects by Medium-Band Observations in 17 Filters). We find that the rest-frame color distribution of these galaxies is bimodal at all redshifts out to z ~ 1. This bimodality permits a model-independent definition of red early-type galaxies and blue late-type galaxies at any given redshift. The colors of the blue peak become redder toward the present day, and the number density of blue luminous galaxies has dropped strongly since z ~ 1. Focusing on the red galaxies, we find that they populate a color-magnitude relation. Such red sequences have been identified in galaxy cluster environments, but our data show that such a sequence exists over this redshift range even when averaging over all environments. The mean color of the red galaxy sequence evolves with redshift in a way that is consistent with the aging of an ancient stellar population. The rest-frame B-band luminosity density in red galaxies evolves only mildly with redshift in a L-dominated cold dark matter universe. When we account for the change in stellar mass-to-light ratio implied by the redshift evolution in red galaxy colors, the COMBO-17 data indicate an increase in stellar mass on the red sequence by a factor of 2 since z ~ 1. The largest source of uncertainty is large-scale structure, implying that considerably larger surveys are necessary to further refine this result. We explore mechanisms that may drive this evolution in the red galaxy population, finding that both galaxy merging and truncation of star formation in some fraction of the blue star-forming population are required to fully explain the properties of these galaxies.

Published
2004

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