Caputi, K. I. and Kovač, K. and Bolzonella, M. and Lilly, S. J. and Zamorani, G. and Aussel, H. and Sanders, D. and Bardelli, S. and Bongiorno, A. and Contini, T. and Coppa, G. and Cucciati, O. and de la Torre, S. and de Ravel, L. and Franzetti, P. and Frayer, D. and Garilli, B. and Iovino, A. and Kampczyk, P. and Kneib, J. -P. and Knobel, C. and Lamareille, F. and Le Borgne, J. -F. and Le Brun, V. and Le Fèvre, O. and Le Floc’h, E. and Leauthaud, A. and Maier, C. and Mainieri, V. and Mignoli, M. and Pellò, R. and Peng, Y. and Pérez-Montero, E. and Ricciardelli, E. and Salvato, M. and Scodeggio, M. and Scoville, N. and Silverman, J. and Surace, J. and Tanaka, M. and Tasca, L. and Tresse, L. and Vergani, D. and Zucca, E. and Abbas, U. and Bottini, D. and Capak, P. and Cappi, A. and Carollo, M. and Cassata, P. and Cimatti, A. and Fumana, M. and Ilbert, O. and Kartaltepe, J. and Maccagni, D. and Marinoni, C. and McCracken, H. and Memeo, P. and Meneux, B. and Oesch, P. and Porciani, C. and Pozzetti, L. and Renzini, A. and Scaramella, R. and Scarlata, C. (2009) The close environment of 24 μm galaxies at 0.6 < z < 1.0 in the cosmos field. Astrophysical Journal, 691 (1). pp. 91-97. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20090417-103246449
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We investigate the close environment of 203 Spitzer 24 μm -selected sources at 0.6 < z < 1.0 using zCOSMOS-bright redshifts and spectra of I < 22.5 AB mag galaxies, over 1.5 deg^2 of the COSMOS field. We quantify the degree of passivity of the luminous and ultra-luminous IR galaxy (LIRG and ULIRG, respectively) environments by analyzing the fraction of close neighbors with Dn(4000)>1.4. We find that LIRGs at 0.6 < z < 0.8 live in more passive environments than those of other optical galaxies that have the same stellar mass distribution. Instead, ULIRGs inhabit more active regions (e.g., LIRGs and ULIRGs at 0.6 < z < 0.8 have, respectively, (42.0 ± 4.9)% and (24.5 ± 5.9)% of neighbors with Dn(4000)>1.4 within 1 Mpc and ±500 km s^–1). The contrast between the activities of the close environments of LIRGs and ULIRGs appears especially enhanced in the COSMOS field density peak at z ~ 0.67, because LIRGs on this peak have a larger fraction of passive neighbors, while ULIRGs have as active close environments as those outside the large-scale structure. The differential environmental activity is related to the differences in the distributions of stellar mass ratios between LIRGs/ULIRGs and their close neighbors, as well as in the general local density fields. At 0.8 < z < 1.0, instead, we find no differences in the environment densities of ULIRGs and other similarly massive galaxies, in spite of the differential activities. We discuss a possible scenario to explain these findings.
|Additional Information:||© 2009. Received 2008 June 6; accepted 2008 September 19; published 2009 January 7. This paper is based on observations made with the VIMOS spectrograph on the VLT telescope, undertaken at the European Southern Observatory (ESO) under Large Program 175.A-0839, and also based on observations made with the Spitzer Observatory, which is operated under NASA contract 1407.|
|Subject Keywords:||galaxies: evolution – infrared: galaxies|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Marie Noren|
|Deposited On:||21 Apr 2009 22:35|
|Last Modified:||26 Dec 2012 10:57|
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