The dependence of galactic outflows on the properties and orientation of zCOSMOS galaxies at z 1

R. Bordoloi, S. J. Lilly, E. Hardmeier, T. Contini, J. P. Kneib, O. Le Fevre, V. Mainieri, A. Renzini, M. Scodeggio, G. Zamorani, S. Bardelli, M. Bolzonella, A. Bongiorno, K. Caputi, C. M. Carollo, O. Cucciati, S. De La Torre, L. De Ravel, B. Garilli, A. IovinoP. Kampczyk, K. Kovač, C. Knobel, F. Lamareille, J. F.Le Borgne, V. Le Brun, C. Maier, M. Mignoli, P. Oesch, R. Pello, Y. Peng, E. Perez Montero, V. Presotto, J. Silverman, M. Tanaka, L. Tasca, L. Tresse, D. Vergani, E. Zucca, A. Cappi, A. Cimatti, G. Coppa, P. Franzetti, A. Koekemoer, M. Moresco, P. Nair, L. Pozzetti

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96 Citations (Scopus)


We present an analysis of cool outflowing gas around galaxies, traced by Mg II absorption lines in the coadded spectra of a sample of 486 zCOSMOS galaxies at 1 ≤ z ≤ 1.5. These galaxies span a range of stellar masses (9.45 ≤ log10[M ∗/M ] ≤ 10.7) and star formation rates (0.14 ≤ log10[SFR/M yr-1] ≤ 2.35). We identify the cool outflowing component in the Mg II absorption and find that the equivalent width of the outflowing component increases with stellar mass. The outflow equivalent width also increases steadily with the increasing star formation rate of the galaxies. At similar stellar masses, the blue galaxies exhibit a significantly higher outflow equivalent width as compared to red galaxies. The outflow equivalent width shows strong correlation with the star formation surface density (ΣSFR) of the sample. For the disk galaxies, the outflow equivalent width is higher for the face-on systems as compared to the edge-on ones, indicating that for the disk galaxies, the outflowing gas is primarily bipolar in geometry. Galaxies typically exhibit outflow velocities ranging from -150 km s-1 -200 km s-1 and, on average, the face-on galaxies exhibit higher outflow velocity as compared to the edge-on ones. Galaxies with irregular morphologies exhibit outflow equivalent width as well as outflow velocities comparable to face on disk galaxies. These galaxies exhibit mass outflow rates >5-7 M yr-1 and a mass loading factor () comparable to the star formation rates of the galaxies.

Original languageEnglish
Article number130
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 2014 Oct 20


  • galaxies: evolution
  • galaxies: high-redshift
  • intergalactic medium
  • ultraviolet: ISM


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