Details

Autor(en) / Beteiligte

• Simons, Raymond C.
• Kassin, Susan A.
• Weiner, Benjamin J.
• Faber, Sandra M.
• Trump, Jonathan R.
• Heckman, Timothy M.
• Koo, David C.
• Pacifici, Camilla
• Primack, Joel R.
• Snyder, Gregory F.
• Vega, Alexander de la

Titel

z ∼ 2: An Epoch of Disk Assembly

Ist Teil von

• The Astrophysical journal, 2017-07, Vol.843 (1), p.46

Ort / Verlag

Philadelphia: The American Astronomical Society

Erscheinungsjahr

2017

Quelle

Free E-Journal (出版社公開部分のみ）

Beschreibungen/Notizen

• We explore the evolution of the internal gas kinematics of star-forming galaxies from the peak of cosmic star formation at z ∼ 2 to today. Measurements of galaxy rotation velocity Vrot, which quantify ordered motions, and gas velocity dispersion g , which quantify disordered motions, are adopted from the DEEP2 and SIGMA surveys. This sample covers a continuous baseline in redshift over 0.1 < z < 2.5 , spanning 10 Gyr. At low redshift, nearly all sufficiently massive star-forming galaxies are rotationally supported ( V rot > g ). By z = 2, 50% and 70% of galaxies are rotationally supported at low ( 10 9 - 10 10 M ) and high ( 10 10 - 10 11 M ) stellar mass, respectively. For V rot > 3 g , the percentage drops below 35% for all masses. From z = 2 to now, galaxies exhibit remarkably smooth kinematic evolution on average. All galaxies tend toward rotational support with time, and higher-mass systems reach it earlier. This is largely due to a mass-independent decline in g by a factor of 3 since z = 2. Over the same time period, Vrot increases by a factor of 1.5 in low-mass systems but does not evolve at high mass. These trends in Vrot and g are at a fixed stellar mass and therefore should not be interpreted as evolutionary tracks for galaxy populations. When populations are linked in time via abundance matching, g declines as before and Vrot strongly increases with time for all galaxy populations, enhancing the evolution in V rot g . These results indicate that z = 2 is a period of disk assembly, during which strong rotational support is only just beginning to emerge.