FORMING COMPACT MASSIVE GALAXIES

By P. V. van Dokkum, E. Nelson, M. Franx, P. Oesch, Ivelina G. Momcheva, G. Brammer, N. F. Förster Schreiber, R. Skelton, K. Whitaker, A. van der Wel and 6 more. 2015

184 citations recorded by the source corpus.

In this paper we study a key phase in the formation of massive galaxies: the transition of star-forming galaxies into massive (Mstars ∼ 1011M⊙), compact (re ∼ 1 kpc) quiescent galaxies, which takes place from z ∼ 3 to z ∼ 1.5. We use HST grism redshifts and extensive photometry in all five 3D-HST/CANDELS fields, more than doubling the area used previously for such studies, and combine these data with Keck MOSFIRE and NIRSPEC spectroscopy. We first confirm that a population of massive, compact, star-forming galaxies exists at z ≳ 2, using K-band spectroscopy of 25 of these objects at 2.0 < z < 2.5. They have a median [N ii]/Hα ratio of 0.6, are highly obscured with SFR(tot)/SFR(Hα) ∼10, and have a large range of observed line widths. We infer from the kinematics and spatial distribution of Hα that the galaxies have rotating disks of ionized gas that are a factor of ∼2 more extended than the stellar distribution. By combining measurements of individual galaxies, we find that the kinematics are consistent with a nearly Keplerian fall-off from Vrot ∼ 500 km s−1 at 1 kpc to Vrot ∼ 250 km s−1 at 7 kpc, and that the total mass out to this radius is dominated by the dense stellar component. Next, we study the size and mass evolution of the progenitors of compact massive galaxies. Even though individual galaxies may have had complex histories with periods of compaction and mergers, we show that the population of progenitors likely followed a simple inside-out growth track in the size–mass plane of Δ log r e ∼ 0.3 Δ log M stars . ?> This mode of growth gradually increases the stellar mass within a fixed physical radius, and galaxies quench when they reach a stellar density or velocity dispersion threshold. As shown in other studies, the mode of growth changes after quenching, as dry mergers take the galaxies on a relatively steep track in the size–mass plane.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/33126ba855b7d8b88fac760df9f8e3c5bcfe436c

How researchers see this paper

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In Astronomy and Astrophysics

1. L. Hernquist
2. P. Hopkins
3. P. V. van Dokkum
4. A. Dekel
5. R. Dav'e
6. Volker Springel
7. T. Naab
8. R. Somerville

In Instrumentation

1. L. Hernquist
2. P. Hopkins
3. P. V. van Dokkum
4. A. Dekel
5. M. Franx
6. R. Dav'e
7. R. Somerville
8. T. Naab

Citations in the corpus

• Size evolution of normal and compact galaxies in the EAGLE simulation (2015, background): “It is thus challenging to establish what becomes of these compact passive galaxies from observational evidence alone (e.g. van Dokkum et al. 2015).”
• THE 3D-HST SURVEY: HUBBLE SPACE TELESCOPE WFC3/G141 GRISM SPECTRA, REDSHIFTS, AND EMISSION LINE MEASUREMENTS FOR ∼100,000 GALAXIES (2015, background): “Nelson et al. (2014) and van Dokkum et al. (2014, 2015) study the formation and evolution of the cores of massive galaxies.”
• The size evolution of star-forming and quenched galaxies in the IllustrisTNG simulation (2017, background): “The velocity values indicated next to these lines are based on the empirical relation describing galaxy velocity dispersion as a function of mass and size (van Dokkum et al. 2015).”
• Near infrared spectroscopy and star-formation histories of 3 ≤ z ≤ 4 quiescent galaxies (2018, background): “The second and third programs (PIs: Oesch, Illingworth) were more broadly targeting massive galaxies at 2 < z < 3.6 identified in the 3DHST catalogs, and quiescent galaxies were not prioritized over star-forming ones (see van Dokkum et al. 2015).”
• Structure and Kinematics of Early-Type Galaxies from Integral Field Spectroscopy (2016, methodology): “The evolution of the distribution of galaxies on the (M∗, Re) plane was interpreted by van Dokkum et al. (2015) using a simple statistical model which tries to capture the dominant mode of growth.”
• Structural and Star-forming Relations since z ∼ 3: Connecting Compact Star-forming and Quiescent Galaxies (2015, background): “However, confining quenching to this evolutionary track would overproduce the number of massive quiescent galaxies (e.g., van Dokkum et al. 2015).”
• Evolution of density profiles in high-z galaxies: compaction and quenching inside-out (2015, background): “…that these high central densities have formed early, before z ∼ 2 (e.g., Wuyts et al. 2012; Saracco et al. 2012; Barro et al. 2013; Patel et al. 2013; van Dokkum et al. 2010, 2013; Barro et al. 2014; van Dokkum et al. 2014; Morishita et al. 2015; Tacchella et al. 2015b; van Dokkum et al. 2015).”
• The SINS/zC-SINF Survey of z ∼ 2 Galaxy Kinematics: SINFONI Adaptive Optics–assisted Data and Kiloparsec-scale Emission-line Properties (2018, background): “…featureless) kinematics, estimates can be obtained for instance from the integrated Hα line width with Vc = σtot(Hα)/0.8 sin(i) (following, e.g., van Dokkum et al. 2015; Wisnioski et al. 2018 but neglecting the contribution from outflowing gas and the explicit split of pressure support; see…”
• Constraining the galaxy–halo connection over the last 13.3 Gyr: star formation histories, galaxy mergers and structural properties (2017, background): “…studies that the evolution of the structural properties of the galaxies played a key role in the quenching of galaxies (Kauffmann et al. 2003a; van Dokkum et al. 2010; Bell et al. 2012; Cheung et al. 2012; Patel et al. 2013; van Dokkum et al. 2014; Barro et al. 2013, 2015; van Dokkum et al. 2015b).”