ON SIZES, KINEMATICS, M/L GRADIENTS, AND LIGHT PROFILES OF MASSIVE COMPACT GALAXIES AT z ∼ 2

By S. Wuyts, Thomas J. Cox, C. Hayward, M. Franx, L. Hernquist, P. Hopkins, P. Jonsson, P. V. van Dokkum. 2010

136 citations recorded by the source corpus.

We present a detailed analysis of the structure and resolved stellar populations of simulated merger remnants, and compare them to observations of compact quiescent galaxies at z ∼ 2. We find that major merging is a viable mechanism to produce systems of ∼1011 M☉ and ∼1 kpc size, provided the gas fraction at the time of final coalescence is high (∼40%) and provided that the progenitors are compact star-forming galaxies, as expected at high redshift. Their integrated spectral energy distributions and velocity dispersions are in good agreement with the observations, and their position in the (vmaj/σ, ϵ) diagram traces the upper envelope of the distribution of lower redshift early-type galaxies. The simulated merger remnants show time- and sightline-dependent M/L ratio gradients that result from a superposition of radially dependent stellar age, stellar metallicity, and extinction. The median ratio of the effective radius in rest-frame V-band light to that in mass surface density is ∼2 during the quiescent remnant phase. This is typically expressed by a negative color gradient (i.e., red core), which we expect to correlate with the integrated color of the system. Finally, the simulations differ from the observations in their surface brightness profile shape. The simulated remnants are typically best fit by high (n ≫ 4) Sérsic indices, whereas observed quiescent galaxies at z ∼ 2 tend to be less cuspy (〈n〉 ∼ 2.3). Limiting early star formation in the progenitors may be required to prevent the simulated merger remnants from having extended wings.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/001e23c1da6d593f9caedcbf96bf79f1dfbb965d

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In Astronomy and Astrophysics

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

In Instrumentation

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

Citations in the corpus

• 3D-HST+CANDELS: THE EVOLUTION OF THE GALAXY SIZE–MASS DISTRIBUTION SINCE z = 3 (2014, unknown): “It remains to be seen whether such processes can reproduce the correct stellar density profiles (Wuyts et al. 2010).”
• SMOOTH(ER) STELLAR MASS MAPS IN CANDELS: CONSTRAINTS ON THE LONGEVITY OF CLUMPS IN HIGH-REDSHIFT STAR-FORMING GALAXIES (2012, methodology): “Applications of the SUNRISE radiative transfer code (Jonsson 2006; Jonsson et al. 2010) for an apples to apples comparison between observed and simulated (structural) galaxy properties at z ∼ 2 have been presented by Wuyts et al. (2009; 2010).”
• Submillimetre galaxies in a hierarchical universe: number counts, redshift distribution, and implications for the IMF (2012, background): “…et al. 2003; Dale et al. 2007) galaxies (Jonsson, Groves & Cox 2010); local ULIRGs (Younger et al. 2009); massive, quiescent, compact z ∼ 2 galaxies (Wuyts et al. 2009, 2010); 24- μm-selected galaxies (Narayanan et al. 2010a); K+A/post-starburst galaxies (Snyder et al. 2011) and extended UV discs…”
• CANDELS: THE PROGENITORS OF COMPACT QUIESCENT GALAXIES AT z ∼ 2 (2012, background): “Recent hydrodynamical simulations of mergers have reproduced some of the observed properties of cQGs (Wuyts et al. 2010), if high amounts of cold gas, as observed by Tacconi et al. (2010), are adopted.”
• Early type galaxies have been the predominant morphological class for massive galaxies since only z~1 (2011, methodology): “For massive galaxies this model predicts a rapid formation phase at 2<z<6 dominated by a dissipational in-situ star formation fed by cold flows (Oser et al. 2010; Dekel et al. 2009; Keres et al. 2005) and/or gas rich mergers (Ricciardelli et al. 2010; Wuyts et al. 2010; Bournaud et al. 2011).”
• The formation of massive, compact galaxies at z = 2 in the Illustris simulation (2014, background): “For example, major, gas-rich mergers where tidal torques drive gas rapidly to the centers of galaxies can provoke intense starbursts there, leaving a compact merger remnant behind (Mihos & Hernquist 1996; Hopkins et al. 2008; Wuyts et al. 2010).”
• WHAT DOES A SUBMILLIMETER GALAXY SELECTION ACTUALLY SELECT? THE DEPENDENCE OF SUBMILLIMETER FLUX DENSITY ON STAR FORMATION RATE AND DUST MASS (2010, background): “…et al. 2003; Dale et al. 2007) galaxies (Jonsson et al. 2010); local ULIRGs (Younger et al. 2009a); massive, quiescent, compact z ∼ 2 galaxies (Wuyts et al. 2009, 2010); 24 μm selected galaxies (Narayanan et al. 2010b); K+A/post-starburst galaxies (Snyder et al. 2011); and extended…”
• FORMING COMPACT MASSIVE GALAXIES (2015, background): “…characteristics of compact massive galax- 2 ies, either by mergers that are accompanied by a strong central star burst (e.g., Hopkins et al. 2009b; Wuyts et al. 2010; Wellons et al. 2015), by in-situ formation from highly efficient gas cooling (Naab et al. 2009; Wellons et al. 2015), or by…”
• The Morphologies of Massive Galaxies at 1<z<3 in the CANDELS-UDS Field: Compact Bulges, and the Rise and Fall of Massive Disks (2012, background): “…to the present-day size–mass relation, the existence of such compact objects at early times, while perhaps initially unexpected, is in fact a natural prediction of modern galaxy-formation simulations (e.g. Khochfar & Silk 2006; Obreschkow & Rawlings 2009; Hopkins et al. 2010a; Wuyts et al. 2010).”
• THE COSMOLOGICAL SIZE AND VELOCITY DISPERSION EVOLUTION OF MASSIVE EARLY-TYPE GALAXIES (2011, background): “…merger of massive very gas-rich disks at z & 2 - which has been suggested as a reasonable formation mechanism for compact high-redshift galaxies (Wuyts et al. 2010; Ricciardelli et al. 2010; Bournaud et al. 2011) - followed by passive evolution can be ruled out (Kriek et al. 2008; van Dokkum et…”
• SIZES AND SURFACE BRIGHTNESS PROFILES OF QUIESCENT GALAXIES AT z ∼ 2 (2011, background): “The early formation and subsequent evolution of these massive, compact objects presents a considerable challenge to current models of galaxy formation and evolution (e.g., Wuyts et al. 2010; Oser et al. 2011).”
• The mean star formation rate of X-ray selected active galaxies and its evolution from z~2.5: results from PEP-Herschel (2012, methodology): “We use the models studied by Wuyts et al. (2010) which focus on progenitor galaxies with size and high gas content as expected for z∼2 mergers, as well as a fully analogous set of models which encompass the larger sizes and lower gas content of local mergers (Cox et al. 2006).”
• Star formation in galaxy mergers with realistic models of stellar feedback and the interstellar medium (2012, background): “…molecular filaments (and volumefilling molecular gas near the galaxy centres), with most of the gas mass. 4 Accounting for dust scattering changes the detailed spectrum, but the colours and morphologies in the images are not significantly altered (Jonsson et al. 2006; Wuyts et al. 2009, 2010).”
• Simulations of binary galaxy mergers and the link with fast rotators, slow rotators, and kinematically distinct cores (2011, background): “…studies have indeed shown that the resolution affects the properties of the simulated objects, either in cosmological simulations (Naab et al. 2007; Navarro et al. 2010) or on simulations of star formation in mergers (Cox et al. 2006b; Hopkins et al. 2008; Di Matteo et al. 2008; Wuyts et al. 2010).”
• HYDRODYNAMICS OF HIGH-REDSHIFT GALAXY COLLISIONS: FROM GAS-RICH DISKS TO DISPERSION-DOMINATED MERGERS AND COMPACT SPHEROIDS (2010, background): “Actually, to form ETGs that are about as compact as z ∼ 2 ones, Wuyts et al. (2010) had to start with pre-merger disk galaxies that were twice as compact as our initial disk galaxies, with a disk scale length half as large.”
• Implementation of feedback in smoothed particle hydrodynamics: towards concordance of methods (2012, background): “(B3) In addition, as reported by Wuyts et al. (2010), the value of the accuracy coefficient, η, may play a role in capturing strong shocks, and hence in the convergence of the results.”
• SUBMILLIMETER GALAXIES AS PROGENITORS OF COMPACT QUIESCENT GALAXIES (2014, background): “…gas-rich mergers at high redshift (Wuyts et al. 2010), in which the gas is driven to the center, igniting a massive nuclear starburst, followed by an AGN/QSO phase that quenches the star formation, and leaves behind a compact remnant (Sanders et al. 1988; Hopkins et al. 2006; Wuyts et al. 2010).”
• Theoretical Challenges in Galaxy Formation (2016, result): “…momentum gas is efficiently converted into stars, some of the systems can be remarkably small (also supported by mergers, Bournaud et al. 2011a, Wuyts et al. 2010), very similar to the population of observed high-redshift compact galaxies (Oser et al. 2012, 2010, Sommer-Larsen & Toft 2010,…”
• GALAXY STRUCTURE AND MODE OF STAR FORMATION IN THE SFR–MASS PLANE FROM z ∼ 2.5 TO z ∼ 0.1 (2011, background): “While the excess star formation due to mergers may only amount to 5-10% (Hopkins et al. 2010; Rodighiero et al. 2011), they may play a crucial role in shaping the diversity of galaxies observed both at low and high redshift.”