CAN MINOR MERGING ACCOUNT FOR THE SIZE GROWTH OF QUIESCENT GALAXIES? NEW RESULTS FROM THE CANDELS SURVEY

By A. Newman, Richard S. Ellis, K. Bundy, T. Treu. 2011

318 citations recorded by the source corpus.

The presence of extremely compact galaxies at z ∼ 2 and their subsequent growth in physical size has been the cause of much puzzlement. We revisit the question using deep infrared Wide Field Camera 3 data to probe the rest-frame optical structure of 935 galaxies selected with 0.4 < z < 2.5 and stellar masses M* > 1010.7 M☉ in the UKIRT Ultra Deep Survey and GOODS-South fields of the CANDELS survey. At each redshift, the most compact sources are those with little or no star formation, and the mean size of these systems at fixed stellar mass grows by a factor of 3.5 ± 0.3 over this redshift interval. The data are sufficiently deep to identify companions to these hosts whose stellar masses are ten times smaller. By searching for these around 404 quiescent hosts within a physical annulus 10 h−1 kpc < R < 30 h−1 kpc, we estimate the minor merger rate over 0.4 < z < 2. We find that 13%–18% of quiescent hosts have likely physical companions with stellar mass ratios of 0.1 or greater. Mergers of these companions will typically increase the host mass by 6% ± 2% per merger timescale. We estimate the minimum growth rate necessary to explain the declining abundance of compact galaxies. Using a simple model motivated by recent numerical simulations, we then assess whether mergers of the faint companions with their hosts are sufficient to explain this minimal rate. We find that mergers may explain most of the size evolution observed at z ≲ 1 if a relatively short merger timescale is assumed, but the rapid growth seen at higher redshift likely requires additional physical processes.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/1ca629170063995c8ba9ed257d7c08baa55307bf

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Citations in the corpus

THE DENSITY PROFILES OF MASSIVE, RELAXED GALAXY CLUSTERS. II. SEPARATING LUMINOUS AND DARK MATTER IN CLUSTER CORES (2012, result): “This size scale is indeed similar to the observed sizes of very massive galaxies at z & 2.5 (e.g., Trujillo et al. 2006; van Dokkum et al. 2008; Newman et al. 2012).”
Theoretical Challenges in Galaxy Formation (2016, background): “Even at high redshift the launching sites of star formation driven (Newman et al. 2012b) and AGN driven (Genzel et al. 2014) winds can now be resolved with modern instruments.”
FORMING COMPACT MASSIVE GALAXIES (2015, methodology): “5 = 0.67 used by Barro et al. (2013) was chosen to be consistent with the slope of the size-mass relation of quiescent galaxies as found by Newman et al. (2012).”
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OBSCURATION-DEPENDENT EVOLUTION OF ACTIVE GALACTIC NUCLEI (2015, methodology): “Spectroscopic redshift measurements of X-ray sources in the AEGIS field are extracted from the compilation presented in Nandra et al. (submitted) which included also the DEEP2 (Newman et al. 2012) and DEEP3 galaxy redshift surveys (Cooper et al. 2011, 2012) as well as observations carried out at the”
OVERVIEW OF THE SDSS-IV MaNGA SURVEY: MAPPING NEARBY GALAXIES AT APACHE POINT OBSERVATORY (2014, background): “Direct measures, however, suggest that the merger frequency may be too low (Bundy et al. 2009; Newman et al. 2012), motivating further tests of merger-driven scenarios.”
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The ATLAS3D project – XX. Mass–size and mass–σ distributions of early-type galaxies: bulge fraction drives kinematics, mass-to-light ratio, molecular gas fraction and stellar initial mass function (2012, background): “…in different samples of nearby galaxies by Valentinuzzi et al. (2010) and Napolitano, Romanowsky & Tortora (2010), and a similar trend, with star-forming galaxies being larger than passive ones was found in place from redshift z ∼ 2.5 (Williams et al. 2010b; Wuyts et al. 2011; Newman et al. 2012).”
Near infrared spectroscopy and star-formation histories of 3 ≤ z ≤ 4 quiescent galaxies (2018, background): “…(HST) simultaneously showed that distant QGs also display “de Vaucouleurs (1948)”-type density profiles, and effective radii getting increasingly larger with time possibly as a result of dry merging (e.g., van Dokkum et al. 2008; Newman et al. 2012; Muzzin et al. 2012; van der Wel et al. 2014b).”
THE DENSITY PROFILES OF MASSIVE, RELAXED GALAXY CLUSTERS. I. THE TOTAL DENSITY OVER THREE DECADES IN RADIUS (2012, background): “For example, a simple extrapolation of the observed stellar mass–size relation at z ≈ 2.5 (Newman et al. 2012) would yield a size of Re ∼ 2−6 kpc for likely progenitors.19 Indirect support for this comes from our observation (Figure 15) that the mass contained in the inner 5 kpc – mostly stars, but…”
THE MOSFIRE DEEP EVOLUTION FIELD (MOSDEF) SURVEY: REST-FRAME OPTICAL SPECTROSCOPY FOR ∼1500 H-SELECTED GALAXIES AT 1.37 ≤ z ≤ 3.8 ?> (2014, background): “…grow inside out, but the physical mechanism (e.g., minor mergers, progenitor bias, cold streams and in situ star formation) responsible for the growth is still subject to debate (e.g., van de Sande et al. 2013; Newman et al. 2012a; Carollo et al. 2013; Dutton et al. 2011; van Dokkum et al. 2013).”