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Title: Red nuggets grow inside-out: evidence from gravitational lensing

Here, we present a new sample of strong gravitational lens systems where both the foreground lenses and background sources are early-type galaxies. Using imaging from Hubble Space Telescope (HST)/Advanced Camera for Studies (ACS) and Keck/NIRC2, we model the surface brightness distributions and show that the sources form a distinct population of massive, compact galaxies at redshifts 0.4 ≲ z ≲ 0.7, lying systematically below the size–mass relation of the global elliptical galaxy population at those redshifts. These may therefore represent relics of high-redshift red nuggets or their partly evolved descendants. We exploit the magnifying effect of lensing to investigate the structural properties, stellar masses and stellar populations of these objects with a view to understanding their evolution. We model these objects parametrically and find that they generally require two Sérsic components to properly describe their light profiles, with one more spheroidal component alongside a more envelope-like component, which is slightly more extended though still compact. This is consistent with the hypothesis of the inside-out growth of these objects via minor mergers. Lastly, we also find that the sources can be characterized by red-to-blue colour gradients as a function of radius which are stronger at low redshift – indicative of ongoingmore » accretion – but that their environments generally appear consistent with that of the general elliptical galaxy population, contrary to recent suggestions that these objects are pre-dominantly associated with clusters.« less
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9]
  1. Univ. of Cambridge (United Kingdom). Inst. of Astronomy
  2. Univ. of California, Davis, CA (United States). Dept. of Physics
  3. Univ. of California, Los Angeles, CA (United States). Dept. of Physics and Astronomy
  4. Univ. of Auckland (New Zealand). Dept. of Statistics
  5. Univ. of Groningen (The Netherlands). Kapteyn Astronomical Inst.
  6. Univ. de Lyon, Saint-Genis-Laval (France). Centre National de la Recherche Scientifique (CNRS), Centre de Recherche Astrophysique de Lyon
  7. Stanford Univ., CA (United States). Kavli Inst. for Particle Astrophysics and Cosmology
  8. ASTRON, Netherlands Inst. for Radio Astronomy, Dwingeloo (The Netherlands); Kapteyn Astronomical Inst., Groningen (The Netherlands)
  9. Max Planck Society, Garching (Germany). Max Planck Inst. for Astrophysik
Publication Date:
Grant/Contract Number:
AC02-76SF00515; NAS 5-26555
Type:
Accepted Manuscript
Journal Name:
Monthly Notices of the Royal Astronomical Society
Additional Journal Information:
Journal Volume: 465; Journal Issue: 3; Journal ID: ISSN 0035-8711
Publisher:
Royal Astronomical Society
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE; National Aeronautic and Space Administration (NASA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; gravitational lensing; strong galaxies; elliptical and lenticular cD galaxies; evolution galaxies; structure
OSTI Identifier:
1353201