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Title: How robust are the size measurements of high-redshift compact galaxies?

Massive quiescent galaxies at z ≈ 2 are apparently much more compact than galaxies of comparable mass today. How robust are these size measurements? We perform comprehensive simulations to determine possible biases and uncertainties in fitting single-component light distributions to real galaxies. In particular, we examine the robustness of the measurements of the luminosity, size, and other structural parameters. We devise simulations with increasing realism to systematically disentangle effects due to the technique (specifically using GALFIT) and the intrinsic structures of the galaxies. By accurately capturing the detailed substructures of nearby elliptical galaxies and then rescaling their sizes and signal-to-noise to mimic galaxies at different redshifts, we confirm that the massive quiescent galaxies at z ≈ 2 are significantly more compact intrinsically than their local counterparts. Their observed compactness is not a result of missing faint outer light due to systematic errors in modeling. In fact, we find that fitting multi-component galaxies with a single Sérsic profile, the procedure most commonly adopted in the literature, biases the inferred sizes higher by up to 10%-20%, which accentuates the amount of size evolution required. If the sky estimation has been done robustly and the model for the point-spread function is fairly accurate,more » GALFIT can retrieve the properties of single-component galaxies over a wide range of signal-to-noise ratios without introducing any systematic errors.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4]
  1. University of California, Riverside 900 University Avenue, Riverside, CA 92521 (United States)
  2. The Observatories of the Carnegie Institution for Science 813 Santa Barbara Street, Pasadena, CA 91101 (United States)
  3. Giant Magellan Telescope Organization 251 South Lake Avenue, Suite 300 Pasadena, CA 91101 (United States)
  4. School of Space Science and Astronomy, Nanjing University, Nanjing 210093 (China)
Publication Date:
OSTI Identifier:
22356834
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 787; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; DISTRIBUTION; EVOLUTION; GALAXIES; LUMINOSITY; MASS; PHOTOMETRY; RED SHIFT; SIGNAL-TO-NOISE RATIO; SIMULATION; SKY; VISIBLE RADIATION