THE ROLE OF QUENCHING TIME IN THE EVOLUTION OF THE MASS-SIZE RELATION OF PASSIVE GALAXIES FROM THE WISP SURVEY Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555

• Published in: The Astrophysical journal Vol. 824; no. 2
• Main Authors: Zanella, A., Scarlata, C., Corsini, E. M., Bedregal, A. G., Bontà, E. Dalla, Atek, H., Bunker, A. J., Colbert, J ., Dai, Y. S., Henry, A., Malkan, M., Martin, C., Rafelski, M., Rutkowski, M. J., Siana, B., Teplitz, H.
• Format: Journal Article
• Language: English
• Published: The American Astronomical Society 14.06.2016
• Subjects: galaxies: evolution; galaxies: fundamental parameters; galaxies: high-redshift; galaxies: structure
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/0004-637X/824/2/68

ABSTRACT We analyze how passive galaxies at z ∼ 1.5 populate the mass-size plane as a function of their stellar age, to understand if the observed size growth with time can be explained with the appearance of larger quenched galaxies at lower redshift. We use a sample of 32 passive galaxies extracted from the Wide Field Camera 3 Infrared Spectroscopic Parallel (WISP) survey with spectroscopic redshift 1.3 z 2.05, specific star formation rates lower than 0.01 Gyr−1, and stellar masses above 4.5 × 1010 M . All galaxies have spectrally determined stellar ages from fitting of their rest-frame optical spectra and photometry with stellar population models. When dividing our sample into young (age ≤2.1 Gyr) and old (age >2.1 Gyr) galaxies we do not find a significant trend in the distributions of the difference between the observed radius and that predicted by the mass-size relation. This result indicates that the relation between the galaxy age and its distance from the mass-size relation, if it exists, is rather shallow, with a slope −0.6. At face value, this finding suggests that multiple dry and/or wet minor mergers, rather than the appearance of newly quenched galaxies, are mainly responsible for the observed time evolution of the mass-size relation in passive galaxies.