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The colors and sizes of recently quenched galaxies : a result of compact starburst before quenching

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Abstract
We analyze the colors and sizes of 32 quiescent (UVJ-selected) galaxies with strong Balmer absorption (EW(H delta) >= 4 A) at z similar to 0.8 drawn from DR2 of the LEGA-C survey to test the hypothesis that these galaxies experienced compact, central starbursts before quenching. These recently quenched galaxies, usually referred to as post-starburst galaxies, span a wide range of colors, and we find a clear correlation between color and half-light radius, such that bluer galaxies are smaller. We build simple toy models to explain this correlation: a normal star-forming disk plus a central, compact starburst component. Bursts with exponential decay timescale of similar to 100 Myr that produce similar to 10% to more than 100% of the preexisting masses can reproduce the observed correlation. More significant bursts also produce bluer and smaller descendants. Our findings imply that when galaxies shut down star formation rapidly, they generally had experienced compact, starburst events and that the large, observed spread in sizes and colors mostly reflects a variety of burst strengths. Recently quenched galaxies should have younger stellar ages in the centers; multiwavelength data with high spatial resolution are required to reveal the age gradient. Highly dissipative processes should be responsible for this type of formation history. While determining the mechanisms for individual galaxies is challenging, some recently quenched galaxies show signs of gravitational interactions, suggesting that mergers are likely an important mechanism in triggering the rapid shutdown of star formation activities at z similar to 0.8.
Keywords
Space and Planetary Science, Astronomy and Astrophysics, Galaxy structure, Galaxy colors, Galaxy evolution, Galaxy mergers, Galaxy quenching, Galaxy stellar content, Galaxy formation, STAR-FORMATION HISTORIES, GIANT BRANCH STARS, POST-STARBURST, RED-SEQUENCE, BLACK-HOLES, TIME-SCALES, EVOLUTION, BLUE, POPULATION, CLUSTERS

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Citation

Please use this url to cite or link to this publication:

MLA
Wu, Po-Feng, et al. “The Colors and Sizes of Recently Quenched Galaxies : A Result of Compact Starburst before Quenching.” ASTROPHYSICAL JOURNAL, vol. 888, no. 2, 2020, doi:10.3847/1538-4357/ab5fd9.
APA
Wu, P.-F., van der Wel, A., Bezanson, R., Gallazzi, A., Pacifici, C., Straatman, C., … van Houdt, J. (2020). The colors and sizes of recently quenched galaxies : a result of compact starburst before quenching. ASTROPHYSICAL JOURNAL, 888(2). https://doi.org/10.3847/1538-4357/ab5fd9
Chicago author-date
Wu, Po-Feng, Arjen van der Wel, Rachel Bezanson, Anna Gallazzi, Camilla Pacifici, Caroline Straatman, Ivana Barišić, et al. 2020. “The Colors and Sizes of Recently Quenched Galaxies : A Result of Compact Starburst before Quenching.” ASTROPHYSICAL JOURNAL 888 (2). https://doi.org/10.3847/1538-4357/ab5fd9.
Chicago author-date (all authors)
Wu, Po-Feng, Arjen van der Wel, Rachel Bezanson, Anna Gallazzi, Camilla Pacifici, Caroline Straatman, Ivana Barišić, Eric F. Bell, Priscilla Chauke, Francesco D’Eugenio, Marijn Franx, Adam Muzzin, David Sobral, and Josha van Houdt. 2020. “The Colors and Sizes of Recently Quenched Galaxies : A Result of Compact Starburst before Quenching.” ASTROPHYSICAL JOURNAL 888 (2). doi:10.3847/1538-4357/ab5fd9.
Vancouver
1.
Wu P-F, van der Wel A, Bezanson R, Gallazzi A, Pacifici C, Straatman C, et al. The colors and sizes of recently quenched galaxies : a result of compact starburst before quenching. ASTROPHYSICAL JOURNAL. 2020;888(2).
IEEE
[1]
P.-F. Wu et al., “The colors and sizes of recently quenched galaxies : a result of compact starburst before quenching,” ASTROPHYSICAL JOURNAL, vol. 888, no. 2, 2020.
@article{8677242,
  abstract     = {We analyze the colors and sizes of 32 quiescent (UVJ-selected) galaxies with strong Balmer absorption (EW(H delta) >= 4 A) at z similar to 0.8 drawn from DR2 of the LEGA-C survey to test the hypothesis that these galaxies experienced compact, central starbursts before quenching. These recently quenched galaxies, usually referred to as post-starburst galaxies, span a wide range of colors, and we find a clear correlation between color and half-light radius, such that bluer galaxies are smaller. We build simple toy models to explain this correlation: a normal star-forming disk plus a central, compact starburst component. Bursts with exponential decay timescale of similar to 100 Myr that produce similar to 10% to more than 100% of the preexisting masses can reproduce the observed correlation. More significant bursts also produce bluer and smaller descendants. Our findings imply that when galaxies shut down star formation rapidly, they generally had experienced compact, starburst events and that the large, observed spread in sizes and colors mostly reflects a variety of burst strengths. Recently quenched galaxies should have younger stellar ages in the centers; multiwavelength data with high spatial resolution are required to reveal the age gradient. Highly dissipative processes should be responsible for this type of formation history. While determining the mechanisms for individual galaxies is challenging, some recently quenched galaxies show signs of gravitational interactions, suggesting that mergers are likely an important mechanism in triggering the rapid shutdown of star formation activities at z similar to 0.8.},
  articleno    = {77},
  author       = {Wu, Po-Feng and van der Wel, Arjen and Bezanson, Rachel and Gallazzi, Anna and Pacifici, Camilla and Straatman, Caroline and Barišić, Ivana and Bell, Eric F. and Chauke, Priscilla and D'Eugenio, Francesco and Franx, Marijn and Muzzin, Adam and Sobral, David and van Houdt, Josha},
  issn         = {0004-637X},
  journal      = {ASTROPHYSICAL JOURNAL},
  keywords     = {Space and Planetary Science,Astronomy and Astrophysics,Galaxy structure,Galaxy colors,Galaxy evolution,Galaxy mergers,Galaxy quenching,Galaxy stellar content,Galaxy formation,STAR-FORMATION HISTORIES,GIANT BRANCH STARS,POST-STARBURST,RED-SEQUENCE,BLACK-HOLES,TIME-SCALES,EVOLUTION,BLUE,POPULATION,CLUSTERS},
  language     = {eng},
  number       = {2},
  pages        = {12},
  title        = {The colors and sizes of recently quenched galaxies : a result of compact starburst before quenching},
  url          = {http://dx.doi.org/10.3847/1538-4357/ab5fd9},
  volume       = {888},
  year         = {2020},
}

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