Rights statement: This is an author-created, un-copyedited version of an article accepted for publication/published in The Astrophysical Journal. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at doi: 10.3847/1538-4357/ab5fd9
Accepted author manuscript, 681 KB, PDF document
Available under license: CC BY-NC: Creative Commons Attribution-NonCommercial 4.0 International License
Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - The colors and sizes of recently quenched galaxies
T2 - a result of compact starburst before quenching
AU - Wu, Po-Feng
AU - Wel, Arjen van der
AU - Bezanson, Rachel
AU - Gallazzi, Anna
AU - Pacifici, Camilla
AU - Straatman, Caroline
AU - Barisic, Ivana
AU - Bell, Eric F.
AU - Chauke, Priscilla
AU - D'Eugenio, Francesco
AU - Franx, Marijn
AU - Muzzin, Adam
AU - Sobral, David
AU - Houdt, Josha van
N1 - This is an author-created, un-copyedited version of an article accepted for publication/published in The Astrophysical Journal. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at doi: 10.3847/1538-4357/ab5fd9
PY - 2020/1/10
Y1 - 2020/1/10
N2 - We analyze the colors and sizes of 32 quiescent (UVJ-selected) galaxies with strong Balmer absorption (EW(Hδ) ≥ 4 ̊A) at z ∼ 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 ∼ 100 Myr that produce ∼ 10% to more than 100% of the pre-existing 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; multi-wavelength 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 shut-down of star-formation activities at z ∼ 0.8.
AB - We analyze the colors and sizes of 32 quiescent (UVJ-selected) galaxies with strong Balmer absorption (EW(Hδ) ≥ 4 ̊A) at z ∼ 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 ∼ 100 Myr that produce ∼ 10% to more than 100% of the pre-existing 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; multi-wavelength 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 shut-down of star-formation activities at z ∼ 0.8.
KW - Galaxy structure
KW - Galaxy colors
KW - Galaxy evolution
KW - Galaxy mergers
KW - Galaxy quenching
KW - Galaxy stellar content
KW - Galaxy formation
U2 - 10.3847/1538-4357/ab5fd9
DO - 10.3847/1538-4357/ab5fd9
M3 - Journal article
VL - 888
JO - The Astrophysical Journal
JF - The Astrophysical Journal
SN - 0004-637X
IS - 2
M1 - 77
ER -