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Fast and slow paths to quiescence : ages and sizes of 400 quiescent galaxies from the LEGA-C survey

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Abstract
We analyze the stellar age indicators (D(n)4000 and EW(H delta)) and sizes of 467 quiescent galaxies with M-* >= 10(10)M(circle dot) at z similar to 0.7 drawn from DR2 of the LEGA-C survey. Interpreting index variations in terms of equivalent single stellar population age, we find that the median stellar population is younger for larger galaxies at fixed stellar mass. The effect is significant, yet small; the ages of the larger and smaller subsets differ by only < 500 Myr, much less than the age variation among individual galaxies (similar to 1.5 Gyr). At the same time, post-starburst galaxies-those that experienced recent and rapid quenching events-are much smaller than expected based on the global correlation between age and size of normal quiescent galaxies. These coexisting trends unify seemingly contradictory results in the literature; the complex correlations between size and age indicators revealed by our large sample of galaxies with high-quality spectra suggest that there are multiple evolutionary pathways to quiescence. Regardless of the specific physical mechanisms responsible for the cessation of star formation in massive galaxies, the large scatter in D(n)4000 and EW(H delta) immediately implies that galaxies follow a large variety of evolutionary pathways. On the one hand, we see evidence for a process that slowly shuts off star formation and transforms star-forming galaxies to quiescent galaxies without necessarily changing their structures. On the other hand, there is likely a mechanism that rapidly quenches galaxies, an event that coincides with dramatic structural changes, producing post-starburst galaxies that can be smaller than their progenitors.
Keywords
POST-STARBURST GALAXIES, STAR-FORMATION HISTORIES, SIMILAR-TO 1, ACTIVE, GALACTIC NUCLEI, DIGITAL SKY SURVEY, SUPERMASSIVE BLACK-HOLES, INITIAL, MASS FUNCTION, GAS DEPLETION TIME, VLT DEEP SURVEY, DISK GALAXIES, galaxies: evolution, galaxies: formation, galaxies: high-redshift, galaxies: stellar content, galaxies: structure

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MLA
Wu, Po-Feng et al. “Fast and Slow Paths to Quiescence : Ages and Sizes of 400 Quiescent Galaxies from the LEGA-C Survey.” ASTROPHYSICAL JOURNAL 868.1 (2018): n. pag. Print.
APA
Wu, P.-F., van der Wel, A., Bezanson, R., Gallazzi, A., Pacifici, C., Straatman, C., Barisic, I., et al. (2018). Fast and slow paths to quiescence : ages and sizes of 400 quiescent galaxies from the LEGA-C survey. ASTROPHYSICAL JOURNAL, 868(1).
Chicago author-date
Wu, Po-Feng, Arjen van der Wel, Rachel Bezanson, Anna Gallazzi, Camilla Pacifici, Caroline Straatman, Ivana Barisic, et al. 2018. “Fast and Slow Paths to Quiescence : Ages and Sizes of 400 Quiescent Galaxies from the LEGA-C Survey.” Astrophysical Journal 868 (1).
Chicago author-date (all authors)
Wu, Po-Feng, Arjen van der Wel, Rachel Bezanson, Anna Gallazzi, Camilla Pacifici, Caroline Straatman, Ivana Barisic, Eric F Bell, Priscilla Chauke, Josha van Houdt, Marijn Franx, Adam Muzzin, David Sobral, and Vivienne Wild. 2018. “Fast and Slow Paths to Quiescence : Ages and Sizes of 400 Quiescent Galaxies from the LEGA-C Survey.” Astrophysical Journal 868 (1).
Vancouver
1.
Wu P-F, van der Wel A, Bezanson R, Gallazzi A, Pacifici C, Straatman C, et al. Fast and slow paths to quiescence : ages and sizes of 400 quiescent galaxies from the LEGA-C survey. ASTROPHYSICAL JOURNAL. 2018;868(1).
IEEE
[1]
P.-F. Wu et al., “Fast and slow paths to quiescence : ages and sizes of 400 quiescent galaxies from the LEGA-C survey,” ASTROPHYSICAL JOURNAL, vol. 868, no. 1, 2018.
@article{8620727,
  abstract     = {We analyze the stellar age indicators (D(n)4000 and EW(H delta)) and sizes of 467 quiescent galaxies with M-* >= 10(10)M(circle dot) at z similar to 0.7 drawn from DR2 of the LEGA-C survey. Interpreting index variations in terms of equivalent single stellar population age, we find that the median stellar population is younger for larger galaxies at fixed stellar mass. The effect is significant, yet small; the ages of the larger and smaller subsets differ by only < 500 Myr, much less than the age variation among individual galaxies (similar to 1.5 Gyr). At the same time, post-starburst galaxies-those that experienced recent and rapid quenching events-are much smaller than expected based on the global correlation between age and size of normal quiescent galaxies. These coexisting trends unify seemingly contradictory results in the literature; the complex correlations between size and age indicators revealed by our large sample of galaxies with high-quality spectra suggest that there are multiple evolutionary pathways to quiescence. Regardless of the specific physical mechanisms responsible for the cessation of star formation in massive galaxies, the large scatter in D(n)4000 and EW(H delta) immediately implies that galaxies follow a large variety of evolutionary pathways. On the one hand, we see evidence for a process that slowly shuts off star formation and transforms star-forming galaxies to quiescent galaxies without necessarily changing their structures. On the other hand, there is likely a mechanism that rapidly quenches galaxies, an event that coincides with dramatic structural changes, producing post-starburst galaxies that can be smaller than their progenitors.},
  articleno    = {37},
  author       = {Wu, Po-Feng and van der Wel, Arjen and Bezanson, Rachel and Gallazzi, Anna and Pacifici, Camilla and Straatman, Caroline and Barisic, Ivana and Bell, Eric F and Chauke, Priscilla and van Houdt, Josha and Franx, Marijn and Muzzin, Adam and Sobral, David and Wild, Vivienne},
  issn         = {0004-637X},
  journal      = {ASTROPHYSICAL JOURNAL},
  keywords     = {POST-STARBURST GALAXIES,STAR-FORMATION HISTORIES,SIMILAR-TO 1,ACTIVE,GALACTIC NUCLEI,DIGITAL SKY SURVEY,SUPERMASSIVE BLACK-HOLES,INITIAL,MASS FUNCTION,GAS DEPLETION TIME,VLT DEEP SURVEY,DISK GALAXIES,galaxies: evolution,galaxies: formation,galaxies: high-redshift,galaxies: stellar content,galaxies: structure},
  language     = {eng},
  number       = {1},
  pages        = {20},
  title        = {Fast and slow paths to quiescence : ages and sizes of 400 quiescent galaxies from the LEGA-C survey},
  url          = {http://dx.doi.org/10.3847/1538-4357/aae822},
  volume       = {868},
  year         = {2018},
}

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