Astrophys. J., 875, 155-155 (2019/April-3)
Revisiting the size-luminosity relation in the era of ultra diffuse galaxies.
DANIELI S. and VAN DOKKUM P.
Abstract (from CDS):
Galaxies are generally found to follow a relation between their size and luminosity, such that luminous galaxies typically have large sizes. The recent identification of a significant population of galaxies with large sizes but low luminosities ("ultra diffuse galaxies," or UDGs) raises the question of whether the inverse is also true-that is, whether large galaxies typically have high luminosities. Here we address this question by studying a size-limited sample of galaxies in the Coma cluster. We select red cluster galaxies with sizes of reff > 2 kpc down to Mg ∼ -13 mag in an area of 9 deg2, using carefully filtered Canada-France-Hawaii Telescope images. The sample is complete to a central surface brightness of µg,0 ≃ 25.0 mag arcsec–2 and includes 90% of Dragonfly-discovered UDGs brighter than this limit. Unexpectedly, we find that red, large galaxies have a fairly uniform distribution in the size-luminosity plane: there is no peak at the absolute magnitude implied by the canonical size-luminosity relation. The number of galaxies within ±0.5 mag of the canonical peak (Mg = -19.69 for 2 < reff < 3 kpc) is a factor of ∼9 smaller than the number of fainter galaxies with -19 < Mg < -13. Large, faint galaxies, such as UDGs, are far more common than large galaxies that are on the size-luminosity relation. An implication is that, for large galaxies, size is not an indicator of the halo mass. Finally, we show that the structure of faint large galaxies is different from that of bright large galaxies: at a fixed large size, the Sersic index decreases with the magnitude following the relation log10n~-0.067Mg-0.989.
© 2019. The American Astronomical Society. All rights reserved.
galaxies: clusters: individual: Coma - galaxies: halos - galaxies: luminosity function, mass function - galaxies: structure
View the reference in ADS
To bookmark this query, right click on this link: simbad:2019ApJ...875..155D and select 'bookmark this link' or equivalent in the popup menu