LIGHTS. Survey Overview and a Search for Low Surface Brightness Satellite Galaxies

We present an overview of the LBT Imaging of Galactic Halos and Tidal Structures survey, which currently includes 25 nearby galaxies that are on average ∼1 mag fainter than the Milky Way, and a catalog of 54 low central surface brightness (24 1.5 kpc). This incidence rate falls within expectations of the extrapolation of the published relationship between the number of ultra-diffuse satellite galaxies and host halo mass. Last, we visually identify 12 candidate satellites that host a nuclear star cluster (NSC). The NSC occupation fraction for the sample (12/54) matches that published for satellites of early-type galaxies, suggesting that the parent’s morphological type plays at most a limited role in determining the NSC occupation fraction

Galaxy Sizes Since z=2 from the Perspective of Stellar Mass Distribution within Galaxies

How stellar mass assembles within galaxies is still an open question. We present measurements of the stellar mass distribution on kiloparsec-scales for similar to 5500 galaxies with stellar masses above log(M*/M-circle dot) >= 9.8 up to redshift 2.0. We create stellar mass maps from Hubble Space Telescope observations by means of the pixel-by-pixel spectral energy distribution fitting method. These maps are used to derive radii encompassing 20%, 50%, and 80% (r(20), r(50), and r(80)) of the total stellar mass from the best-fit Sersic models. The reliability and limitations of the structural parameter measurements are checked extensively using a large sample (similar to 3000) of simulated galaxies. The size-mass relations and redshift evolution of r(20), r(50), and r(80) are explored for star-forming and quiescent galaxies. At fixed mass, the star-forming galaxies do not show significant changes in their r(20), r(50), and r(80) sizes, indicating self-similar growth. Only above the pivot stellar mass of log(M*/M-circle dot) similar or equal to 10.5 does r(80) evolve as r(80) proportional to (1 + z)(-0.85 +/- 0.20), indicating that mass builds up in the outskirts of these systems (inside-out growth). The Sersic values also increase for the massive star-forming galaxies toward late cosmic time. Massive quiescent galaxies show stronger size evolution at all radii, in particular, the r(20) sizes. For these massive galaxies, Sersic values remain almost constant since at least z similar to 1.3, indicating that the strong size evolution is related to the changes in the outer parts of these galaxies. We make all the structural parameters publicly available

Self-similar Buildup and Inside-out Growth: Tracing the Evolution of Intermediate-to-high-mass Star-forming Galaxies since z = 2

Abstract We aim to discern scenarios of structural evolution of intermediate-to-high-mass star-forming galaxies (SFGs) since cosmic noon by comparing their stellar mass profiles with present-day stellar masses of log ( M * , 0 / M ⊙ ) = 10.3 − 11 . We addressed discrepancies in the size evolution rates of SFGs, which may be caused by variations in sample selection and methods for size measurements. To check these factors, we traced the evolution of individual galaxies by identifying their progenitors using stellar mass growth histories (SMGHs), integrating along the star-forming main sequence and from the IllustrisTNG simulations. Comparison between the structural parameters estimated from the mass- and light-based profiles shows that mass-weighted size evolves at a slower pace compared to light-based ones, highlighting the need to consider the mass-to-light ratio (M/L) gradients. Additionally, we observed mass-dependent growth in stellar mass profiles: massive galaxies ( log ( M * , 0 / M ⊙ ) ≳ 10.8 ) formed central regions at z ≳ 1.5 and grew faster in outer regions, suggesting inside-out growth, while intermediate-mass and less massive SFGs followed a relatively self-similar mass buildup since z ∼ 2. Moreover, slopes of observed size evolution conflict with the predictions of TNG50 for samples selected using the same SMGHs across our redshift range. To explore the origin of this deviation, we examined changes in angular momentum (AM) retention fraction using the half-mass size evolution and employing a simple disk formation model. Assuming similar dark matter halo parameters, our calculations indicate that the AM inferred from observations halved in the past 10 Gyr while it remained relatively constant in TNG50. This higher AM in simulations may be due to the accretion of high-AM gases into disks.</jats:p