2024/01/24 by Rodrigo Flores-Freitas, Flores-Freitas, Rodrigo, Marina Trevisan +9 · 1 citation
Computer Science · Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics of Galaxies (astro-ph.GA) #Data Visualization and Analytics #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena
paper · pdf · doi:10.48550/arxiv.2401.13252
openalex publication_date 2024/01/24 · openalex created_date 2024/01/26 · openalex updated_date 2026/08/01
Compact groups of dwarf galaxies (CGDs) have been observed at low redshifts (z<0.1) and are direct evidence of hierarchical assembly at low masses. To understand the formation of CGDs and the galaxy assembly in the low-mass regime, we search for analogues of compact (radius ≤ 100 kpc) groups of dwarfs (7 ≤ log[M∗/\rm M_\odot] ≤ 9.5) in the IllustrisTNG highest-resolution simulation. Our analysis shows that TNG50-1 can successfully produce CGDs at z=0 with realistic total and stellar masses. We also find that the CGD number density decreases towards the present, especially at z \lesssim 0.26, reaching n ≈ 10-3.5 \rm cMpc-3 at z = 0. This prediction can be tested observationally with upcoming surveys targeting the faint end of the galaxy population and is essential to constrain galaxy evolution models in the dwarf regime. The majority of simulated groups at z ∼ 0 formed recently (\lesssim 1.5 \rm Gyr), and CGDs identified at z ≤ 0.5 commonly take more than 1 Gyr to merge completely, giving origin to low- to intermediate-mass (8 ≤ log[M∗/\rm M_\odot] ≤ 10) normally star-forming galaxies at z=0. We find that halos hosting CGDs at z = 0 formed later when compared to halos of similar mass, having lower stellar masses and higher total gas fractions. The simulations suggest that CGDs observed at z ∼ 0 arise from a late hierarchical assembly in the last ∼ 3 Gyr, producing rapid growth in total mass relative to stellar mass and creating dwarf groups with median halo masses of ∼ 1011.3 \rm M_\odot and B-band mass-to-light ratios mostly in the range 10 \lesssim M/L \lesssim 100, in agreement with previous theoretical and observational studies.