2016/07/06 by K. Geréb, K. Gereb, Barbara Catinella +8
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Bulge #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gamma-ray bursts and supernovae #Physics #RADIUS #Star formation #Surface brightness #astro-ph.GA
paper · pdf · doi:10.1093/mnras/stw1675
Accepted for publication in MNRAS
arxiv created 2016/07/06 · openalex publication_date 2016/07/14 · arxiv updated 2016/08/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present our multiwavelength analysis of a prototype H i-excess galaxy, GASS 3505, selected based on having a large gas content (|M_\rm H \small I = 109.9| M⊙) compared to its little associated star formation activity (∼0.1 M⊙ yr−1) in the GALEX Arecibo SDSS Survey (GASS). Very Large Array observations show that the H i in GASS 3505 is distributed in a regularly rotating, extended (∼50 kpc radius) gas ring. In the SDSS optical image GASS 3505 appears as a bulge-dominated galaxy, however deep optical imaging reveals low surface brightness (≳25 mag arcsec−2) stellar emission around the central bulge. Direct evidence for accretion is detected in form of an extended (∼60 kpc) stellar stream, showing that GASS 3505 has experienced a minor merger in the recent past. We investigate the possibility that the H i ring in GASS 3505 was accreted in such a merger event using N-body and smoothed particle hydrodynamic simulations. The best model that reproduces the general properties (i.e. gas distribution and kinematics, stellar morphology) of the galaxy involves a merger between the central bulge and a gas-rich (M⋆ = 109 M⊙ and |M_\rm H \small I|/M⋆ = 10) disc galaxy. However, small discrepancies in the observed and modelled properties could suggest that other sources of gas have to be involved in the build-up of the gas reservoir. This work is the first step towards a larger program to investigate the physical mechanisms that drive the large scatter in the gas scaling relations of nearby galaxies.