Galaxy Evolution in Local Group Analogs. I. A GALEX study of nearby groups

Abstract

Understanding the astrophysical processes acting within galaxy groups and their effects on the evolution of the galaxy population is one of the crucial topic of modern cosmology, as almost 60% of galaxies in the Local Universe are found in groups. We imaged in the far (FUV 1539 A) and near ultraviolet (NUV 2316 A) with GALEX three nearby groups, namely LGG93, LGG127 and LGG225. We obtained the UV galaxy surface photometry and, for LGG225, the only group covered by the SDSS, the photometry in u, g, r, i, z bands. We discuss galaxy morphologies looking for interaction signatures and we analyze the SED of galaxies to infer their luminosity-weighted ages. The UV and optical photometry was also used to perform a kinematical and dynamical analysis of each group and to evaluate the stellar mass. A few member galaxies in LGG225 show a distorted UV morphology due to ongoing interactions. (FUV-NUV) colors suggest that spirals in LGG93 and LGG225 host stellar populations in their outskirts younger than that of M31 and M33 in the LG or with less extinction. The irregular interacting galaxy NGC3447A has a significantly younger stellar population (few Myr old) than the average of the other irregular galaxies in LGG225 suggesting that the encounter triggered star formation. The early-type members of LGG225, NGC3457 and NGC3522, have masses of the order of a few 10^9 Mo, comparable to the Local Group ellipticals. For the most massive spiral in LGG225, we estimate a stellar mass of ~4x10${}^{10}$ Mo, comparable to M33 in the LG. Ages of stellar populations range from a few to ~7 Gyr for the galaxies in LGG225. The kinematical and dynamical analysis indicates that LGG127 and LGG225 are in a pre-virial collapse phase, i.e. still undergoing dynamical relaxation, while LGG93 is likely virialized. (Abridged)

20 pages, 13 figures, accepted for publication in Astronomy and Astrophysics

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Cited by in corpus (20)

• The Ultraviolet Sky: An Overview from the GALEX Surveys
• The Galaxy Evolution Explorer (GALEX). Its legacy of UV surveys, and science highlights
• Tracing rejuvenation events in nearby S0 galaxies
• The ($NUV-r$) vs. $M_r$ as a tracer of early-type galaxies evolution in USGC U376 and LGG 225 groups
• Early-phase photometry and spectroscopy of transitional Type Ia SN 2012ht: Direct constraint on the rise time
• Galaxy evolution in nearby groups. II. Galaxy evolution in nearby loose groups. II. Photometric and kinematic characterization of USGC U268 and USGC U376 group members in the Leo cloud
• Matched photometric catalogs of GALEX UV sources with Gaia DR2 and SDSS DR14 databases (GUVmatch)
• Hot gas in groups: NGC 5328 and the intriguing case of NGC 4756 with XMM-Newton
• Galaxy evolution in groups. NGC 3447/NGC 3447A: the odd couple in LGG 225
• Galaxy evolution in nearby galaxy groups. III. A GALEX view of NGC 5846, the largest group in the local universe
• The vertical structure of the spiral galaxy NGC 3501: first stages of the formation of a thin metal-rich disc
• NGC 3934: a shell galaxy in a compact galaxy environment
• Dorado and its member galaxies. Ha imaging of the group backbone
• Dorado and its member galaxies. III. Mapping star formation with FUV imaging from UVIT
• A multi-wavelength study of the evolution of Early-Type Galaxies in Groups: the ultraviolet view
• Energetic constraints to chemo-photometric evolution of spiral galaxies
• Galaxy evolution in groups. USGC U268 and USGC U376 in the Leo cloud
• Dorado and its member galaxies II. A UVIT picture of the NGC 1533 substructure
• Extraplanar emission in isolated edge-on late-type galaxies. I. The H$\alpha$ distribution versus to the old and young stellar discs
• High reddening patches in Gaia DR2. Possible artifacts or indication of star formation at the edge of the Galactic disk