Structural analysis of star-forming blue early-type galaxies: Merger-driven star formation in elliptical galaxies

Abstract

Star-forming blue early-type galaxies at low redshift can give insight to the stellar mass growth of L$\ast$ elliptical galaxies in the local Universe. We wish to understand the reason for star formation in these otherwise passively evolving red and dead stellar systems. The fuel for star formation can be acquired through recent accretion events such as mergers or flyby. The signatures of such events should be evident from a structural analysis of the galaxy image. We carried out structural analysis on SDSS $r$-band imaging data of 55 star-forming blue elliptical galaxies, derived the structural parameters, analysed the residuals from best-fit to surface brightness distribution, and constructed the galaxy scaling relations. We found that star-forming blue early-type galaxies are bulge-dominated systems with axial ratio $>$ 0.5 and surface brightness profiles fitted by Sersic profiles with index ($n$) mostly $>$ 2. Twenty-three galaxies are found to have $n$ $<$ 2; these could be hosting a disc component. The residual images of the 32 galaxy surface brightness profile fits show structural features indicative of recent interactions. The star-forming blue elliptical galaxies follow the Kormendy relation and show the characteristics of normal elliptical galaxies as far as structural analysis is concerned. There is a general trend for high-luminosity galaxies to display interaction signatures and high star formation rates. The star-forming population of blue early-type galaxies at low redshifts could be normal ellipticals that might have undergone a recent gas-rich minor merger event. The star formation in these galaxies will shut down once the recently acquired fuel is consumed, following which the galaxy will evolve to a normal early-type galaxy.

Accepted for publication in Astronomy & Astrophysics

References in corpus (8)

• Galaxy Zoo: the dependence of morphology and colour on environment
• Neutral hydrogen in nearby elliptical and lenticular galaxies: the continuing formation of early-type galaxies
• A catalogue of 2D photometric decompositions in the SDSS-DR7 spectroscopic main galaxy sample: preferred models and systematics
• The role of minor mergers in the recent star formation history of early-type galaxies
• Tidal debris in elliptical galaxies as tracers of mergers with disks
• Building gas rings and rejuvenating S0 galaxies through minor mergers
• Misalignment between cold gas and stellar components in early-type galaxies
• Early-type galaxies at intermediate redshift observed with HST WFC3: perspectives on recent star-formation

Cited by in corpus (17)

• Galaxy Zoo: major galaxy mergers are not a significant quenching pathway
• Star-forming early- and quiescent late-type galaxies in the local Universe
• The morphological transformation and the quenching of galaxies
• Galaxy And Mass Assembly (GAMA): Blue spheroids within 87 Mpc
• NGC 741 - Mergers and AGN feedback on galaxy group scale
• The galaxy mass-size relation in CARLA clusters and proto-clusters at 1.4 < z < 2.8: larger cluster galaxy sizes
• Age, metallicity and star formation history of spheroidal galaxies in cluster at z~1.2
• Relaxed blue ellipticals: accretion-driven stellar growth is a key evolutionary channel for low mass elliptical galaxies
• Witnessing the star-formation quenching in $L_{\ast }$ ellipticals
• Impact of Galaxy Mergers on the Colours of Cluster Galaxies
• The physical properties of S0 galaxy PGC 26218: the origin of starburst and star formation
• Decoding NGC 7252 as a blue elliptical galaxy
• Deep optical imaging of star-forming blue early-type galaxies: Color map structures and faint features indicative of recent mergers
• Structure and Kinematics of Star-forming Elliptical Galaxies in SDSS-MaNGA
• An Imaging and Spectroscopic Exploration of the Dusty Compact Obscured Nucleus Galaxy Zw~049.057
• Euclid Quick Data Release (Q1): The evolution of the passive-density and morphology-density relations between $z=0.25$ and $z=1$
• Star-forming S0 Galaxies in SDSS-MaNGA: fading spirals or rejuvenated S0s?