Polar-ring galaxies: the SDSS view on the symbiotic galaxies

Abstract

Polar-ring galaxies are multi-spin systems, showing star formation in a blue late-type component, perpendicular to a red early-type one, revealing how galaxy formation can sometimes occur in successive steps. We perform two-dimensional decomposition in the $g$, $r$, $i$ bandpasses of 50 polar-ring galaxies (PRGs) from the Sloan Digital Sky Survey. Each object was fit with a Sérsic host galaxy and a Sérsic ring. Our general results are: (i) The central (host) galaxies of the PRGs are non-dwarf sub-$L^{\ast }$ galaxies with colors typical for early-type galaxies. (ii) Polar structures in our sample are, on average, fainter and bluer than their host galaxies. (iii) In most galaxies, the stellar mass M${}_{\ast }$ of the polar component is not negligible in comparison with that of the host. (iv) The distributions of the host galaxies on the size -- luminosity and Kormendy diagrams are shifted by $\sim 1^m$ to fainter magnitudes in comparison with E/S0 galaxies. It means that the PRGs hosts are more similar to quenched disks than to ordinary early-type galaxies. (v) All the PRGs in our sample are detected in mid-infrared by WISE, and we derive from the 22$\mu$m luminosity their star formation rate (SFR). Their SFR/M${}_{\ast }$ ratio is larger than for the early-type galaxy sample of Atlas${}^{3D}$, showing that the star forming disk brings a significant contribution to the new stars. Globally, PRGs appear frequently on the green valley in the mass-color diagram, revealing the symbiotic character between a red-sequence host and a blue cloud ring.

8 pages, 11 figures, accepted for publication in MNRAS

References in corpus (4)

• The ATLAS3D Project - XXVIII. Dynamically-driven star formation suppression in early-type galaxies
• A Catalogue of Morphologically Classified Galaxies from the Sloan Digital Sky Survey: North Equatorial Region
• The Formation of Polar Disk Galaxies
• The Kormendy Relation for early-type galaxies. Dependence on the magnitude range

Cited by in corpus (10)

• Metallicity and ionization state of the gas in polar-ring galaxies
• Automatic detection of full ring galaxy candidates in SDSS
• Tidal features and disc thicknesses of edge-on galaxies in the SDSS Stripe 82
• Spatial environment of polar-ring galaxies from the SDSS
• Discovery of the Polar Ring Galaxies with deep learning
• DES J024008.08-551047.5:A new member of the polar ring galaxy family
• COUGS-DESI: A Catalog of Unusual Galaxies with Polar Structures in the DESI Legacy Imaging Surveys
• Connecting the dots: Tracing the evolutionary pathway of Polar Ring Galaxies in the cases of NGC 3718, NGC 2685, and NGC 4262
• UGC 10043 in Depth: Dissecting the Polar Bulge and Subtle LSB Features
• A catalog of automatically detected ring galaxy candidates in PanSTARRS