Kinematically detected polar rings/disks in blue compact dwarf galaxies

TL;DR

This study identifies polar gaseous structures in two blue compact dwarf galaxies using ionized gas velocity fields, suggesting external gas accretion or merging as triggers for star formation bursts.

Contribution

First detection of kinematically confirmed polar rings/disks in BCD galaxies using Fabry-Perot interferometry, highlighting their potential prevalence.

Findings

Gas in Mrk 33 is in a compact polar disk.

Mrk 370 has a warped, complex gaseous structure.

Polar structures may be present in up to 10-15% of BCD galaxies.

Abstract

Polar ring galaxies are systems with nearly orthogonally rotated components. We have found the gas on polar (or strongly inclined) orbits in two BCD galaxies using ionized gas velocity fields taken with a Fabry-Perot interferometer of the SAO RAS 6-m telescope. Our analysis shows that all ionized gas in Mrk 33 is concentrated in a compact disk (3 kpc in diameter) which rotates in the polar plane relative to the main stellar body. The gaseous disk in Mrk 370 has a more complex structure with a heavily warped innermost part. The presence of polar gaseous structures supports an idea that current the burst of star formation in these galaxies is due to the external gas accretion or merging. A possible fraction of polar structures among BCD galaxies seems to be very large (up to 10-15%)