No velocity-kicks are required to explain large-distance offsets of Ca-rich supernovae and short-GRBs
Abstract
Environments of supernovae (SNe) and gamma-ray bursts (GRBs) link their progenitors to the underlying stellar population, providing critical clues for their origins. However, various transients including Ca-rich SNe and short-GRBs, appear to be located at remote locations, far from the stellar population of their host galaxy, challenging our understanding of their origin and/or physical evolution. These findings instigated models suggesting that either large velocity-kicks were imparted to the transient progenitors, allowing them to propagate to large distances and attain their remote locations; or that they formed in dense globular-clusters residing in the haloes. Here we show that instead, large spatial-offsets of such transients are naturally explained by observations of highly extended stellar populations in (mostly early-type) galaxy haloes, typically missed since they can only be identified through ultra-deep/stacked images. Consequently, no large velocity kicks, nor halo globular-cluster environments are required in order to explain the origin of these transients. These findings support thermonuclear explosions on white-dwarfs, for the origins of Ca-rich SNe progenitors, and the existence of small (or zero) kick-velocities given to short-GRB progenitors. Furthermore, since stacked/ultra-deep imaging show that early-type galaxies are more extended than late-type galaxies, studies of transients' offset-distribution (e.g. type Ia SNe or FRBs) should account for host galaxy-type. Since early-type galaxies contain older stellar populations, transient arising from older stellar populations would have larger fractions of early-type hosts, and consequently larger fractions of large-offset transients. In agreement with our results for short-GRBs and Ca-rich SNe showing different offset distributions in early versus late-type galaxies.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- June 2021
- DOI:
- 10.1093/mnras/stab794
- arXiv:
- arXiv:2101.11622
- Bibcode:
- 2021MNRAS.503.5997P
- Keywords:
-
- gamma-ray burst: general;
- stars: neutron;
- fast radio bursts;
- gamma-ray bursts;
- neutron star mergers;
- transients: supernovae;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- Comments are welcome