No velocity-kicks are required to explain large-distance offsets of Ca-rich supernovae and short-GRBs

Hagai B. Perets, Paz Beniamini

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish
Pages (from-to)5997-6004
Number of pages8
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
StatePublished - 1 Jun 2021

Bibliographical note

Publisher Copyright:
© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.


  • fast radio bursts
  • gamma-ray burst: general
  • gamma-ray bursts
  • neutron star mergers
  • stars: neutron
  • transients: supernovae


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