2020/03/31 by D. L. Coppejans, R. Margutti, G. Terreran +38
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Context (archaeology) #Dwarf galaxy #Ejecta #Galaxy #Gamma-ray burst #Gamma-ray bursts and supernovae #Outflow #Stellar mass #Supernova #astro-ph.HE
paper · pdf · doi:10.3847/2041-8213/ab8cc7
Accepted to ApJL
openalex created_date 2020/04/03 · openalex publication_date 2020/05/01 · arxiv created 2020/05/23 · arxiv updated 2020/06/03 · openalex updated_date 2026/08/06
Abstract We present X-ray and radio observations of the Fast Blue Optical Transient CRTS-CSS161010 J045834−081803 (CSS161010 hereafter) at t = 69–531 days. CSS161010 shows luminous X-ray ( L x ∼ 5 × 10 39 erg s −1 ) and radio ( L ν ∼ 10 29 erg s −1 Hz −1 ) emission. The radio emission peaked at ∼100 days post-transient explosion and rapidly decayed. We interpret these observations in the context of synchrotron emission from an expanding blast wave. CSS161010 launched a mildly relativistic outflow with velocity Γ βc ≥ 0.55 c at ∼100 days. This is faster than the non-relativistic AT 2018cow (Γ βc ∼ 0.1 c ) and closer to ZTF18abvkwla (Γ βc ≥ 0.3 c at 63 days). The inferred initial kinetic energy of CSS161010 ( E k ≳ 10 51 erg) is comparable to that of long gamma-ray bursts, but the ejecta mass that is coupled to the mildly relativistic outflow is significantly larger ( ). This is consistent with the lack of observed γ -rays. The luminous X-rays were produced by a different emission component to the synchrotron radio emission. CSS161010 is located at ∼150 Mpc in a dwarf galaxy with stellar mass M * ∼ 10 7 M ⊙ and specific star formation rate sSFR ∼ 0.3 Gyr −1 . This mass is among the lowest inferred for host galaxies of explosive transients from massive stars. Our observations of CSS161010 are consistent with an engine-driven aspherical explosion from a rare evolutionary path of a H-rich stellar progenitor, but we cannot rule out a stellar tidal disruption event on a centrally located intermediate-mass black hole. Regardless of the physical mechanism, CSS161010 establishes the existence of a new class of rare (rate < 0.4% of the local core-collapse supernova rate) H-rich transients that can launch mildly relativistic outflows.