AstroNote 2020-218

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2020-11-05 23:00:03
Type: Object/s-Data/Analysis
Chandra detection of X-ray emission at the location of FBOT AT2020xnd
Authors: David Matthews (Northwestern), Raffaella Margutti (Northwestern), Daniel Brethauer (Northwestern), Joe Bright (Northwestern), Deanne Coppejans (Northwestern), Kate D. Alexander (Northwestern), Tanmoy Laskar (Bath), Lindsay DeMarchi (Northwestern), Wynn Jacobson-Galan (Northwestern), Giulia Migliori (INAF/IRA), Adriano Baldeschi (Northwestern), Michael C. Stroh (Northwestern), Katie Auchettl (University of Melbourne/UCSC)
We report the detection of significant X-ray emission from the fast blue optical transient AT2020xnd at z=0.2442.

We report observations of the Fast Blue Optical Transient (FBOT) AT2020xnd (ATel #14105, AstroNote #2020-199) with the Chandra X-ray Observatory (CXO). We observed AT2020xnd on November 4th, 2020 (t=21-27 days since explosion) with the ACIS instrument for a total exposure of 20 ks (OBS ID: 23547, Proposal 22500192 PI: D. Matthews).

We detect significant X-ray emission from the location of AT2020xnd, and we infer an absorbed flux of  ~3.5E-14 erg/s/cm^2 (0.3-10 keV) for a power law spectral model with a photon index of 1.3 (+0.5, -0.4) 1 sigma c.l.  The Galactic neutral hydrogen column density along the line of sight of the transient is 5.12E+20 cm^-2 (HEASARC).

At a redshift of z=0.2442 (d~1.24 Gpc) this corresponds to a luminosity of ~6.4E+42 erg/s (0.3-10 keV), which is comparable to the luminosity of AT2018cow at similar times (Margutti+ 2019, Sandoval+ 2019). We emphasize that this makes AT2020xnd the highest-z detection of a FBOT in X-rays, the second FBOT with X-rays detected at such an early epoch, and the third FBOT ever detected in X-rays, alongside AT2018cow and CSS161010 (Coppejans+ 2020). Further observations are planned.

We thank the entire CXO team for carrying out these observations.


Show current TNS values
CatalogNameReported RAReported DECReported Obj-TypeReported RedshiftHost NameHost RedshiftRemarksTNS RATNS DECTNS Obj-TypeTNS Redshift
TNS2020xnd [ZTF20acigmel]22:20:02.030-02:50:25.30SN0.244222:20:02.030-02:50:25.30
TNS2018cow [ZTF18abcfcoo]16:16:00.220+22:16:04.91SN Ic-BL0.014116:16:00.220+22:16:04.91SN Ic-BL