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NICER observations of the new transient SWIFT J005139.2-721704 in the Small Magellanic Cloud
Centre national d'études spatiales1
Texas Tech University2
University of Crete3
Max Planck Institute for Extraterrestrial Physics4
Yale University5
Massachusetts Institute of Technology6
Astrophysics and Atmospheric Physics, National Space Institute, Technical University of Denmark7
National Space Institute, Technical University of Denmark8
U.S. Naval Research Laboratory9
NASA Goddard Space Flight Center10
University of Southampton11
NASA Marshall Space Flight Center12
...and 2 moreReferred to by ATel #: 12222, 12224 Tweet NICER observed the new transient Swift J005139.2-721704 located in the Small Magellanic Cloud (SMC), and discovered on 2018 Nov. 9 (ATel #12209). The source position identified using Swift XRT as RA=00:51:39.2 and DEC=-72:17:03.6 (with an uncertainty of 1.4″, ATel #12209).
We obtained 8.6 ksec of NICER data between 2018 November 14 at 22:11:16 UTC and 2018 November 15 at 15:36:13 UTC. The average NICER count rate is 22.4 c/s (5.4 mCrab) in the 0.5-8 keV range (after background subtraction of ~0.5 c/s in that range). The spectrum can be described by an absorbed blackbody+powerlaw model in 0.5-8.0 keV range, with chi2=1.2 (399 d.o.f.), and with best fit parameters NH = (0.56±0.04) ×1022cm-2, kT = 0.120±0.005 keV and a powerlaw photon index Gamma = 1.07±0.03 (all uncertainties are at the 90% confidence level).
The flux in that energy range is 1.1×10-10erg s-1cm-2, which corresponds to a luminosity (corrected for absorption) of LX ~7×1037erg s-1, assuming a distance of 60 kpc to the SMC. A timing analysis on these initial NICER exposures finds no sign of short period coherent pulsations. However, we find significant variability (~30% fractional amplitude) on a timescale of ~600-650 seconds.
The current NICER snapshots are too short for a definitive conclusion on a periodicity on such timescale, and additional observations are needed to decipher the nature of this variability. We encourage follow-up observations with other facilities. The short-term schedule of additional NICER observations is as follows: Start Time-----------------End Time-------------Exposure (in seconds) 2018-319T22:49:20 2018-319T23:20:20 1860 2018-320T06:32:20 2018-320T07:04:40 1940 2018-320T14:15:20 2018-320T14:48:40 2000 2018-320T15:48:00 2018-320T16:21:20 2000 2018-320T21:58:20 2018-320T22:32:20 2040 2018-320T23:31:00 2018-321T00:05:00 2040 2018-321T07:14:00 2018-321T07:49:00 2100 2018-321T08:46:40 2018-321T09:21:40 2100 2018-321T13:24:20 2018-321T14:00:00 2140 NICER is a 0.2-12 keV X-ray telescope operating on the International Space Station.
The NICER mission and portions of the NICER science team activities are funded by NASA.
| Language: | English |
|---|---|
| Year: | 2018 |
| Types: | Other |
| ORCIDs: | Jaisawal, G. K. |
