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NuSTAR Observation of SN2017eaw

ATel #10427; Brian Grefensetette (Caltech), Fiona Harrison (Caltech), Murray Brightman (Caltech)
on 25 May 2017; 17:42 UT
Credential Certification: Brian Grefenstette (Bwgref@srl.caltech.edu)

Subjects: X-ray, Supernovae

Following the detection of the young Type IIp supernova SN2017eaw in NGC 6946 (ATELs #10374, #10376, #10377) and the subsequent detection of soft X-ray flux by Swift (ATEL #10380), we executed a NuSTAR DDT observation of the supernova from 2017-05-21T15:26:09 to 2017-05-22T23:36:09 corresponding to 66.5 ks of on-target time per NuSTAR telescope. We clearly detect a point source at the location of SN2017eaw. Spectroscopic analysis indicates a hard spectrum, with a detection up to 30 keV. The NuSTAR spectrum can be equivalently fit with a hot thermal plasma (apec) model with an electron temperature on the order of 15 keV or a power law with gamma fixed at 2 (to compare with ATEL #10380). For spectroscopic analysis and interpretation we assume a fixed nH column in the direction of NGC 6946 of 2e21 cm2 and a distance of 5.5 Mpc. For the apec (power law) model we can extrapolate the NuSTAR fits to low energy and find an unabsorbed 0.3 to 10 keV flux of 3 (5) x 1e-13 ergs / cm2 / sec, corresponding to an X-ray luminosity of 1.1 (1.8) x 1e39 ergs / sec. Covering the whole of the 0.3 to 30 keV X-ray band over which the source is detected, we find a flux of 4.4e-13 (5.2e-13) ergs / cm2 / sec, corresponding to a luminosity of 1.6 (1.9) x 1e39 ergs / sec. We also detect a line from ionized Fe around 6.65 keV, implying the presence of shock-heated ejecta. We thanks the NuSTAR operations team for their quick response to this DDT request and encourage continued monitoring of this supernova.