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Early gamma--ray emission from SN2014J during the optical maximum as obtained by INTEGRAL

ATel #6099; J. Isern (ICE-CSIC/IEEC), J. Knoedlseder (IRAP), P. Jean (IRAP), F. Lebrun (APC-CNRS), M. Renaud (LUPM), E. Bravo (DFEN-UPC), E. Churazov (IKI, MPA), S. Grebenev (IKI), R. Sunyaev (IKI, MPA), S. Soldi (APC), A. Domingo (CAB-CSIC/INTA), E. Kuulkers (ESAC/ESA), P. Hoeflich (U. FLorida), N. Elias-Rosa (INAF, Obs. Astronomico Padova), D. H. Hartmann (Clemson U.), M. Hernanz (ICE-CSIC/IEEC), C. Badenes (U. Pittsburgh), I. Dominguez (DFMC-UGR), D. Garcia-Senz (DFEN-UPC), C. Jordi (ICC-UB/IEEC), G. Lichti (MPE), G. Vedrenne (IRAP), P. Von Ballmoos (IRAP)
on 25 Apr 2014; 17:22 UT
Credential Certification: Jordi Isern (isern@ice.cat)

Subjects: Gamma Ray, Supernovae

SN2014J is a supernova discovered in M82 by Fossey et al. (IAU Central Bureau Telegrams, 3792, 1, 2014) on January 21th 2014 and classified as a SNIa by Cao et al. (ATel # 5786, 2014). The date of the explosion was estimated to be 2014 Jan 14.72 (Zheng et al., arXiv: 1401.7968) and the optical maximum was estimated to have occurred around January 31st.

The source was observed with all the instruments of INTEGRAL (SPI, IBIS/ISGRI, JEM-X and OMC; see also ATels #5835, #5992). The observations with INTEGRAL started according to the following schedule: revolution 1380, starting at 22:36:22 of 2014-01-31 and covering the period of 16.5-19.2 days after the explosion, and revolutions 1381 to 1386 starting at 06:55:23 of 2014-01-31 and covering the period 19.6-35.2 days after the explosion.

Our analysis of the IBIS/ISGRI data shows an excess of emission at the position of SN2014J in the 70-190 keV band that corresponds to a mean flux of (2.2±0.4) x 10-4 cm-2s-1 during the revolutions 1380-1386. Nothing is visible at the SN2014J position in the 25-70 keV band. The flux detected by ISGRI in the 147-168 band during revolution 1380 was (1.3±0.5) x 10-4 cm-2s-1. Our analysis of the SPI data shows at the position of SN2014J a broadened, FWHM =5.3±3.6 (stat)±0.3(sys) keV, and redshifted gamma-ray line centered at 155.0±1.6 (stat)±0.3 (sys) keV with a flux of (2.4±1.5 (stat)±0.1 (sys)) x 10-4cm-2s-1. The line is detected at a significance of 3.5σ. The average flux during orbits 1380-1385 amounted to (1.8±1.0 (stat)±0.1 (sys)) x 10-4 cm-2 s-1, with a line center at 155.4±1.6 (stat)±0.3 (sys) keV and a FWHM of 6.3±3.8 (stat)±0.3 (sys) keV. The line is detected at a significance of 4 σ. This analysis of SPI data has also revealed an emission excess in the 650-1300 keV band during the revolutions 1380-1385 that corresponds to a flux of (1.2±0.4 (stat)±0.1 (sys)) x10-3 cm-2s-1 with a significance of ~3σ.

The detection of the 847 keV gamma-ray line of radio-active Co56 from SN2014J in a later phase was reported by the INTEGRAL team in ATel #5992

JEM-X has detected a source consistent with the position of SN2014J and M82X-1, an ULX source located 0.8 arc min from the supernova. The flux in the 3-10 keV band was ~1.5 x10-3 cm-2s-1 consistent with the level of emission obtained by JEM-X at the position of M82X-1 before 2014. No source was detected in the 10-25 keV band, with a 3σ flux upper limit of 6x10-4 cm-2s-1.

The light curve obtained with the optical monitor OMC in the V-band was corrected with the background previously obtained by this camera before the explosion. The maximum, MV (max) ~10.6, without correcting for extinction, occurred at JD 2456692±1 (February 3d, 2014) and Δm15(V) ~ 0.6.