Fermi LAT detection of increasing gamma-ray activity from NGC 1275 and B3 0908+416B
ATel #8219; G. Pivato (INFN and University of Pisa), S. Buson (NASA-GSFC/CRESST/UMBC) on behalf of the Fermi Large Area Telescope Collaboration
on 28 Oct 2015; 02:28 UT
Credential Certification: Sara Buson (sara.buson@nasa.gov)
Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Blazar, Quasar
The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray flux from sources positionally consistent with the flat spectrum radio quasar B3 0908+416B (also known as 3FGL J0912.2+4126, Acero et al. 2015 ApJS, 218, 23) and the radio galaxy NGC 1275 (also known as Perseus A and 3FGL J0319.8+4130).
B3 0908+416B (also known as TXS 0908+416 and 3FGL J0912.2+4126) has radio coordinates RA= 09h12m11.6142s, Dec= +41d26m09.356s (J2000, Petrov and Taylor, 2011 AJ, 142, 89) and is a Compton-dominated blazar at redshift z = 2.563 (Linford et al., 2011, ApJ, 726, 16). Preliminary analysis indicates that it was significantly detected in gamma rays during the past week displaying a weekly flux (E > 100 MeV) of (2.5+/-0.2) x10^-7 ph cm^-2 s^-1 and photon index= 2.0+/-0.1. It was also significantly detected on a daily scale on October 25--26, with daily average fluxes of (0.5+/-0.1) x10^-6 ph cm^-2 s^-1, about a factor of 50 greater than the average flux reported in the third Fermi LAT catalog.
NGC 1275 (also known as Perseus A, 3C 84 and 3FGL J0319.8+4130) has radio coordinates RA= 03h19m48.1601s, Dec= +41d30m42.106s (J2000, Beasley et al. 2002, ApJS, 141, 13) and redshift z=0.017559+/-0.000037 (Strauss et al. 1992, ApJS, 83, 29). Preliminary analysis indicates that it has brightened in gamma rays, reaching a daily peak flux of (1.6+/-0.2) x10^-6 ph cm^-2 s^-1 on 2015 October 25. This flare appears to be part of an extended rising active state that started about the beginning of October 2015 (see GCN/Fermi Notice #1445179916). This is the third time that Fermi is announcing enhanced gamma-ray activity from NGC 1275 (after July 2010, ATel#2737 , and January 2013, ATel#4753). Preliminary estimates of the daily and weekly gamma-ray fluxes observed by Fermi LAT are publicly available (http://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/).
Since Fermi operates in an all-sky scanning mode, regular monitoring of these sources will continue. In consideration of the ongoing activity we strongly encourage multiwavelength observations of these sources. The Fermi LAT contact persons for NGC 1275 are J. Kataoka (kataoka.jun at waseda.jp) and C.C. Cheung (teddy.cheung at nrl.navy.mil), for B3 0908+416B Sara Buson (sara.buson at nasa.gov) and Giovanna Pivato (giovanna.pivato at pi.infn.it).
The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.