Fermi LAT detection of a possible new extragalactic gamma-ray source, Fermi J0623-3351

ATel #5668; Buson, S. (University & INFN of Padova)
on 16 Dec 2013; 22:28 UT
Credential Certification: Sara Buson (buson@pd.infn.it)

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The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray flux from an unidentified source whose preliminary location is RA = 95.93 deg, Dec. = -33.85 deg (J2000). Preliminary analysis indicates that on December 14, 2013 the source was detected in gamma rays with a daily averaged flux (E>100MeV) of (0.1+/-0.01)10^-6 cm^-2 s^-1 and a particularly hard gamma-ray spectrum with a photon index of 1.9+/-0.1. A preliminary analysis of data from December 9 to 15, 2013 reveals that the gamma-ray source was significantly detected also during past week with a weekly flux (E>100MeV) of (0.1+/-0.01)10^-6 cm^-2 s^-1 and a photon index of 1.5+/-0.1.

No previous known gamma-ray sources are present within the LAT 95% containment radius of 0.1 deg (statistical errors only). In the vicinity of this new gamma-ray detection lie two possible candidate counterparts. The first one is the blazar PMN J0623-3350 (RA=95.9163333 deg, Dec= -33.8373889 deg J2000, Healey et al., 2007 ApJS, 171, 61), located just 0.02 deg away from the gamma-ray source. The second one is the blazar 6dF J0621497-341150 (RA=95.456667 deg, Dec=-34.197167 deg, J2000.0, Piranomonte et al. 2007 A&A, 470, 787) at redshift z=0.529 (Giommi et al., 2005 A&A, 434, 385) and located 0.5 deg away from the gamma-ray source.

We strongly encourage multiwavelength observations. For this source the Fermi LAT contact person is S. Buson (sara.buson@pd.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.