Fermi-LAT detection of a new flaring gamma-ray source Fermi J0146-1351 compatible with a new X-ray source

ATel #15933; Janeth Valverde (UMBC & NASA / GSFC), Denis Bernard (LLR, Ecole Polytechnique & CNRS / IN2P3), Daniel Kocevski (NASA / MSFC), C. C. Cheung (NRL), on behalf of the Fermi Large Area Telescope Collaboration.
on 7 Mar 2023; 00:51 UT
Credential Certification: Janeth Valverde (valverde@llr.in2p3.fr)

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The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed gamma-ray activity from a position where no gamma-ray emitting source was previously known, at a significance greater than 8 sigma, and centered on the coordinates (J2000) R.A. = 26.51 deg, Decl. = -13.86 deg, with 68% and 95% containment radii of 0.11 deg and 0.18 deg, respectively. Preliminary analysis indicates that this source was in an elevated gamma-ray emission state during the week 2023 February 6 - 13, with an averaged gamma-ray flux (E>100MeV) of (1.2+/-0.3) X 10^-7 photons cm^-2 s^-1 (statistical uncertainty only). The corresponding photon index is 2.2+/-0.2. A search of Fermi LAT data over the full month of February with a daily cadence showed a significant signal for 3 successive days only, February 9 - 11.

A Swift Target of Opportunity led to a 3.6 ks observation with the Swift X-ray Telescope (XRT), which took place on 2023 February 26 and resulted in the detection of an X ray-source centered on the coordinates R.A. = 26.3910 deg, Decl. = -13.8834 deg, with an uncertainty radius of 4.7 arcsec (90% confidence). This position is consistent with the radio source NVSS J014533-135258 (WISEA J014533.69-135259.2). Preliminary analysis indicates an averaged observed X-ray flux (0.3-10 keV) of 3.7 (+1.7, -1.6)×10^-13 erg cm^-2 s^-1 and a photon index of 1.6 (+0.9, -0.5).

Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. We encourage multifrequency observations of this source. For this source, the Fermi-LAT contact person is Janeth Valverde (janeth@umbc.edu).

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.

We acknowledge the use of public data from the Swift data archive, and thank the team for their support of our request.