[vsnet-grb-info 25866] Fermi-LAT Gamma-ray Observations of IceCube-200614A and detection of a new gamma-ray source, Fermi J0202.8+3132

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  27966
SUBJECT: Fermi-LAT Gamma-ray Observations of IceCube-200614A and detection of a new gamma-ray source, Fermi J0202.8+3132
DATE:    20/06/16 14:52:21 GMT
FROM:    Simone Garrappa at DESY  <simone.garrappa at desy.de>

S. Garrappa (DESY-Zeuthen) and S. Buson (Univ. of Wuerzburg) on behalf 
of the Fermi-LAT collaboration:

We report an analysis of observations of the vicinity of the high-energy 
IC200614A neutrino event (GCN 27941) with all-sky survey data from the 
Large Area Telescope (LAT), on board the Fermi Gamma-ray Space 
Telescope. The IceCube event was detected on 2020-06-14 at 12:41:21.41 
UT (T0) with J2000 position RA =33.84 (+4.77 -6.39) deg, Decl. 
=31.61(+2.75 -2.28) deg 90% PSF containment. Five cataloged >100 MeV 
gamma-ray sources (The Fermi-LAT Collaboration 2019, 
arXiv:1902.10045) are located within the 90% IC200614A localization 
error. These are  4FGL J0159.0+3313, 4FGL J0202.4+2943, 4FGL 
J0203.7+3042, 4FGL J0205.2+3212 and 4FGL J0220.2+3246. Based on a 
preliminary analysis of the LAT data over the timescales of 1-day and 
1-month prior to T0, these objects are not significantly detected (> 5 
sigma).

We searched for  intermediate (days to years) timescale emission from a 
new gamma-ray transient source. Preliminary analysis indicates no 
significant (> 5 sigma) new excess emission (> 100 MeV), at the 
IC200614A best-fit position. Assuming a power-law spectrum (photon index 
= 2.0 fixed) for a point source at the IceCube best-fit position, the 
 >100 MeV flux upper limit (95% confidence) is < 8e-10 ph cm^-2 s^-1 for 
~11-years (2008-08-04 / 2020-06-14 UTC), < 9e-9 (< 8e-8) ph cm^-2 s^-1 
for a 1-month (1-day) integration time before T0.

Within the 90% confidence localization of the neutrino, ~2.7 deg offset 
from the best-fit IC200614A position, a >5 sigma excess of gamma rays, 
Fermi J0202.8+3132 was detected in an analysis of the integrated LAT 
data (> 100 MeV) between 2008-08-04 and  2020-06-14. Assuming a 
power-law spectrum, the best-fit localization is (J2000) RA: 
  30.71, Dec: 31.55 (0.16 deg 99% containment, 0.08 deg 
68% containment), with best-fit spectral parameters flux = (5 +/- 3)e-10 
ph cm^-2 s^-1 and index = 1.8 +/- 0.2. In a preliminary analysis of the 
LAT data over one day and one month prior T0, Fermi J0202.8+3132  is not 
significantly detected in the LAT data. A possible counterpart for 
Fermi J0202.8+3132 is the BL Lac candidate object NVSSJ020242+313212 
(D'Abrusco et al. 2019, ApJS 242, 1), located 0.03 deg from the best-fit 
LAT localization.

Two additional ~4 sigma excess of gamma rays are detected within the 90% 
confidence localization of IC200614A in an analysis of the LAT data (> 
100 MeV) between 2008-08-04 and  2020-06-14. One is found at the 
best-fit localisation RA= 32.69, Dec= 30.97 (0.15 deg 99% containment), 
and has best-fit spectral parameters flux = (4 +/- 3)e-10 ph cm^-2 s^-1 
and index = (1.8 +/- 0.2). The second one, at best-fit localisation RA= 
35.91, Dec= 32.01 (0.2 deg 99% containment), has best-fit spectral 
parameters flux = (1.3 +/- 0.7)e-9 ph cm^-2 s^-1 and index = (2.2 +/- 
0.2). These excesses are located ~1.2 deg and ~1.8 deg away from the 
best-fit IC200614A position, respectively. In a preliminary analysis of 
the LAT data over one day and one month prior to T0, they are not 
significantly detected in the LAT data.

All values include the statistical uncertainty only. Since Fermi 
normally operates in an all-sky scanning mode, regular monitoring of 
this source will continue. For these observations the Fermi-LAT contact 
persons are S. Garrappa (simone.garrappa at desy.de <http://desy.de/>) 
and S. Buson (sara.buson at uni-wuerzburg.de 
<http://uni-wuerzburg.de/>). 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.