Fermi LAT detection of a GeV gamma-ray flare from the BL Lac object PKS 1440-389
ATel #15635; Stefano Ciprini (INFN Roma Tor Vergata, & ASI Space Science Data Center, Roma, Italy), C. C. Cheung (Naval Research Laboratory, Washington D. C., USA), on behalf of the the Fermi Large Area Telescope Collaboration.
on 27 Sep 2022; 18:32 UT
Credential Certification: Stefano Ciprini (stefano.ciprini@ssdc.asi.it)
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 gamma-ray flaring activity from a source positionally consistent with the high-energy peaked BL Lac object PKS 1440-389, also known as 4FGL J1443.9-3908 and 3FHL J1443.9-3908 (Abdollahi, et al. 2020, ApJS, 247, 33; Ajello et al. 2017, ApJS, 232, 18), with radio coordinates R.A. = 220.98833 deg, Decl. = -39.14436 deg (J2000; Healey et al. 2007, ApJS, 171, 61), and redshift z=0.1385 (Goldoni et al. 2021, A&A 650, A106).
Preliminary analysis indicates that PKS 1440-389 was in an elevated gamma-ray emission state during the past days, reaching daily averaged gamma-ray fluxes (E>100MeV) of (6.2+/-1.6) X 10^-7 photons cm^-2 s^-1 and (4.6+/-1.8) X 10^-7 photons cm^-2 s^-1 (statistical uncertainty only) respectively on September 24 and 25, 2022. These correspond to a flux increase of a factor of up to about 30 with respect to the average flux reported in the fourth Fermi-LAT catalog (4FGL). The corresponding photon indices are 1.8+/-0.2 and 2.1+/-0.3, where the 4FGL value is 1.82+/-0.02.
This is the first time that the Fermi LAT Collaboration has reported enhanced gamma-ray activity from PKS 1440-389. Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of PKS 1440-389 will continue. This source has also an entry in the FSSC light curve repository (https://fermi.gsfc.nasa.gov/ssc/data/access/lat/LightCurveRepository/source.php?source_name=4FGL_J1443.9-3908). We encourage multifrequency observations of this gamma-ray source. For this source, the Fermi-LAT contact persons are S. Ciprini (stefano.ciprini[at]ssdc.asi.it) and C.C. Cheung (teddy.cheung[at]nrl.navy.mil).
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.
