Fermi-LAT detection of a new gamma-ray source associated with the high-redshift FSRQ PKS 2134+004 (OX 057)
ATel #12273; Stefano Ciprini (1. INFN Tor Vergata, Rome; 2. ASI Space Science Data Center, Rome), Sara Buson (University of Wuerzburg) on behalf of the Fermi-LAT collaboration
on 7 Dec 2018; 10:11 UT
Credential Certification: Stefano Ciprini (stefano.ciprini@ssdc.asi.it)
Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Blazar, Quasar
Referred to by ATel #: 12278
The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray activity from a source positionally consistent with the flat-spectrum radio quasar PKS 2134+004 (also known as OX 057 and DA 553) with radio coordinates (J2000) R.A.: 324.160776 deg, Dec.: 0.698392deg, (Johnston 1995, AJ, 110, 880) and with redshift z=1.944603 (Hewett et al., 2010, MNRAS, 405, 2302). This source is not in any published LAT catalog and was not detected by AGILE or EGRET.
Preliminary analysis indicates that PKS 2134+004 was detected with high confidence by the Fermi-LAT in the past ten days (2018-Nov-26 / 2018-Dec-06), at an average flux of (6.3 +/- 0.6) X 10^-7 photons cm^-2 s^-1. On 2018 December 4, the source reached a daily averaged gamma-ray flux (E>100MeV) of (1.5+/-0.2) X 10^-6 photons cm^-2 s^-1 with a single power-law photon index of 2.4+/-0.2 (statistical uncertainty only). PKS 2134+004 continued to be detected on a daily basis on 2018 December 5 and 6 with daily averaged gamma-ray fluxes (E>100 MeV) respectively of (1.3+/-0.2) X 10^-6 photons cm^-2 s^-1 and (1.2+/-0.3) X 10^-6 photons cm^-2 s^-1. The corresponding photon spectral indexes (E>100 MeV) of 2.3+/-0.2 and 2.4+/-0.2 suggest a rather stable spectral state during the current flaring state.
Because this is a new detection of this source, we strongly encourage further multifrequency observations of this object. Since Fermi normally operates in an all-sky scanning mode, regular monitoring of this source will continue. PKS 2134+004 is being added to the "LAT Monitored Sources" and consequently a preliminary estimation of the daily gamma-ray flux observed by Fermi-LAT will be publicly available (http://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/). The Fermi-LAT contact person for this source are S. Ciprini (stefano.ciprini at ssdc.asi.it) and S. Buson (sara.buson at astro.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.
