TY - JOUR
T1 - Long-Term Monitoring of Blazar PKS 0208-512
T2 - A Change of γ-Ray Baseline Activity from EGRET to Fermi Era
AU - Ammenadka, Krishna Mohana
AU - Bhattacharya, Debbijoy
AU - Bhattacharyya, Subir
AU - Bhatt, Nilay
AU - Stalin, Chelliah Subramonian
N1 - Funding Information:
The first author (KM) acknowledges TMA Pai Ph. D scholarship program, MAHE. The author(s) acknowledge the financial support of ISRO under AstroSat archival Data utilization program.
Funding Information:
This publication uses the data from the AstroSat mission of the Indian Space Research Organisation (ISRO), archived at the Indian Space Science Data Centre (ISSDC). This work has been performed utilizing the calibration data-bases and auxiliary analysis tools developed, maintained and distributed by AstroSat-SXT team with members from various institutions in India and abroad. This work has made use of public Fermi-LAT data obtained from the Fermi Science Support Center (FSSC), provided by NASA Goddard Space Flight Center. This work has made use of public data from CSS survey. The CSS survey is funded by the National Aeronautics and Space Administration under Grant No. NNG05GF22G issued through the Science Mission Directorate Near-Earth Objects Observations Program. The CRTS survey is supported by the U.S. National Science Foundation under grants AST-0909182 and AST-1313422. This research has made use of the NASA/IPAC Extra-galactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This research has made use of data and/or software provided by the High Energy Astrophysics Science Archive Research Center (HEASARC), which is a service of the Astrophysics Science Division at NASA/GSFC and the High Energy Astrophysics Division of the Smithsonian Astrophysical Observatory. Manipal Centre for Natural Sciences-Centre of Excellence, Manipal Academy of Higher Education (MAHE) is acknowledged for facilities and support.
Publisher Copyright:
© 2022 by the authors.
PY - 2022/10
Y1 - 2022/10
N2 - The blazar PKS 0208-512 was in the lowest (Formula presented.) -ray brightness state during the initial 10 years of observations with the Fermi Gamma-ray Space Telescope (Fermi), which was an order of magnitude lower than its flux state during the EGRET era (1991–2000). The weekly averaged maximum (Formula presented.) -ray flux of this source during the first 10 years of Fermi observation is nearly a factor of 3 lower than the highest flux observed by EGRET in a single epoch. During the period 2018–2020, the source showed a large (Formula presented.) -ray flare, with the average brightness similar to the period 1991–2000. We observed the source with AstroSat, during its low and high activity states, respectively. We carried out broad-band spectral energy distribution (SED) modeling of the source using a one-zone leptonic emission model during its various brightness states. From the SED modeling, we found that there was an inefficient conversion from the bulk energy to the particle energy during the long-term low-activity states as compared to the high flux state during the EGRET era and the later part of Fermi observation.
AB - The blazar PKS 0208-512 was in the lowest (Formula presented.) -ray brightness state during the initial 10 years of observations with the Fermi Gamma-ray Space Telescope (Fermi), which was an order of magnitude lower than its flux state during the EGRET era (1991–2000). The weekly averaged maximum (Formula presented.) -ray flux of this source during the first 10 years of Fermi observation is nearly a factor of 3 lower than the highest flux observed by EGRET in a single epoch. During the period 2018–2020, the source showed a large (Formula presented.) -ray flare, with the average brightness similar to the period 1991–2000. We observed the source with AstroSat, during its low and high activity states, respectively. We carried out broad-band spectral energy distribution (SED) modeling of the source using a one-zone leptonic emission model during its various brightness states. From the SED modeling, we found that there was an inefficient conversion from the bulk energy to the particle energy during the long-term low-activity states as compared to the high flux state during the EGRET era and the later part of Fermi observation.
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U2 - 10.3390/universe8100534
DO - 10.3390/universe8100534
M3 - Article
AN - SCOPUS:85140624179
SN - 2218-1997
VL - 8
JO - Universe
JF - Universe
IS - 10
M1 - 534
ER -