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X-ray Intraday Variability of Five TeV Blazars with NuSTAR

Pandey, Ashwani and Gupta, Alok C. and Wiita, Paul J. (2017) X-ray Intraday Variability of Five TeV Blazars with NuSTAR. Astrophysical Journal, 841 (2). Art. No. 123. ISSN 1538-4357. doi:10.3847/1538-4357/aa705e.

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We have examined 40 Nuclear Spectroscopic Telescope Array (NuSTAR) light curves (LCs) of five TeV emitting high synchrotron peaked blazars: 1ES 0229+200, Mrk 421, Mrk 501, 1ES 1959+650, and PKS 2155−304. Four of the blazars showed intraday variability in the NuSTAR energy range of 3–79 keV. Using an autocorrelation function analysis we searched for intraday variability timescales in these LCs and found indications of several between 2.5 and 32.8 ks in eight LCs of Mrk 421, a timescale around 8.0 ks for one LC of Mrk 501, and timescales of 29.6 and 57.4 ks in two LCs of PKS 2155-304. The other two blazars' LCs do not show any evidence for intraday variability timescales shorter than the lengths of those observations; however, the data were both sparser and noisier for them. We found positive correlations with zero lag between soft (3–10 keV) and hard (10–79 keV) bands for most of the LCs, indicating that their emissions originate from the same electron population. We examined spectral variability using a hardness ratio analysis and noticed a general "harder-when-brighter" behavior. The 22 LCs of Mrk 421 observed between 2012 July and 2013 April show that this source was in a quiescent state for an extended period of time and then underwent an unprecedented double-peaked outburst while monitored on a daily basis during 2013 April 10–16. We briefly discuss models capable of explaining these blazar emissions.

Item Type:Article
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URLURL TypeDescription Paper
Pandey, Ashwani0000-0003-3590-4459
Gupta, Alok C.0000-0002-9331-4388
Wiita, Paul J.0000-0002-1029-3746
Additional Information:© 2017 The American Astronomical Society. Received 2016 September 19; revised 2017 April 24; accepted 2017 April 27; published 2017 June 2. A.C.G. is partially supported by the Chinese Academy of Sciences (CAS) President's International Fellowship Initiative (PIFI; grant No. 2016VMB073). P.J.W. is grateful for hospitality at KIPAC, Stanford University, during a sabbatical. This research has made use of data obtained with NuSTAR, the first focusing hard X-ray mission managed by the Jet Propulsion Laboratory (JPL), and funded by the National Aeronautics and Space Administration (NASA). This research has also made use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (Caltech, USA).
Subject Keywords:BL Lacertae objects: general – BL Lacertae objects: individual (1ES 0229+200, Mrk 421, Mrk 501, 1ES 1959+650, PKS 2155−304)
Issue or Number:2
Record Number:CaltechAUTHORS:20170509-092855159
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Official Citation:Ashwani Pandey et al 2017 ApJ 841 123
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:77292
Deposited By: Joy Painter
Deposited On:12 May 2017 22:41
Last Modified:15 Nov 2021 17:29

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