2017/05/08 by Ashwani Pandey, A. K. Pandey, Alok C. Gupta +1 · 1 citation
Physics and Astronomy · #Astrophysics #Astrophysics and Cosmic Phenomena #Blazar #Dark Matter and Cosmic Phenomena #Demography #Gamma ray #Physics #Population #Radio Astronomy Observations and Technology #Spectral properties #Synchrotron #astro-ph.HE
paper · pdf · doi:10.3847/1538-4357/aa705e
published as 2017, ApJ, 841, 123 · 21 pages, 4 figures, 4 tables, Accepted for Publication in ApJ
arxiv created 2017/05/08 · openalex publication_date 2017/06/01 · arxiv updated 2017/12/20 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Abstract 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.