Investigating the variability of Swift-BAT blazars with NICER

Abstract

We present results of X-ray spectral and time-domain variability analyses of 4 faint, "quiescent" blazars from the Swift-BAT 105-month catalog. We use observations from a recent, 5-month long NICER campaign, as well as archival BAT data. Variations in the 0.3-2 keV flux are detected on minute, $\sim$weekly, and monthly timescales, but we find that the fractional variability $F_{\mathrm{var}}$ on these timescales is $<25\%$ and decreases on longer timescales, implying generally low-amplitude variability across all sources and showing very low variability on monthly timescales ($F_{\mathrm{var}}\lesssim 13\%$), which is at odds with previous studies that show that blazars are highly variable in the X-rays on a wide range of timescales. Moreover, we find that the flux variability on very short timescales appears to be characterized by long periods of relative quiescence accompanied by occasional short bursts, against the relatively time-stationary nature of the variability of most other AGN light curves. Our analysis also shows that the broadband X-ray spectra (0.3-195 keV) of our sources can be described with different power law models. As is the case with most blazars, we find that 2 sources (2MASS J09343014-1721215 and PKS 0312-770) are well-modeled with a simple power law, while the remaining two (1RXS J225146.9-320614 and PKS 2126-15) exhibit curvature in the form of a log-parabolic power law. We also find that, in addition to the continuum, PKS 2126-15 requires significant absorption at the soft X-rays ($\lesssim$1 keV) to fully describe the observed curvature, possibly due to absorption from the intergalactic medium.

Accepted for publication in MNRAS. 11 pages, 7 figures

References in corpus (20)

• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• HI4PI: A full-sky HI survey based on EBHIS and GASS
• Swift BAT Survey of AGN
• Rapid Variability of Blazar 3C 279 during Flaring States in 2013-2014 with Joint Fermi-LAT, NuSTAR, Swift, and Ground-Based Multi-wavelength Observations
• Correlated Multi-Waveband Variability in the Blazar 3C~279 from 1996 to 2007
• Fermi/LAT broad emission line blazars
• The spectrum of the Broad Line Region and the high-energy emission of powerful blazars
• The Enrichment History of Baryons in the Universe
• Multi-wavelength observations of 3C 279 during the extremely bright gamma-ray flare in 2014 March-April
• A new hard X-ray selected sample of extreme high-energy peaked BL Lac objects and their TeV gamma-ray properties
• Low energy cut-offs and hard X-ray spectra in high-z radio-loud quasars: the Suzaku view of RBS315
• TeV variability in blazars: how fast can it be?
• Comprehensive Monitoring of Gamma-ray Bright Blazars. I. Statistical Study of Optical, X-ray, and Gamma-ray Spectral Slopes
• INTEGRAL observations of the blazar Mrk 421 in outburst (Results of a multi-wavelength campaign)
• Swift observations of high-redshift radio-loud quasars
• Particle-acceleration timescales in TeV blazar flares
• Missing cosmic metals revealed by X-ray absorption towards distant sources
• Multiwavelength variability power spectrum analysis of the blazars 3C 279 and PKS 1510-089 on multiple timescales
• Radio and X-ray observations of an exceptional radio flare in the extreme z=4.72 blazar GB B1428+4217
• Probing the physical properties of the intergalactic medium using blazars

Cited by in corpus (1)

• Long-term hard X-ray variability properties of Swift-BAT blazars