X-ray Intraday Variability of HBL Blazars with XMM-Newton

TL;DR

This study investigates the X-ray intraday variability of ten TeV-emitting HBL blazars using XMM-Newton data, finding limited variability and no significant spectral changes, while analyzing their emission properties and underlying mechanisms.

Contribution

It provides the first comprehensive analysis of intraday X-ray variability in a sample of ten TeV HBL blazars with detailed spectral and temporal characterization.

Findings

Most blazars showed some intraday variability at 3-sigma levels.

No significant hardness ratio variations were observed.

Power spectral density slopes ranged from 1.11 to 2.93.

Abstract

We present an extensive study on the X-ray intraday variability of ten TeV-emitting high synchrotron peaked blazars (HBLs): 1ES 0229+200, 1ES 0414+009, PKS 0548-322, 1ES 1101-232, 1H 1219+301, H 1426+428, Mrk 501, 1ES 1959+650, PKS 2005-489, and 1ES 2344+514 made with twenty-five XMM-Newton pointed observations during its operational period. Intraday variability has been estimated in three energy bands: soft (0.3--2 keV), hard (2--10 keV) and total (0.3--10 keV). Although seven out of these ten TeV HBLs exhibited some intraday variability at three-sigma levels no major variations exceeding six percent were detected. We explored the spectral properties of the sample by extracting the hardness ratio from the soft and hard bands; no significant variations in the hardness ratio were observed in any source. We performed power spectral density analyses on the variable light-curves by fitting power-laws, yielding slopes lying in the range from 1.11 to 2.93 for different HBLs. We briefly discuss possible emission mechanisms and carry out rough estimates for magnetic fields, electron Lorentz factors and emission region sizes for seven of these HBLs.