MAXI Investigation into the Long-term X-Ray Variability from the Very-high-energy γ-Ray Blazar Mrk 421
Abstract
The archetypical very-high-energy γ-ray blazar Mrk 421 was monitored for more than three years with the Gas Slit Camera on board Monitor of All Sky X-ray Image (MAXI), and its long-term X-ray variability was investigated. The MAXI light curve in the 3-10 keV range was transformed into the periodogram in the frequency range f = 1 × 10-8-2 × 10-6 Hz. The artifacts on the periodogram, resulting from data gaps in the observed light curve, were extensively simulated for variations with a power-law-like power spectrum density (PSD). By comparing the observed and simulated periodograms, the PSD index was evaluated as α = 1.60 ± 0.25. This index is smaller than that obtained in the higher-frequency range (f >~ 1 × 10-5 Hz), namely, α = 2.14 ± 0.06 in the 1998 ASCA observation of the object. The MAXI data impose a lower limit on the PSD break at f b = 5 × 10-6 Hz, consistent with the break of f b = 9.5 × 10-6 Hz suggested from the ASCA data. The low-frequency PSD index of Mrk 421 derived with MAXI falls well within the range of typical values among nearby Seyfert galaxies (α = 1-2). The physical implications from these results are briefly discussed.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 2015
- DOI:
- 10.1088/0004-637X/798/1/27
- arXiv:
- arXiv:1410.7771
- Bibcode:
- 2015ApJ...798...27I
- Keywords:
-
- BL Lacertae objects: individual: Mrk 421;
- galaxies: active;
- radiation mechanisms: non-thermal;
- X-rays: galaxies;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 27 pages, 8 figures, accepted for ApJ (V797)