Bright X-ray flares from the BL Lac object Mrk 421, detected with MAXI in 2010 January and February

Details Bright X-ray flares from the BL Lac object Mrk 421, detected with MAXI in 2010 January and February Bright X-ray flares from the BL Lac object Mrk 421, detected with MAXI in 2010 January and February

2010-10-05

arxiv.org/abs/1010.1003v1

Astronomy and Astrophysics

Astrophysics

High Energy Astrophysical Phenomena

14 pages, 4 figures, accepted for PASJ (Vol. 62 No. 6)

Scientific paper

Strong X-ray flares from the blazar Mrk 421 were detected in 2010 January and February through the 7 month monitoring with the MAXI GSC. The maximum 2 -- 10 keV flux in the January and February flares was measured as 120 +- 10 mCrab and 164 +- 17 mCrab respectively; the latter is the highest among those reported from the object. A comparison of the MAXI and Swift BAT data suggests a convex X-ray spectrum with an approximated photon index of about 2. This spectrum is consistent with a picture that MAXI is observing near the synchrotron peak frequency. The source exhibited a spectral variation during these flares, slightly different from those in the previous observations, in which the positive correlation between the flux and hardness was widely reported. By equating the halving decay timescale in the January flare, $t_{\rm d} \sim 2.5 \times 10^{4}$ s, to the synchrotron cooling time, the magnetic field was evaluated as B = 0.045 G $(\delta/10)^{-1/3}$, where $\delta$ is the jet beaming factor. Assuming that the light crossing time of the emission region is shorter than the doubling rise time, $t_{\rm r} \lesssim 2 \times 10^{4}$ s, the region size was roughly estimated as $ R < 6 \times 10^{15}$ cm $(\delta/10)$. These are consistent with the values previously reported. For the February flare, the rise time, $t_{\rm r} < 1.3 \times 10^{5}$ s, gives a loose upper limit on the size as $ R < 4 \times 10^{16}$ cm $(\delta/10)$, although the longer decay time $t_{\rm d} \sim 1.4 \times 10^{5}$ s, indicates B = 0.015 G $(\delta/10)^{-1/3}$, which is weaker than the previous results. This could be reconciled by invoking a scenario that this flare is a superposition of unresolved events with a shorter timescale.

Affiliated with

Also associated with

No associations

Rating

Bright X-ray flares from the BL Lac object Mrk 421, detected with MAXI in 2010 January and February does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Bright X-ray flares from the BL Lac object Mrk 421, detected with MAXI in 2010 January and February, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Bright X-ray flares from the BL Lac object Mrk 421, detected with MAXI in 2010 January and February will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-426678