TY - JOUR
T1 - Rapid synchrotron flares from BL Lacertae detected by ASCA and RXTE
AU - Tanihata, Chiharu
AU - Takahashi, Tadayuki
AU - Kataoka, Jun
AU - Madejski, Greg M.
AU - Inoue, Susumu
AU - Kubo, Hidetoshi
AU - Makino, Fumiyoshi
AU - Mattox, John R.
AU - Kawai, Nobuyuki
PY - 2000/11/1
Y1 - 2000/11/1
N2 - We report the variable X-ray emission from BL Lacertae detected in the ASCA ToO observation conducted during the EGRET and RXTE pointings, coincident with the 1997 July outburst. The source showed a historically high state of X-ray, optical, and γ-ray emission, with its 2-10 keV flux peaking at ∼3.3 × 10-11 ergs cm-2 s-1. This is more than 3 times higher than the value measured by ASCA in 1995. We detected two rapid flares that occurred only in the soft X-ray band, while the hard X-ray flux also increased, but decayed with a much longer timescale. Together with the requirement of a very steep and varying power law dominating the soft X-ray band in addition to the hard power law, we suggest that both the high-energy end of the synchrotron spectrum and the hard inverse Compton spectrum were visible in this source during the outburst. We discuss the possible origins of the observed variability timescales, and interpret the short timescales of the soft X-ray variability as reflecting the size of the emission region.
AB - We report the variable X-ray emission from BL Lacertae detected in the ASCA ToO observation conducted during the EGRET and RXTE pointings, coincident with the 1997 July outburst. The source showed a historically high state of X-ray, optical, and γ-ray emission, with its 2-10 keV flux peaking at ∼3.3 × 10-11 ergs cm-2 s-1. This is more than 3 times higher than the value measured by ASCA in 1995. We detected two rapid flares that occurred only in the soft X-ray band, while the hard X-ray flux also increased, but decayed with a much longer timescale. Together with the requirement of a very steep and varying power law dominating the soft X-ray band in addition to the hard power law, we suggest that both the high-energy end of the synchrotron spectrum and the hard inverse Compton spectrum were visible in this source during the outburst. We discuss the possible origins of the observed variability timescales, and interpret the short timescales of the soft X-ray variability as reflecting the size of the emission region.
KW - BL Lacertae objects: individual (BL Lacertae)
KW - Galaxies: active
KW - Radiation mechanisms: nonthermal
KW - X-rays: galaxies
UR - http://www.scopus.com/inward/record.url?scp=0034311597&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0034311597&partnerID=8YFLogxK
U2 - 10.1086/317086
DO - 10.1086/317086
M3 - Article
AN - SCOPUS:0034311597
VL - 543
SP - 124
EP - 130
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1 PART 1
ER -