Distinguishing RBL-like Objects and XBL-Like Objects With thePeak Emission Frequency of the Overall Energy Spectrum |
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| Authors: | Yi-Ping Qin GZ Xie Xue-Tang Zheng |
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| Institution: | (1) Yunnan Observatory, Chinese Academy of Sciences, Kunming, Yunnan, 650011, P. R. China;(2) Department of Geophysics, Peking University, Chinese Academy of Science-Peking University joint BeijingAstrophysical Center, Beijing, 100871, P. R. China;(3) Department of Physics, YunnanUniversity, Yunnan Astrophysics Center, Kunming, Yunnan, 650091, P. R. China;(4) Department of Physics, Nanjing University of Science andTechnology, Nanjing, Jiangsu, 210014, P. R. China |
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| Abstract: | We investigate quantitatively how the peak emission frequency of the overall energy spectrum is at work in distinguishing
RBL-like and XBL-like objects. We employ the sample of Giommi et al. (1995) to study the distribution of BL Lacertae objects with various locations of the cutoff of the overall energy spectrum.
We find that the sources with the cutoff located at lower frequency are indeed sited in the RBL region of the αro-αoxplane, while those with the cutoff located at higher frequency are distributed in the XBL region. For a more quantitative
study, we employ the BL Lacerta esamples presented by Sambruna et al. (1996), where the peak emission frequency, νp, of each source is estimated by fitting the data with a parabolic function. In the plot of αrx -log νp we find that, in the four different regions divided by the αrx = 0.75 line and thelogνp = 14.7 line, all the RBL-like objects are inside the upper left region, while most XBL-like objects are within the lower
right region. A few sources are located in the lower left region. No sources are in the upper right region. This result is
rather quantitative. It provides an evidence supporting what Giommi et al. (1995) suggested: RBL-like and XBL-like objects can be distinguished by the difference of the peak emission frequency of
the overall energy spectrum.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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