منابع مشابه
Intermediate Scale Structures in BL Lac objects
Abstract. The parsec-scale total intensity structures of BL Lac objects share many characteristics with quasars: e.g. well-collimated jets and superluminal motion. However, the jets of BL Lac objects appear to fade much more quickly than those in quasars and on VLA scales many BL Lacs have structures comparable to those of low luminosity (FR I) radio galaxies, in which kpc-scale flow speeds are...
متن کاملBl Lac Objects
SUMMARY: We present the radio detection of 18 BL Lac objects from our survey of over 575 deg 2 of sky. These 18 objects are located within 20 ′′ of the X-ray position, of which 11 have a measured red-shift. All candidates are radio emitters above ∼1 mJy and fall within the range of existing samples on the two colour, α ro vs α ox , diagram with a transitional population of three (3) evident. Tw...
متن کاملTeV candidate BL Lac objects
The TeV emission of low power BL Lac objects has been established by the detection of an handful of them. The knowledge of the level of the TeV emission and its spectrum can shed light on the particle acceleration mechanisms, and it is especially important to assess the still uncertain level of the far infrared background radiation, which can absorb the TeV photons through photon–photon interac...
متن کاملOn the Nature of BL Lac Objects
The BL Lacertae objects, or BL Lacs, have multi-wavelength continua dominated by non-thermal emission from a relativistic jet, and are characterised by a lack of optical emission lines. We find, through observations and modelling that the dominant factor in a source being called a BL Lac is the intrinsic lack of flux from the broad-line region – likely connected with a weak accretion disc – rat...
متن کاملNew Extreme Synchrotron Bl Lac Objects
We report on the BeppoSAX observations of four “extreme” BL Lacs, selected to have high synchrotron peak frequencies. All have been detected also in the PDS band. For 1ES 0120+340, PKS 0548–322 and H 2356–309 the spectrum is well fitted by a convex broken powerlaw, thus locating the synchrotron peak around 1–4 keV. 1ES 1426+428 presents a flat energy spectral index (αx = 0.92) up to ∼100 keV, t...
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ژورنال
عنوان ژورنال: Monthly Notices of the Royal Astronomical Society
سال: 2001
ISSN: 0035-8711,1365-2966
DOI: 10.1046/j.1365-8711.2001.04519.x