NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-25 T13:09:25 PDT
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For refcode 2006A&A...456..131P:
Retrieve 17 NED objects in this reference.
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Copyright by European Southern Observatory (ESO). Reproduced by permission
2006A&A...456..131P Filling the infrared gap: ISO observations of 1 Jy BL Lacertae objects P. Padovani, P. Giommi, P. Abraham, S. Csizmadia and A. Moor Received 7 April 2006 / Accepted 8 June 2006 Abstract. Aims.The large majority of BL Lacertae objects belonging to the 1 Jy sample, the class prototype for radio-selected sources, are thought to emit most of their synchrotron power in the far infrared band. Ironically, this spectral region is very sparsely sampled, with only a minority of the objects having IRAS data (most of them being upper limits or low-quality detections). We aim at filling this infrared gap by presenting new, simultaneous ISOCAM and ISOPHOT observations over the 7-200 microns range (observer's frame) for half the sample. A precise measurement of the position of the synchrotron peak frequency, {nu}_peak_, can provide direct information about particle acceleration mechanisms and constrain the inverse Compton radiation that will be detected by up-coming new {gamma}-ray missions. Methods.We have observed seventeen 1 Jy BL Lacertae objects with the camera and the photometer on board the Infrared Space Observatory (ISO) satellite. Given the intrinsic variability of these sources, the data were taken by concatenating the pointings to ensure simultaneity. The ISOPHOT data reduction was done employing a novel correction, which mitigates the effect of chopping for faint sources. Results.Using our new ISO data, complemented by nearly-simultaneous radio and optical observations for ten and four objects respectively, and other multi-frequency data, we have built the spectral energy distributions of our sources (plus a previously published one) and derived the rest-frame {nu}_peak_. Its distribution is centred at ~10^13^ Hz (~30 microns) and is very narrow, with ~60% of the BL Lacs in the 1-3 x 10^13^ Hz range. Given our set of simultaneous infrared data, these represent the best determinations available of the synchrotron peak frequencies for low-energy peaked BL Lacs. A comparison with previous such estimates, based on non-simultaneous optical and near infrared data, may indicate strong {nu}_peak_ variations in a number of sources, possibly associated with large flares as observed in the high-energy peaked BL Lac MKN 501. Key words: galaxies: BL Lacertae objects: general, infrared: galaxies, methods: data, analysis, radiation mechanisms: non-thermal
Retrieve 17 NED objects in this reference.
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