Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.sao.ru/cats/~satr/RFSymp/abs/26_Nieppola.ps Äàòà èçìåíåíèÿ: Mon Oct 9 11:14:24 2006 Äàòà èíäåêñèðîâàíèÿ: Tue Oct 2 09:33:55 2012 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: arp 220

SPECTRAL ENERGY DISTRIBUTIONS AND 37 GHz
MONITORING OF BL LACERTAE OBJECTS
E. Nieppola 1 , M. Tornikoski 1 , A. L˜ahteenm˜aki 1 , E. Valtaoja 2
1 Mets˜ahovi Radio Observatory
Mets˜ahovintie 114, 02540 Kylm˜al˜a, Finland
2 Tuorla Observatory
V˜ais˜al˜antie 20, 21500 Piikki˜o, Finland
eni@kurp.hut.fi
BL Lacertae objects (BL Lacs) are a group of active galactic nuclei (AGN) characterized by
strong and rapid variability, strong optical polarization and a lack of prominent emission
lines in their spectra. We have determined spectral energy distributions (SED) for over 300
of these objects using archival multi­frequency data and fitted a parabolic function to the
synchrotron component of the SED (Nieppola et al. 2006). The peak frequencies of the
synchrotron components range between log # peak = 12.67--21.46. We divided the sample into
low­energy (LBLs), intermediate energy (IBLs) and high­energy (HBLs) BL Lacs according
to their log # peak . The correlation between log # peak and the luminosity at # peak was not
significant, in contradiction with the ``blazar sequence'' scenario (Fossati et al. 1998). We
also report a summary of the first 3.5 years of observations with the extensive BL Lac
sample at 37 GHz. The BL Lac source list contains 398 sources, all of which were observed
at least once. Roughly 34% of the sample was detected at S/N > 4. Most of the detected
sources were LBLs, being intrinsically more luminous at radio wavelengths than HBLs.
Acknowledgements. The authors made use of the database CATS (Verkhodanov et al.
1997) of the Special Astrophysical Observatory.
References
Fossati, G., Maraschi, L., Celotti, A., Comastri, A. and Ghisellini, G.: MNRAS, 1998, 299,
433.
Nieppola, E., Tornikoski, M. and Valtaoja E.: A&A, 2006, 445, 441.
Verkhodanov, O.V., Trushkin, S.A., Andernach, H. and Chernenkov, V.N.: ASPC, 1997,
125, 322.