arXiv:1110.1794·v1·Cosmology and Nongalactic Astrophysics
Radio observations of the first three-month Fermi-AGN at 4.8 GHz
Xiang Liu (1) · Hua-Gang Song (1,2) · Jun Liu (1) · Zhen Ding (1) · Nicola Marchili (3) · Thomas P. Krichbaum (3) · Lars Fuhrmann (3) · Anton Zensus (3) · Tao An (4) · ((1) Xinjiang Astronomical Observatory, CAS, (2) Graduate University of CAS, (3) MPIfR, (4) Shanghai Observatory, CAS)
Abstract
Using the Urumqi 25m radio telescope, sources from the first three-month Fermi-LAT detected AGN catalog with declination >0 were observed in 2009 at 4.8 GHz. The radio flux density appears to correlate with the gamma-ray intensity. Intra-day variability (IDV) observations were performed in March, April and May in 2009 for selected 42 gamma-ray bright blazars, and 60% of them show evident flux variability at 4.8 GHz during the IDV observations, the IDV detection rate is higher than that in previous flat-spectrum AGN samples. The IDV appears more often in the VLBI-core dominant blazars, and the non-IDV blazars show relatively `steeper' spectral indices than the IDV blazars. Pronounced inter-month variability has been found in two BL Lac objects: J0112+2244 and J0238+1636.
Comments: 10 pages, 3 figures, accepted for publication in RAA