Using the Urumqi 25 m radio telescope, sources from the first three months of the Fermi-large area telescope detected active galactic nuclei (AGN) catalog with a declination of 〉 0° were observed in 2009 at 4....Using the Urumqi 25 m radio telescope, sources from the first three months of the Fermi-large area telescope detected active galactic nuclei (AGN) catalog with a declination of 〉 0° were observed in 2009 at 4.8 GHz. The radio flux density ap- peared to correlate with the γ-ray intensity. Intra-day variability (IDV) observations were performed in March, April and May 2009 for 42 selected γ-ray bright blazars, and ~60% of them showed evidence of flux variability at 4.8 GHz during the IDV observations. The IDV detection rate was higher than that in previous flat-spectrum AGN samples. IDV appeared more often in the very long baseline interferometry-core dominant blazars, and the non-IDV blazars showed relatively "steeper" spectral in- dices than the IDV blazars. Pronounced inter-month variability was also found in two BL Lac objects: J0112+2244 and J0238+1636.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 11073036)the NationalBasic Research Program of China (973 Program 2009CB824800)
文摘Using the Urumqi 25 m radio telescope, sources from the first three months of the Fermi-large area telescope detected active galactic nuclei (AGN) catalog with a declination of 〉 0° were observed in 2009 at 4.8 GHz. The radio flux density ap- peared to correlate with the γ-ray intensity. Intra-day variability (IDV) observations were performed in March, April and May 2009 for 42 selected γ-ray bright blazars, and ~60% of them showed evidence of flux variability at 4.8 GHz during the IDV observations. The IDV detection rate was higher than that in previous flat-spectrum AGN samples. IDV appeared more often in the very long baseline interferometry-core dominant blazars, and the non-IDV blazars showed relatively "steeper" spectral in- dices than the IDV blazars. Pronounced inter-month variability was also found in two BL Lac objects: J0112+2244 and J0238+1636.