Physical Sciences and Mathematics Commons^™

A New Activity Phase Of The Blazar 3c 454.3 Multifrequency Observations By The Webt And Xmm-Newton In 2007-2008, Niall Smith, Et. Al.

Blackrock Castle Observatory Publications

Aims: The Whole Earth Blazar Telescope (WEBT) consortium has been monitoring the blazar 3C 454.3 from the radio to the optical bands since 2004 to study its emission variability properties.

Methods: We present and analyse the multifrequency results of the 2007-2008 observing season, including XMM-Newton observations and near-IR spectroscopic monitoring, and compare the recent emission behaviour with the past one. The historical mm light curve is presented here for the first time.

Results: In the optical band we observed a multi-peak outburst in July-August 2007, and other faster events in November 2007-February 2008. During these outburst phases, several episodes of …

Observation Of Gamma-Ray Emission From The Galaxy M87 Above 250 Gev With Veritas, P. T. Reynolds, Et. Al.

Physical Sciences Publications

The multiwavelength observation of the nearby radio galaxy M87 provides a unique opportunity to study in detail processes occurring in active galactic nuclei from radio waves to TeV γ-rays. Here we report the detection of γ-ray emission above 250 GeV from M87 in spring 2007 with the VERITAS atmospheric Cerenkov telescope array and discuss its correlation with the X-ray emission. The γ-ray emission is measured to be pointlike with an intrinsic source radius less than 4.5'. The differential energy spectrum is fitted well by a power-law function: dΦ/dE = (7.4 ± 1.3stat ± 1.5sys)(E/TeV)(− 2.31 ± 0.17stat ± 0.2sys) 10−9 …