First Study of Combined Blazar Light Curves with FACT and HAWC
Abstract
For studying variable sources like blazars, it is crucial to achieve unbiased monitoring, either with dedicated telescopes in pointing mode or survey instruments. At TeV energies, the High Altitude Water Cherenkov (HAWC) observatory monitors approximately two thirds of the sky every day. It uses the water Cherenkov technique, which provides an excellent duty cycle independent of weather and season. The First G-APD Cherenkov Telescope (FACT) monitors a small sample of sources with better sensitivity, using the imaging air Cherenkov technique. Thanks to its camera with silicon-based photosensors, FACT features an excellent detector performance and stability and extends its observations to times with strong moonlight, increasing the duty cycle compared to other imaging air Cherenkov telescopes. As FACT and HAWC have overlapping energy ranges, a joint study can exploit the longer daily coverage given that the observatories' locations are offset by 5.3 hours. Furthermore, the better sensitivity of FACT adds a finer resolution of features on hour-long time scales, while the continuous duty cycle of HAWC ensures evenly sampled long-term coverage. Thus, the two instruments complement each other to provide a more complete picture of blazar variability. In this presentation, the first joint study of light curves from the two instruments will be shown, correlating long-term measurements with daily sampling between air and water Cherenkov telescopes. The presented results focus on the study of the variability of the bright blazars Mrk 421 and Mrk 501 during the last two years featuring various flaring activities.
Cite
@article{arxiv.1610.06627,
title = {First Study of Combined Blazar Light Curves with FACT and HAWC},
author = {Daniela Dorner and Robert J. Lauer and : and Jan Adam and Max Ahnen and Dominik Baack and Matteo Balbo and Matthias Bergmann and Adrian Biland and Michael Blank and Thomas Bretz and Kai Brügge and Jens Buss and Anton Dmytiiev and Sabrina Einecke and Christina Hempfling and Dorothee Hildebrand and Gareth Hughes and Lena Linhoff and Karl Mannheim and Sebastian Müller and Dominik Neise and Andrii Neronov and Maximilian Noethe and Aleksander Paravac and Felicitas Pauss and Wolfgang Rhode and Amit Shukla and Fabian Temme and Julia Thaele and Roland Walter},
journal= {arXiv preprint arXiv:1610.06627},
year = {2017}
}
Comments
6 pages, 2 figures. Contribution to the 6th International Symposium on High Energy Gamma-Ray Astronomy (Gamma2016), Heidelberg, Germany. To be published in the AIP Conference Proceedings