Multi-color Optical Variability of the TeV Blazar Mrk 501 in the Low-State - Astrophysics

Abstract: We report results based on the monitoring of the BL Lac object Mrk 501 in theoptical B, V and R passbands from March to May 2000. Observations spread over12 nights were carried out using 1.2 meter Mount Abu Telescope, India and 61 cmTelescope at Sobaeksan Astronomy Observatory, South Korea. The aim is to studythe intra-day variability IDV, short term variability and color variabilityin the low state of the source. We have detected flux variation of 0.05 mag inthe R-band in time scale of 15 min in one night. In the B and V passbands, wehave less data points and it is difficult to infer any IDVs. Short term fluxvariations are also observed in the V and R bands during the observing run. Nosignificant variation in color B$-$R has been detected but V$-$R showsvariation during the present observing run.Assuming the shortest observed time scale of variability 15 min torepresent the disk instability or pulsation at a distance of 5 Schwarschildradii from the black hole BH, mass of the central BH is estimated $\sim$ 1.20$\times$ 10$^{8} M {\odot}$.

Author: A. C. Gupta 1, W. G. Deng 2,1, U. C. Joshi 3, J. M. Bai 1, M. G. Lee 4 1 National Astronomical Observatories - Yunnan Observatory

Source: https://arxiv.org/