@article{10902/26541,
year = {2012},
url = {https://hdl.handle.net/10902/26541},
abstract = {We present the results of our X-ray, UV, and optical monitoring campaign of the first gravitationally lensed active galactic nucleus (AGN) from late 2009 to mid-2010. The trailing (B) image of the AGN 0957+561 showsthe intrinsic continuum variations that were predicted in advance based on observations of the leading (A) image in the gr optical bands. This multiwavelength variability of the B image allows us to carry out a reverberation mapping analysis in the radio-loud AGN 0957+561 at redshift z=1.41. We find that the U-band and r-band light curves are highly correlated with the g-band record, leading and trailing it by 3±1 days (U band) and 4±1 days (r band). These 1σ measurements are consistent with a scenario in which flares originated in the immediate vicinityof the supermassive black hole are thermally reprocessed in a standard accretion disk at ~10-20 Schwarzschild radii from the central dark object. We also report that the light curve for the X-ray emission with power-law spectrum is delayed with respect to those in theU gr bands by ~ 32 days. Hence, the central driving source cannotbe a standard corona emitting the observed power-law X-rays. This result is also supported by X-ray reprocessing simulations and the absence of X-ray reflection features in the spectrum of 0957+561. We plausibly interpret the lack of reflection and the 32 day delay as evidence for a power-law X-ray source in the base of the jet at a typical height of ~ 200 Schwarzschild radii. A central EUV source would drive the variability of 0957+561.},
organization = {The authors thank several colleagues and the anonymous referee for their valuable comments on preliminary versions of this paper. We also thank the staff of the Chandra X-ray Observatory, Liverpool Robotic Telescope (LRT), and Swift Multi-wavelength Observatory (SMO) for their kind interaction and support during the preparation of the project and the observation period. The Chandra Center is operated by the Smithsonian Astrophysical Observatory for and on behalf of the National Aeronautics and Space Administration (NASA) under contract NAS803060. The LRT is operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrof´ısica de Canarias (ORM-IAC) with support from the UK Science and Technology Facilities Council. The SMO is supported at Penn State University by NASA contract NAS5-00136. This paper is also based on observations made with the Nordic Optical Telescope, which is operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish ORM-IAC. This research has been supported by the Spanish Department of Science and Innovation grants AYA2007-67342-C03-02 and ESP2006-13608-C02-01, and University of Cantabria funds.},
publisher = {Institute of Physics Publishing},
publisher = {Astrophysical Journal, 744 (1), 47, 2012},
title = {Accretion onto the supermassive black hole in the high-redshift radio-loud AGN0957+561},
author = {Gil-Merino Rubio, Rodrigo and Goicoechea Santamaría, Luis Julián and Shalyapin, Vyacheslav and Braga, Vittorio Francesco},
}