期刊
ASTRONOMY & ASTROPHYSICS
卷 655, 期 -, 页码 -出版社
EDP SCIENCES S A
DOI: 10.1051/0004-6361/202140852
关键词
galaxies: active; galaxies: nuclei; quasars: general; quasars: supermassive black holes
资金
- INAF [Ob.Fun. 1.05.03.01.09]
- NASA [AR7-18013X, NAS8-03060]
- Fondazione Cassa di Risparmio Firenze [45780]
- Alfred P. Sloan Foundation
- US Department of Energy Office of Science
- Center for High-Performance Computing at the University of Utah
- Brazilian Participation Group
- Carnegie Institution for Science, Carnegie Mellon University
- Chilean Participation Group
- French Participation Group
- Harvard-Smithsonian Center for Astrophysics
- Instituto de Astrofisica de Canarias
- Johns Hopkins University
- Kavli Institute for the Physics and Mathematics of the Universe (IPMU)/University of Tokyo
- Korean Participation Group
- Lawrence Berkeley National Laboratory
- Leibniz Institut fur Astrophysik Potsdam (AIP)
- Max-Planck-Institut fur Astronomie (MPIA Heidelberg)
- Max-Planck-Institut fur Astrophysik (MPA Garching)
- Max-Planck-Institut fur Extraterrestrische Physik (MPE)
- National Astronomical Observatories of China
- New Mexico State University
- New York University
- University of Notre Dame
- Observatario Nacional/MCTI
- Ohio State University
- Pennsylvania State University
- Shanghai Astronomical Observatory
- United Kingdom Participation Group
- Universidad Nacional Autonoma de Mexico
- University of Arizona
- University of Colorado Boulder
- University of Oxford
- University of Portsmouth
- University of Utah
- University of Virginia
- University ofWashington
- University of Wisconsin
- Vanderbilt University
- Yale University
- [HST-AR-13240.009]
The study reveals a non-linear relation between ultraviolet and X-ray emissions in quasars, which remains constant over different cosmic epochs, indicating a consistent coupling mechanism between the accretion disc and hot corona. Additionally, a decrease in dispersion at higher redshifts suggests that quasars can serve as reliable cosmological distance indicators, especially in regions with limited cosmological probes.
We present a study of the relation between X-rays and ultraviolet emission in quasars for a sample of broad-line, radio-quiet objects obtained from the cross-match of the Sloan Digital Sky Survey DR14 with the latest Chandra Source Catalog 2.0 (2332 quasars) and the Chandra COSMOS Legacy survey (273 quasars). The non-linear relation between the ultraviolet (at 2500 angstrom, L-UV) and the X-ray (at 2 keV, L-X) emission in quasars has been proved to be characterised by a smaller intrinsic dispersion than the observed one, as long as a homogeneous selection, aimed at preventing the inclusion of contaminants in the sample, is fulfilled. By leveraging on the low background of Chandra, we performed a complete spectral analysis of all the data available for the SDSS-CSC2.0 quasar sample (i.e. 3430 X-ray observations), with the main goal of reducing the uncertainties on the source properties (e.g. flux, spectral slope). We analysed whether any evolution of the L-X - L-UV relation exists by dividing the sample in narrow redshift intervals across the redshift range spanned by our sample, z similar or equal to 0.5-4. We find that the slope of the relation does not evolve with redshift and it is consistent with the literature value of 0.6 over the explored redshift range, implying that the mechanism underlying the coupling of the accretion disc and hot corona is the same at the different cosmic epochs. We also find that the dispersion decreases when examining the highest redshifts, where only pointed observations are available. These results further confirm that quasars are 'standardisable candles', that is we can reliably measure cosmological distances at high redshifts where very few cosmological probes are available.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据