Quasars as standard candles III. Validation of a new sample for cosmological studies
E. Lusso, G. Risaliti, E. Nardini, G. Bargiacchi, M. Benetti, S. Bisogni, S. Capozziello, F. Civano, L. Eggleston, M. Elvis, G. Fabbiano, R. Gilli, A. Marconi, … 展开作者
E. Lusso, G. Risaliti, E. Nardini, G. Bargiacchi, M. Benetti, S. Bisogni, S. Capozziello, F. Civano, L. Eggleston, M. Elvis, G. Fabbiano, R. Gilli, A. Marconi, M. Paolillo, E. Piedipalumbo, F. Salvestrini, M. Signorini, C. Vignali
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24 pages, 17 figures, accepted for publication in A&A
We present a new catalogue of ~2,400 optically selected quasars with spectroscopic redshifts and X-ray observations from either Chandra or XMM-Newton. The sample can be used to investigate the non-linear relation between the UV and X-ray luminosity of quasars, and to build a Hubble diagram up to redshift z~7.5. We selected sources that are neither reddened by dust in the optical/UV nor obscured by gas in the X-rays, and whose X-ray fluxes are free from flux-limit related biases. After checking for any possible systematics, we confirm, in agreement with our previous works, that (i) the X-ray to UV relation provides distance estimates matching those from supernovae up to z~1.5, and (ii) its slope shows no redshift evolution up to z~5. We provide a full description of the methodology for testing cosmological models, further supporting a trend whereby the Hubble diagram of quasars is well reproduced by the standard flat $Λ$CDM model up to z~1.5-2, but strong deviations emerge at higher redshifts. Since we have minimized all non-negligible systematic effects, and proven the stability of the $L_{\rm X}-L_{\rm UV}$ relation at high redshifts, we conclude that an evolution of the expansion rate of the Universe should be considered as a possible explanation for the observed deviation, rather than some systematic (redshift-dependent) effect associated with high-redshift quasars.
A tight non-linear relation between the X-ray and the optical-ultraviolet (UV) emission has been observed in Active Galactic Nuclei (AGN) over a wide range of redshift and several orders of magnitude in luminosity, suggesting the existence of an ubiquitous physical mechanism regulating the energy transfer between the accretion disc and the X-ray emitting corona. Recently, our group developed a method to use this relation in the observational cosmology, turning quasars into standardizable candles. This work has the main aim to investigate the potential evolution of this correction at high redsh…
The cosmological model is at present not tested between the redshift of the farthest observed supernovae (z ~ 1.4) and that of the Cosmic Microwave Background (z ~ 1,100). Here we introduce a new method to measure the cosmological parameters: we show that quasars can be used as "standard candles" by employing the non-linear relation between their intrinsic UV and X-ray emission as an absolute distance indicator. We built a sample of ~ 1,900 quasars with available UV and X-ray observations, and produced a Hubble Diagram up to z ~ 5. The analysis of the quasar Hubble Diagram, when used in combin…
A key component of the Dark Energy Spectroscopic Instrument (DESI) survey validation (SV) is a detailed visual inspection (VI) of the optical spectroscopic data to quantify key survey metrics. In this paper we present results from VI of the quasar survey using deep coadded SV spectra. We show that the majority (~70%) of the main-survey targets are spectroscopically confirmed as quasars, with ~16% galaxies, ~6% stars, and ~8% low-quality spectra lacking reliable features. A non-negligible fraction of the quasars are misidentified by the standard spectroscopic pipeline but we show that the major…
By applying different statistically robust methods, we analyze the time-lag between the continuum and ionized line-emission (Mg II line) light curves for the distant bright quasar CTS C$30.10$ (redshift $z \sim 0.9$). The data were obtained by the 10-meter SALT telescope in South Africa. In detail, we demonstrate the application of several methods using interpolated cross-correlation function (ICCF), discrete correlation function (DCF), z-transformed discrete correlation function (zDCF), von Neumann estimator, and the JAVELIN code package. In particular, we discuss the uncertainties of these m…
Immensely bright quasars and radio-loud active galactic nuclei (AGNs) provide an enticing opportunity to construct standard candles detectable up to the very early universe. An analytic theory is proposed to measure the distance to powerful \citeauthor{FR+1974} type-II radio sources based on their integrated flux density across a broad range of radio frequencies, and the angular size and axis ratio of their synchrotron-emitting lobes. This technique can be used at low-redshift to construct absolute standard candles in conjunction with X-ray observations of the host cluster, or at high-redshift…
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 (2,332 quasars) and the Chandra COSMOS Legacy survey (273 quasars). The non-linear relation between the ultraviolet (at 2500 A, $L_{O}$) 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…
We explore the evolution of the time variability (in the optical $g$-band and on timescales of weeks to years) of SDSS Stripe 82 quasars along the quasar main sequence. A parent sample of $1004$ quasars within $0.5\leq z \leq 0.89$ are used for our statistical studies, we then make subsamples from our parent sample: a subsample of $246$ quasars with similar luminosities, and a subsample of $399$ quasars with similar Rfe (i.e., the ratio of the equivalent width of FeII within $4435$--$4685\ \mathrmÅ$ to that of \Hbeta). We find the variability amplitude decreases with luminosity ($L_{\mathrm{bo…
We describe methods designed to determine the astrophysical parameters of quasars based on spectra coming from the red and blue spectrophotometers of the Gaia satellite. These methods principally rely on two already published algorithms that are the weighted principal component analysis and the weighted phase correlation. The presented approach benefits from a fast implementation; an intuitive interpretation as well as strong diagnostic tools on the potential errors that may arise during predictions. The production of a semi-empirical library of spectra as they will be observed by Gaia is also…
The most highly accreting quasars (xA) are of special interest in studies of the physics of AGNs and host galaxy evolution. Quasars accreting at high rates (L/LEdd $\sim$ 1) hold promise for use as 'standard candles': distance indicators detectable at very high redshift. However, their observational properties are largely unknown. A large sample of xA can clarify the main properties of quasars radiating near L/LEdd $\sim$ 1 in the Hb spectral range for redshift $\lt$ 0.8. We use selection criteria derived from 4DE1 studies to identify and analyze spectra for a sample of 334 candidate sources i…
SRG/eROSITA-SDSS view on the relation between X-ray and UV emission for quasars
Space Research Institute of the Russian Academy of Sciences（俄罗斯科学院空间研究所）；National Research University Higher School of Economics（国立高等经济大学）；Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理学研究所）；Ioffe Institute（约费物理技术研究所）；Kazan Federal University（喀山联邦大学）；Academy of Sciences of Tatarstan（鞑靼斯坦共和国科学院）
4MOST ChANGES: Catalog of high-redshift quasar candidates (4.5 < $z$ < 7) selected with SED fitting
Instituto de Estudios Astrofísicos, Universidad Diego Portales（智利道格拉斯·佩莱斯大学天体物理研究所）；Centre for Extragalactic Astronomy, Department of Physics, Durham University（杜伦大学物理学系河外天文中心）；Universidad Técnica Federico Santa María（费德里科·圣塔玛利亚理工大学）；Universidad de Tarapacá（塔拉帕卡大学）；European Southern Observatory（欧洲南方天文台）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）；Max-Planck-Institut für Astronomie（马克斯·普朗克天文学研究所）；INAF, Osservatorio di Astrofisica e Scienza dello Spazio (OAS)（意大利国家天体物理研究所空间科学与天体物理观测站）；International Gemini Observatory/NSF NOIRLab（国际双筒望远镜天文台/美国国家光学红外天文实验室）
The Dark Energy Spectroscopic Instrument (DESI) is carrying out a 5-year survey that aims to measure the redshifts of tens of millions of galaxies and quasars, including 8 million luminous red galaxies (LRGs) in the redshift range of $0.4<z<{\sim}\,1.0$. Here we present the selection of the DESI LRG sample and assess its spectroscopic performance using data from Survey Validation (SV) and the first 2 months of the Main Survey. The DESI LRG sample, selected using $g$, $r$, $z$, and $W1$ photometry from the DESI Legacy Imaging Surveys, is highly robust against imaging systematics. The sample has…
Building a Radio AGN Sample from Cosmic Morning -- The Radio High-Redshift Quasar Catalog (RHzQCat): I. Catalog from SDSS Quasars and Radio Surveys at $z > 3$
New Dynamical Measurements from a Lensed Quasar Sample: Joint Analysis Constrains the Mass Profile Evolution of Lens Galaxies
Yunnan University（云南大学）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；University of Chinese Academy of Sciences（中国科学院大学）；Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）；Dalian University of Technology（大连理工大学）；Zhengzhou University（郑州大学）；Nanchang University（南昌大学）
BASS LV. Connecting X-ray variability with AGN physical properties and a new path to Cosmological distances
Università degli Studi Roma Tre（罗马第三大学）；INAF – Osservatorio Astrofisico di Arcetri（意大利国家天体物理研究所阿切里天文台）；European Space Agency (ESA), European Space Research and Technology Centre (ESTEC)（欧洲空间局欧洲空间研究与技术中心）；INAF – Osservatorio Astronomico di Roma（意大利国家天体物理研究所罗马天文台）；INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna（意大利国家天体物理研究所博洛尼亚天文与空间科学台）；Pontificia Universidad Católica de Chile, Instituto de Astrofísica（智利天主教大学天体物理研究所）；Cahill Center for Astronomy and Astrophysics, California Institute of Technology（加州理工学院凯尔天文学与天体物理学中心）；Frontier Research Institute for Interdisciplinary Sciences, Tohoku University（东北大学跨学科前沿研究院）
