The Chandra view of the relation between X-ray and UV emission in quasars

Abstract

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 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. 3,430 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 $L_X-L_O$ relation exists by dividing the sample in narrow redshift intervals across the redshift range spanned by our sample, $z\simeq 0.5-4$. 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.

arXiv comment20 pages, 14 figures, accepted for publication in A&A

References in corpus (54)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• emcee: The MCMC Hammer
• Correcting for the Effects of Interstellar Extinction
• The Complete Light-curve Sample of Spectroscopically Confirmed Type Ia Supernovae from Pan-STARRS1 and Cosmological Constraints from The Combined Pantheon Sample
• Atomic Data for Astrophysics. II. New Analytic Fits for Photoionization Cross Sections of Atoms and Ions
• Large Magellanic Cloud Cepheid Standards Provide a 1% Foundation for the Determination of the Hubble Constant and Stronger Evidence for Physics Beyond LambdaCDM
• A Catalog of Quasar Properties from SDSS DR7
• Some Aspects of Measurement Error in Linear Regression of Astronomical Data
• Spectral Energy Distributions and Multiwavelength Selection of Type 1 Quasars
• The COSMOS2015 Catalog: Exploring the 1<z<6 Universe with half a million galaxies
• An 800-million-solar-mass black hole in a significantly neutral Universe at redshift 7.5
• UltraVISTA: a new ultra-deep near-infrared survey in COSMOS
• A Structure for Quasars
• The Chandra Source Catalog
• The X-ray-to-Optical Properties of Optically-Selected Active Galaxies Over Wide Luminosity and Redshift Ranges
• The Chandra COSMOS Legacy survey: overview and point source catalog
• The Sloan Digital Sky Survey Quasar Catalog: Fourteenth Data Release
• The Chandra COSMOS Survey, I: Overview and Point Source Catalog
• The Sloan Digital Sky Survey Quasar Catalog: twelfth data release
• The X-ray to optical-UV luminosity ratio of X-ray selected Type 1 AGN in XMM-COSMOS
• The X-ray Properties of the Most-Luminous Quasars from the Sloan Digital Sky Survey
• A Catalog of Broad Absorption Line Quasars in Sloan Digital Sky Survey Data Release 5
• The VLA-COSMOS 3 GHz Large Project: Continuum data and source catalog release
• Quantifying Quasar Variability As Part of a General Approach To Classifying Continuously Varying Sources
• The Chandra COSMOS Legacy survey: optical/IR identifications
• X-ray emission from radio-quiet quasars in the SDSS Early Data Release. The alpha_ox dependence upon UV luminosity
• The Chandra COSMOS Survey: III. Optical and Infrared Identification of X-ray Point Sources
• A Hubble Diagram for Quasars
• The tight relation between X-ray and ultraviolet luminosity of quasars
• A strong redshift dependence of the broad absorption line quasar fraction
• Quasars as standard candles III. Validation of a new sample for cosmological studies
• Magnetic reconnection: flares and coronal heating in Active Galactic Nuclei
• Tension with the flat ΛCDM model from a high redshift Hubble Diagram of supernovae, quasars and gamma-ray bursts
• Accretion disc coronae as magnetic reservoirs
• Quasars as standard candles I: The physical relation between disc and coronal emission
• A simple model for magnetic reconnection heated corona
• Prevalence of X-ray variability in the Chandra Deep Field South
• The MIXR sample: AGN activity versus star formation across the cross-correlation of WISE, 3XMM, and FIRST/NVSS
• Dependence of the optical/UV variability on the emission line properties and Eddington ratio in active galactic nuclei
• The X-ray Energy Dependence of the Relation between Optical and X-ray Emission in Quasars
• [O III] Equivalent Width and Orientation Effects in Quasars
• The Chandra survey of the COSMOS field II: source detection and photometry
• Quasars as standard candles II: The non linear relation between UV and X-ray emission at high redshifts
• The most luminous blue quasars at $3.0<z<3.3$. I. A tale of two X-ray populations
• Ensemble X-ray variability of Active Galactic Nuclei. II. Excess Variance and updated Structure Function
• Ensemble X-ray variability of Active Galactic Nuclei from serendipitous source catalogues
• A long term study of AGN X-ray variability. Structure function analysis on a ROSAT-XMM quasar sample
• Orientation effects on spectral emission features of quasars
• Cosmography by orthogonalized logarithmic polynomials
• Variability and the X-ray/UV ratio of Active Galactic Nuclei
• Spectral Energy Distributions of Type 1 AGN in XMM-COSMOS Survey II - Shape Evolution
• The X-ray Variability of AGN and its Implications for Observations of Galaxy Clusters
• Orientation effects on the near-infrared broad band emission of quasars
• Exploring the Variable Sky with the Sloan Digital Sky Survey

Cited by in corpus (22)

• Challenges for $\Lambda$CDM: An update
• Revealing Intrinsic Flat $\Lambda$CDM Biases with Standardizable Candles
• On Larger $H_0$ Values in the CMB Dipole Direction
• Quasar standardization: Overcoming Selection Biases and Redshift Evolution
• Gamma-Ray Bursts, Quasars, Baryonic Acoustic Oscillations, and Supernovae Ia: new statistical insights and cosmological constraints
• Reducing the uncertainty on the Hubble constant up to 35\% with an improved statistical analysis: different best-fit likelihoods for Supernovae Ia, Baryon Acoustic Oscillations, Quasars, and Gamma-Ray Bursts
• Tensions with the flat $\mathbf{\Lambda }$CDM model from high-redshift cosmography
• Quasars as high-redshift standard candles
• Cosmological constraints on dark energy models using DESI BAO 2024
• Can the Distance-Redshift Relation Be Determined from Correlations Between Luminosities?
• Redshift Evolution and Non-Universal Dispersion of Quasar Luminosity Correlation
• Deep XMM-Newton Observations of an X-ray Weak, Broad Absorption Line Quasar at $z=6.5$
• The X-ray Luminosity Function Evolution of Quasars and the Correlation Between the X-ray and Ultraviolet Luminosities
• Wavelength Dependences of the Optical/UV and X-ray Luminosity Correlations of Quasars
• Discovery of the most luminous quasar of the last 9 Gyr
• The intrinsic X-ray luminosity distribution of an optically-selected SDSS quasar population
• MAMBO -- An empirical galaxy and AGN mock catalogue for the exploitation of future surveys
• Unveiling the Universe with Emerging Cosmological Probes
• Quasars as high-redshift standard candles
• Revisiting the X-ray-to-UV relation of Quasars in the era of all-sky surveys
• The X-ray$-$UV Luminosity Relation of eROSITA Quasars
• SRG/eROSITA-SDSS view on the relation between X-ray and UV emission for quasars