Surveys of the Cosmic X-Ray Background

Brandt, W. N.; Yang, Guang

doi:10.1007/978-981-16-4544-0_130-1

“…Above 0.7 keV, the emission from the CXB becomes the dominant component. At higher energies (E ≫ 1.5 keV), the integrated emission from faint and unresolved X-ray point sources (CXB, Gilli et al 2007;Brandt & Yang 2021) dominates the emission. In addition, a minor but non-negligible contribution may come from patches of very hot interstellar medium (ISM; kT ≃ 0.7−1 keV; Ponti et al 2023).…”

Section: Energy Bandmentioning

confidence: 99%

Broadband maps of eROSITA and their comparison with the ROSAT survey

Zheng,

Ponti,

Freyberg

et al. 2024

A&A

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By June of 2020, the extended ROentgen Survey with an Imaging Telescope Array ( ) on board the Spectrum Roentgen Gamma observatory had completed its first of the planned eight X-ray all-sky survey (eRASS1). The large effective area of the X-ray telescope makes it ideal for a survey of the faint X-ray diffuse emission over half of the sky with an unprecedented energy resolution and position accuracy. In this work, we produce the X-ray diffuse emission maps of the eRASS1 data with a current calibration, covering the energy range from 0.2 to 8.0 keV. We validated these maps by comparison with X-ray background maps derived from the All Sky Survey (RASS). We generated X-ray images with a pixel area of 9 arcmin$^2$ using the observations available to the German consortium. The contribution of the particle background to the photons was subtracted from the final maps. We also subtracted all the point sources above a flux threshold dependent on the goal of the subtraction, exploiting the eRASS1 catalog that will soon be available. The accuracy of the eRASS1 maps is shown by a flux match to the RASS X-ray maps, obtained by converting the rates into equivalent count rates in the standard energy bands R4, R5, R6, and R7, within 1.25sigma . We find small residual deviations in the R4, R5, and R6 bands, where tends to observe lower flux than (sim 11<!PCT!>), while a better agreement is achieved in the R7 band (sim 1<!PCT!>). The eRASS maps exhibit lower noise levels than RASS maps at the same resolution above 0.3 keV. We report the average surface brightness and total flux of different large sky regions as a reference. The detection of faint emission from diffuse hot gas in the Milky Way is corroborated by the consistency of the eRASS1 and RASS maps shown in this paper and by their comparable flux dynamic range.

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“…However, Compton-thick AGN are one of the most difficult classes of AGN to detect and study (Hickox and Alexander, 2018;Asmus et al, 2020;Brandt and Yang, 2022). For energies E < 10 keV, the intrinsic X-ray flux from the corona is mostly extinguished via the photoelectric effect and only a few percent of the intrinsic flux escapes (Gupta et al, 2021).…”

Section: The Prevalence Of Obscured Accretion Onto Supermassive Black...mentioning

confidence: 99%

The High-Energy X-ray Probe (HEX-P): the circum-nuclear environment of growing supermassive black holes

Boorman,

Torres-Albà,

Annuar

et al. 2024

Front. Astron. Space Sci.

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3

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Ever since the discovery of the first active galactic nuclei (AGN), substantial observational and theoretical effort has been invested into understanding how massive black holes have evolved across cosmic time. Circum-nuclear obscuration is now established as a crucial component, with almost every AGN observed known to display signatures of some level of obscuration in their X-ray spectra. However, despite more than six decades of effort, substantial open questions remain: how does the accretion power impact the structure of the circum-nuclear obscurer? What are the dynamical properties of the obscurer? Can dense circum-nuclear obscuration exist around intrinsically weak AGN? How many intermediate mass black holes occupy the centers of dwarf galaxies? In this paper, we showcase a number of next-generation prospects attainable with the High-Energy X-ray Probe (HEX-P1) to contribute toward solving these questions in the 2030s. The uniquely broad (0.2–80 keV) and strictly simultaneous X-ray passband of HEX-P makes it ideally suited for studying the temporal co-evolution between the central engine and circum-nuclear obscurer. Improved sensitivities and reduced background will enable the development of spectroscopic models complemented by current and future multi-wavelength observations. We show that the angular resolution of HEX-P both below and above 10 keV will enable the discovery and confirmation of accreting massive black holes at both low accretion power and low black hole masses even when concealed by thick obscuration. In combination with other next-generation observations of the dusty hearts of nearby galaxies, HEX-P will be pivotal in paving the way toward a complete picture of black hole growth and galaxy co-evolution.

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“…SMBHs grow primarily through rapid accretion when they are observed as active galactic nuclei (AGNs); mergers are an additional growth mode. X-ray emission is known to be a good indicator of AGN activity because of its universality among AGNs, high penetrating power through obscuration, and low dilution from galaxy starlight (e.g., Brandt & Alexander 2015;Brandt & Yang 2022). Therefore, X-ray surveys can be used to constrain the accretion distribution and the black hole accretion rate (BHAR = dM BH /dt) of SMBHs (e.g., Aird et al 2012Aird et al , 2018Bongiorno et al 2012Bongiorno et al , 2016Georgakakis et al 2017;Wang et al 2017;Yang et al 2017;Yang et al 2018;Ni et al 2019;Yang et al 2019;Ni et al 2021b).…”

Section: Introductionmentioning

confidence: 99%

Mapping the Growth of Supermassive Black Holes as a Function of Galaxy Stellar Mass and Redshift

Zou,

Yu,

Brandt

et al. 2024

ApJ

6

0

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The growth of supermassive black holes is strongly linked to their galaxies. It has been shown that the population mean black hole accretion rate ( BHAR ¯ ) primarily correlates with the galaxy stellar mass (M ⋆) and redshift for the general galaxy population. This work aims to provide the best measurements of BHAR ¯ as a function of M ⋆ and redshift over ranges of 109.5 < M ⋆ < 1012 M ⊙ and z < 4. We compile an unprecedentedly large sample with 8000 active galactic nuclei (AGNs) and 1.3 million normal galaxies from nine high-quality survey fields following a wedding cake design. We further develop a semiparametric Bayesian method that can reasonably estimate BHAR ¯ and the corresponding uncertainties, even for sparsely populated regions in the parameter space. BHAR ¯ is constrained by X-ray surveys sampling the AGN accretion power and UV-to-infrared multiwavelength surveys sampling the galaxy population. Our results can independently predict the X-ray luminosity function (XLF) from the galaxy stellar mass function (SMF), and the prediction is consistent with the observed XLF. We also try adding external constraints from the observed SMF and XLF. We further measure BHAR ¯ for star-forming and quiescent galaxies and show that star-forming BHAR ¯ is generally larger than or at least comparable to the quiescent BHAR ¯ .

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Surveys of the Cosmic X-Ray Background

Cited by 7 publications

References 139 publications

Broadband maps of eROSITA and their comparison with the ROSAT survey

Broadband maps of eROSITA and their comparison with the ROSAT survey

The High-Energy X-ray Probe (HEX-P): the circum-nuclear environment of growing supermassive black holes

Mapping the Growth of Supermassive Black Holes as a Function of Galaxy Stellar Mass and Redshift

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