The Contribution of AGN Accretion Disks to Hydrogen Reionization

Zeltyn, Grisha; Trakhtenbrot, Benny

doi:10.3847/1538-4357/ac4783

Cited by 7 publications

(7 citation statements)

References 121 publications

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“…These values are consistent with previous studies that have considered samples of CL AGNs (see, e.g., Lawrence et al 2016;Rumbaugh et al 2018;Graham et al 2020;Potts & Villforth 2021). In a recent work by Zeltyn et al (2024), where the authors make a compendium of newly discovered CL AGNs using proprietary SDSS V data sets, they too find a median Eddington ratio for their sample of 113 CL AGNs of −1.522, while for their control sample of CL AGNs matched from the SDSS DR16 (Wu & Shen 2022) the median Eddington ratio is −1.602, which are in close agreement with the median values for our sample. This furthers the hypothesis that CL AGNs, if affected by intrinsic changes, are more frequent for sources with Eddington ratios around 10 −2 .…”

Section: Black Hole Mass and Eddington Ratiossupporting

confidence: 92%

Changing-look Active Galactic Nuclei. I. Tracking the Transition on the Main Sequence of Quasars

Panda,

Śniegowska

2024

ApJS

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This paper is the first in a series of papers that prepare and analyze spectral and other properties for a database of already-discovered changing-look active galactic nuclei (CL AGNs). Here we focus on the spectral fitting and analysis of broad emission lines in a sample of 93 CL AGNs collected from the literature with existing Sloan Digital Sky Survey (SDSS)/Baryon Oscillation Spectroscopic Survey (BOSS)/extended-BOSS spectroscopy where the Hβ emission-line profile does not completely disappear in any epochs. Additionally, we have gathered older/newer spectral epochs from all the available SDSS data releases to make the database more complete. We use PyQSOFit and perform a homogeneous spectral decomposition of all of our SDSS spectra and tabulate the AGN continuum and emission-line properties per epoch per source, chronologically. This further allows us to categorize the sources in our sample as Turn-On or Turn-Off and subsequently check for repeated occurrences of such phases. We then estimate the black hole mass (M BH) and the Eddington ratio (λ Edd) per epoch per source where the required parameters are available and well estimated. We demonstrate the movement of the source in the M BH–λ Edd plane, allowing us to check for systematic changes in the source’s fundamental properties. We then track their transition along the optical plane of the Eigenvector 1 schema and categorize sources that either stay within the same population (A or B) or make an interpopulation movement as a function of spectral epoch. We also test the Balmer decrement (Hα/Hβ) of a subset of our sample of CL AGNs as a function of time and AGN luminosity.

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Section: Black Hole Mass and Eddington Ratiossupporting

confidence: 92%

Changing-look Active Galactic Nuclei. I. Tracking the Transition on the Main Sequence of Quasars

Panda,

Śniegowska

2024

ApJS

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“…A caveat is that it is possible that our broad Hα line selection implicitly selects for dusty viewing angles, potentially allowing for a similarly high number density of faint AGN with unobscured lines of sight. While this can be addressed with alternative selection methods, we note that a high fraction of obscured SMBHs might explain the short UV luminous (unobscured) timescales inferred from small proximity zone sizes around high-redshift quasars (e.g., Eilers et al 2017;Davies et al 2019a;Zeltyn & Trakhtenbrot 2022;Satyavolu et al 2023).…”

Section: Implications For Reionizationmentioning

confidence: 99%

Little Red Dots: An Abundant Population of Faint Active Galactic Nuclei at z ∼ 5 Revealed by the EIGER and FRESCO JWST Surveys

Matthee,

Naidu,

Brammer

et al. 2024

ApJ

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Characterizing the prevalence and properties of faint active galactic nuclei (AGNs) in the early Universe is key for understanding the formation of supermassive black holes (SMBHs) and determining their role in cosmic reionization. We perform a spectroscopic search for broad Hα emitters at z ≈ 4–6 using deep JWST/NIRCam imaging and wide field slitless spectroscopy from the EIGER and FRESCO surveys. We identify 20 Hα lines at z = 4.2–5.5 that have broad components with line widths from ∼1200–3700 km s−1, contributing ∼30%–90% of the total line flux. We interpret these broad components as being powered by accretion onto SMBHs with implied masses ∼107–8 M ⊙. In the UV luminosity range M UV,AGN+host = −21 to −18, we measure number densities of ≈10−5 cMpc−3. This is an order of magnitude higher than expected from extrapolating quasar UV luminosity functions (LFs). Yet, such AGN are found in only <1% of star-forming galaxies at z ∼ 5. The number density discrepancy is much lower when compared to the broad Hα LF. The SMBH mass function agrees with large cosmological simulations. In two objects, we detect complex Hα profiles that we tentatively interpret as caused by absorption signatures from dense gas fueling SMBH growth and outflows. We may be witnessing early AGN feedback that will clear dust-free pathways through which more massive blue quasars are seen. We uncover a strong correlation between reddening and the fraction of total galaxy luminosity arising from faint AGN. This implies that early SMBH growth is highly obscured and that faint AGN are only minor contributors to cosmic reionization.

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“…Giallongo et al 2015;Madau & Haardt 2015;Yoshiura et al 2017;Bosch-Ramon 2018;Giallongo et al 2019;Dayal et al 2020;Torres-Albà et al 2020) and against (e.g. Stark 2016;Qin et al 2017;D'Aloisio et al 2017;Hassan et al 2018;Mitra et al 2018;Parsa et al 2018;Zeltyn & Trakhtenbrot 2022) scenarios where AGN provide significant contributions to the reionizing process in the early Universe. Here, we calculate the emissivity of UV photons at 1500Å for the two populations by integrating the fits to our luminosity functions between the luminosity range of −30 < 𝑀 UV < −15 [𝜌 1500 = ∫ −15 −30 Φ(𝑀)𝐿 (𝑀)𝑑𝑀].…”

Section: Ionizing Emissivity Of Agn In the Epoch Immediately Post-rei...mentioning

confidence: 99%

The total rest-frame UV luminosity function from $3 < z < 5$: A simultaneous study of AGN and galaxies from $-28

Adams¹,

Bowler²,

Jarvis³

et al. 2022

Preprint

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We present measurements of the rest-frame ultraviolet luminosity function (UV LF) at redshifts 𝑧 = 3, 𝑧 = 4 and 𝑧 = 5, using 96894, 38655 and 7571 sources respectively to map the transition between AGN and galaxy-dominated ultraviolet emission shortly after the epoch of reionization. Sources are selected using a comprehensive photometric redshift approach, using 10 deg 2 of deep extragalactic legacy fields covered by both HSC and VISTA. The use of template fitting spanning a wavelength range of 0.3-2.4𝜇m achieves 80-90 per cent completeness, much higher than classical colour-colour cut methodology. The measured LF encompasses −26 < 𝑀 UV < −19.25(−20.5) at 𝑧 = 3(5). This is further extended to −28.5 < 𝑀 UV < −16 using complementary results from other studies, allowing for the simultaneous fitting of the combined AGN and galaxy LF. We find that there are fewer UV luminous galaxies (𝑀 UV < −22) at 𝑧 ∼ 3 than 𝑧 ∼ 4, indicative of an onset of widespread quenching alongside dust obscuration, and that the evolution of the AGN LF is much more rapid than the galaxy LF, with their number density rising by around 2 orders of magnitude from 3 < 𝑧 < 6. We also find that it remains difficult to determine if a double power law (DPL) functional form is preferred over the Schechter function to describe the galaxy UV LF with photometric data alone. Estimating the Hydrogen ionizing photon budget from our UV LFs, we find that AGN can contribute to, but cannot solely maintain, the reionization of the Universe at 𝑧 = 3 − 5. However, the rapidly evolving AGN LF strongly disfavours a significant contribution within the EoR.

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The Contribution of AGN Accretion Disks to Hydrogen Reionization

Cited by 7 publications

References 121 publications

Changing-look Active Galactic Nuclei. I. Tracking the Transition on the Main Sequence of Quasars

Changing-look Active Galactic Nuclei. I. Tracking the Transition on the Main Sequence of Quasars

Little Red Dots: An Abundant Population of Faint Active Galactic Nuclei at z ∼ 5 Revealed by the EIGER and FRESCO JWST Surveys

The total rest-frame UV luminosity function from $3 < z < 5$: A simultaneous study of AGN and galaxies from $-28

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