AGN jets versus accretion as reionization sources

Torres-Albà, N.; Bosch‐Ramon, V.; Iwasawa, K.

doi:10.1051/0004-6361/201936047

Cited by 9 publications

(5 citation statements)

References 61 publications

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“…Indeed, this value corresponds to 82% of the UV background inferred by Davies et al (2018a), or alternatively to the 52% of the one by D' Aloisio et al (2018). A further correction of the z ∼ 6 ionizing background of +10% could be in place due to the impact of AGN jet lobes, according to Torres-Alba et al (2020). These effects can have important consequences on the role of AGNs and SFGs in the reionization of the Universe.…”

Section: The Ionizing Background At Z > 5 and Implications On Reioniz...mentioning

confidence: 99%

On the AGN nature of two UV bright sources at z_spec~5.5 in the CANDELS fields: an update of the AGN space density at M1450~-22.5

Grazian,

Giallongo,

Fiore

et al. 2020

Preprint

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It is a widespread opinion that hydrogen reionization is mainly driven by primeval star-forming galaxies, with a minor role of high-z active galactic nuclei. Recent observations, however, challenge this notion, indicating a number of issues related to a galaxy-driven reionization scenario. We provide here an updated assessment of the space density of relatively faint (M 1450 ∼ −22.5) AGNs at z spec ∼ 5.5 in order to improve the estimate of the photo-ionization rate contribution from accreting super massive black holes. Exploiting deep UV rest-frame ground-based spectra collected at the Very Large Telescope on the CANDELS/GOODS-South field and deep Chandra X-ray images in the CANDELS/GOODS-North and EGS areas, we find two relatively bright (M 1450 ∼ −22.5) AGNs at z spec ∼ 5.5. We derive an AGN space density of Φ = 1.29 × 10 −6 cM pc −3 at z ∼ 5.5 and M 1450 ∼ −22.5 by simply dividing their observed number by the cosmological volume in the range 5.0 < z < 6.1. Our estimate does not consider corrections for incompleteness, therefore it represents a lower limit, although uncertainties due to cosmic variance can still be significant. This value supports a high space density of AGNs at z > 5, in contrast with previous claims mostly based on standard color selection, possibly affected by significant incompleteness. Our estimate for the AGN photo-ionization rate at z ∼ 5.5 is in agreement with the observed values at similar redshifts, which are needed to keep the intergalactic medium highly ionized. Upcoming JWST and giant ground based telescopes observations will improve the study of high-z AGNs and their contribution to the reionization of the Universe.

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Section: The Ionizing Background At Z > 5 and Implications On Reioniz...mentioning

confidence: 99%

On the AGN nature of two UV bright sources at z_spec~5.5 in the CANDELS fields: an update of the AGN space density at M1450~-22.5

Grazian,

Giallongo,

Fiore

et al. 2020

Preprint

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“…Evidence has been posed both for (e.g. 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.…”

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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“…Understanding the mechanisms responsible for the launch and emission of these jets is of crucial importance for constraining the kinetic power they carry and therefore their feedback on the intergalactic medium as a function of redshift (e.g., Nesvadba et al 2007;Fabian 2012). It is also crucial for constraining the cosmological evolution of the SMBHs hosted in jetted AGNs (e.g., Fabian et al 2014) and the relative contribution of jets to the re-ionisation of the Universe at z > 6 (e.g., Torres-Albà et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Direct observation of an extended X-ray jet at z = 6.1

Ighina

Moretti

Tavecchio

et al. 2022

A&A

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We report on the direct observation of an extended X-ray jet in the z = 6.1 radio-loud active galactic nucleus PSO J030947.49+271757.31 from a deep Chandra X-ray observation (128 ksec). This detection represents the most distant kiloparsec-scale off-nuclear emission resolved in X-rays to date. The angular distance of the emission is ∼4″ (corresponding to ∼20 kpc at z = 6.1), along the same direction of the jet observed at parsec scales in previous VLBA high-resolution radio observations. Moreover, the 0.5–7.0 keV isophotes coincide with the extended radio emission as imaged by the VLA Sky Survey at 3 GHz. The rest-frame 2–10 keV luminosity of the extended component is L2 − 10 keV = 5.9 × 1044 erg s−1, about 8% of the core: this makes it one of the most luminous jets resolved in X-rays so far. Through spectral energy distribution modelling we find that this emission can be explained by the inverse Compton interaction with the photons of the cosmic microwave background, assuming that the jet’s physical parameters are similar to those in the local Universe. At the same time, we find that the radiation produced by a putative population of high-energy electrons through the synchrotron process observed at low redshift is quenched at high redshift, hence becoming negligible.

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AGN jets versus accretion as reionization sources

Cited by 9 publications

References 61 publications

On the AGN nature of two UV bright sources at z_spec~5.5 in the CANDELS fields: an update of the AGN space density at M1450~-22.5

On the AGN nature of two UV bright sources at z_spec~5.5 in the CANDELS fields: an update of the AGN space density at M1450~-22.5

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

Direct observation of an extended X-ray jet at z = 6.1

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