CMB quenching of high-redshift radio-loud AGNs

Ghisellini, G.; Haardt, Francesco; Ciardi, B.; Sbarrato, T.; Gallo, Elena; Tavecchio, F.; Celotti, A.

doi:10.1093/mnras/stv1541

Cited by 41 publications

(49 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In all of our models, the global signal is heavily impacted only when the ratio between radio and bolometric luminosity is similar to low redshift. As recognized in previous works (Ghisellini et al 2014(Ghisellini et al , 2015Saxena et al 2017), this cannot be the case for classical FRII lobes where magnetic fields tend to be below 100µG. More recently, S18 showed that regions where magnetic fields are below 1000µG would not produce appreciable SE due to IC scattering.…”

Section: Is Inverse Compton Cooling a Showstopper?mentioning

confidence: 80%

“…It has long been recognized that the diffuse lobes, that dominate radio emission in many low-redshift active galactic nuclei (AGN), should be suppressed at high redshift. The higher energy density of the Cosmic Microwave Background (CMB) is expected to cause relativistic electrons to shed their energy through inverse Compton (IC) scattering instead of synchrotron emission (SE) (e.g., Ghisellini et al 2014Ghisellini et al , 2015Saxena et al 2017). IC suppression of SE may partially explain the dearth of SDSS quasars matched with radio sources at z 3 (Haiman et al 2004;McGreer et al 2009;Volonteri et al 2011).…”

Section: ; Mcquinn 2016))mentioning

confidence: 99%

See 1 more Smart Citation

The Radio Scream from black holes at Cosmic Dawn: a semi-analytic model for the impact of radio-loud black holes on the 21 cm global signal

Ewall‐Wice

Chang

Lazio

2019

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We use a semi-analytic model to explore the potential impact of a brief and violent period of radio-loud accretion on to black holes (The Radio Scream) during the Cosmic Dawn on the H i hyperfine 21 cm signal. We find that radio emission from supermassive black hole seeds can impact the global 21 cm signal at the level of tens to hundreds of per cent provided that they were as radio loud as $z$ ≈ 1 black holes and obscured by gas with column depths of NH ≳ 1023 cm−2. We determine plausible sets of parameters that reproduce some of the striking features of the EDGES absorption feature including its depth, timing, and side steepness while producing radio/X-ray backgrounds and source counts that are consistent with published limits. Scenarios yielding a dramatic 21 cm signature also predict large populations of ∼$\mu$Jy point sources that will be detectable in future deep surveys from the Square Kilometer Array (SKA). Thus, 21 cm measurements, complemented by deep point-source surveys, have the potential to constrain optimistic scenarios where supermassive black hole progenitors were radio loud.

show abstract

Section: Is Inverse Compton Cooling a Showstopper?mentioning

confidence: 80%

Section: ; Mcquinn 2016))mentioning

confidence: 99%

The Radio Scream from black holes at Cosmic Dawn: a semi-analytic model for the impact of radio-loud black holes on the 21 cm global signal

Ewall‐Wice

Chang

Lazio

2019

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…This value is within the range of what one would expect for synchrotron emitted by shock injected electrons, such as what is observed in the lobes and hot-spots of low-redshift radio sources. However, diffuse lobe emission may be difficult to produce at high redshifts due to enhanced Compton cooling from CMB photons (Ghisellini et al 2014(Ghisellini et al , 2015Saxena et al 2017). Sharma (2018) notes that the short cooling times at high redshift would lead to spectral aging and an index closer to ≈ −1.1.…”

Section: Radio Emissionmentioning

confidence: 99%

Modeling the Radio Background from the First Black Holes at Cosmic Dawn: Implications for the 21 cm Absorption Amplitude

Ewall‐Wice

Chang

Lazio

et al. 2018

ApJ

231

176

View full text Add to dashboard Cite

We estimate the 21 cm Radio Background from accretion onto the first intermediate-mass Black Holes between z ≈ 30 and z ≈ 16. Combining potentially optimistic, but plausible, scenarios for black hole formation and growth with empirical correlations between luminosity and radio-emission observed in low-redshift active galactic nuclei, we find that a model of black holes forming in molecular cooling halos is able to produce a 21 cm background that exceeds the Cosmic Microwave Background (CMB) at z ≈ 17 though models involving larger halo masses are not entirely excluded. Such a background could explain the surprisingly large amplitude of the 21 cm absorption feature recently reported by the EDGES collaboration. Such black holes would also produce significant X-ray emission and contribute to the 0.5−2 keV soft X-ray background at the level of ≈ 10 −13 −10 −12 erg sec −1 cm −2 deg −2 , consistent with existing constraints. In order to avoid heating the IGM over the EDGES trough, these black holes would need to be obscured by Hydrogen column depths of N H ∼ 5 × 10 23 cm −2 . Such black holes would avoid violating contraints on the CMB optical depth from Planck if their UV photon escape fractions were below f esc 0.1, which would be a natural result of N H ∼ 5 × 10 23 cm −2 imposed by an unheated IGM.

show abstract

“…The jet deposits its power into the hotspots through a termination shock, which in turn energizes the more extended lobes. To model the radiation produced in the hotspots we follow the prescriptions detailed in Ghisellini et al (2015). The particle injection function obeys Eq.…”

Section: Hotspot Emissionmentioning

confidence: 99%

“…We establish robust, conservative criteria to isolate a subset of objects with statistically significant, extended X-ray emission ( §2). For those, we decompose the X-ray emission into core and extended (lobes+hotspots) components, and model the resulting broadband SEDs following Ghisellini et al (2015), accounting for both CMB as well as IR emission from the host galaxy as possible Comptonization seed photons ( §3). We summarize and discuss our results in §4.…”

Section: Introductionmentioning

confidence: 99%

CMB-induced radio quenching of high-redshift jetted AGNs with highly magnetic hotspots

Ghisellini

Hodges-Kluck

et al. 2017

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

In an effort to understand the cause of the apparent depletion in the number density of radio-loud AGNs at z > 3, this work investigates the viability of the so-called Cosmic Microwave Background (CMB) quenching mechanism of intrinsically jetted, high-z AGNs, whereby Inverse Compton scattering of CMB photons off electrons within the extended lobes results in a substantial dimming of the lobe synchrotron emission at GHz frequencies, while simultaneously boosting their diffuse X-ray signal. We focus on five z > 3.5 radio galaxies that have sufficiently deep Chandra exposure (> 50 ks) to warrant a meaningful investigation of any extended X-ray emission. For those objects with evidence for statistically significant extended X-ray lobes (4C 41.17 and 4C 03.24), we combine the Chandra measurements with literature data at lower frequencies to assemble the systems' Spectral Energy Distributions (SEDs), and utilize state-of-the-art SED modelling (Ghisellini et al. 2015) -including emission from the disk, torus, jet, hotspots, and lobes -to infer their physical parameters. For both radio galaxies, the magnetic energy density in the hotspots is found to exceed the energy density in CMB photons, wheres the opposite is true for the lobes. This implies that any extended synchrotron emission likely originates from the hotspots themselves, rather than the lobes. Conversely, Inverse Compton scattering of CMB photons dominates the extended X-ray emission from the lobes, which are effectively "radio-quenched". As a result, CMB quenching is effective in these systems in spite of the fact that the observed X-ray to radio luminosity ratio does not bear the signature (1 + z) 4 dependence of the CMB energy density.

show abstract

CMB quenching of high-redshift radio-loud AGNs

Cited by 41 publications

References 57 publications

The Radio Scream from black holes at Cosmic Dawn: a semi-analytic model for the impact of radio-loud black holes on the 21 cm global signal

The Radio Scream from black holes at Cosmic Dawn: a semi-analytic model for the impact of radio-loud black holes on the 21 cm global signal

Modeling the Radio Background from the First Black Holes at Cosmic Dawn: Implications for the 21 cm Absorption Amplitude

CMB-induced radio quenching of high-redshift jetted AGNs with highly magnetic hotspots

Contact Info

Product

Resources

About