Signatures of X-rays in the early Universe

By A. Mesinger, A. Ferrara, D. Spiegel. 2012

182 citations recorded by the source corpus.

[abridged] With their long mean free paths and efficient heating of the intergalactic medium (IGM), X-rays could have a dramatic impact on the thermal and ionization history of the Universe. We explore this in various signals: (i) Reionization history: including X-rays results in an earlier, more extended reionization. Efficient thermal feedback from X-ray heating could yield an extended, ~10% ionized epoch. (ii) Reionization morphology: a sizable (~10%) contribution of X-rays to reionization results in a more uniform morphology, though the impact is modest when compared at the same global neutral fraction, xH. However, changes in morphology cannot be countered by increasing the bias of the ionizing sources, making them a robust signature. (iii) The kinetic Sunyaev-Zel'dovich (kSZ) effect: at a fixed reionization history, X-rays decrease the kSZ power at l=3000 by ~0.5 microK^2. Our extreme model in which X-rays dominate reionization is the only one that is marginally consistent with upper limits from the South Pole Telescope, assuming no thermal Sunyaev-Zel'dovich (tSZ) - dusty galaxy correlation. Since this extreme model is unlikely, we conclude that there should be a sizable tSZ-dusty galaxy signal. (iv) The cosmic 21cm signal: the impact of X-rays on the 21cm power spectrum during the advanced stages of reionization (xH 0.9). This results in a 21cm power spectrum which is ~ 10-100 times higher than obtained from naive estimates ignoring this overlap. However, if thermal feedback is efficient, the resulting extended epoch between X-ray heating and reionization could provide a clean probe of the matter power spectrum in emission.

View Paper: https://www.semanticscholar.org/paper/d7bb4e5513a9b3e5c001cab91b45aa4b7023d214

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

1. M. McQuinn
2. B. Greig
3. Aaron Parsons
4. Jonathan C. Pober
5. A. Mesinger
6. Jaehong Park
7. M. Ouchi
8. R. Bouwens

Citations in the corpus

• Modeling the Radio Background from the First Black Holes at Cosmic Dawn: Implications for the 21 cm Absorption Amplitude (2018, background): “…of AGNs (Nandra & Pounds 1994; Reeves & Turner 2000; Page et al. 2005; Piconcelli et al. 2005), and a minimal X-ray energy of 0.5 keV due to self-absorption by the interstellar medium in each black hole’s host galaxy (Mesinger et al. 2013; Fialkov et al. 2014; Pacucci et al. 2014; Das et al. 2017).”
• Inferring the astrophysics of reionization and cosmic dawn from galaxy luminosity functions and the 21-cm signal (2018, background): “By heating the IGM prior to the bulk of reionization, Xrays are expected to play a dominant role during the CD (e.g. Pritchard & Furlanetto 2007; McQuinn & O’Leary 2012; Mesinger et al. 2013).”
• Hydrogen Epoch of Reionization Array (HERA) (2016, background): “The IGM is then expected to be heated by first generation X–ray binaries (Furlanetto 2006; Pritchard & Furlanetto 2007; Mesinger et al. 2013) or by the hot interstellar medium produced by the first supernovae (Pacucci et al. 2014), although the heating timing and magnitude is still very much…”
• PAPER-64 CONSTRAINTS ON REIONIZATION: THE 21 cm POWER SPECTRUM AT z = 8.4 (2015, background): “…al. 2008), their ultraviolet luminosities (McQuinn et al. 2007), the abundance of X-ray sources and other sources of heating (Pritchard & Loeb 2008; Mesinger et al. 2013), and higher-order cosmological effects like the relative velocities of baryons and dark matter (McQuinn & O’Leary 2012; Visbal…”
• Consistent modelling of the meta-galactic UV background and the thermal/ionization history of the intergalactic medium (2018, methodology): “We note that a similar approach has been recently proposed by Oñorbe et al. (2017) and more explicitly by Madau & Fragos (2017), based on an earlier work by Mesinger et al. (2013).”
• New Limits on 21cm EoR From PAPER-32 Consistent with an X-Ray Heated IGM at z=7.7 (2013, background): “Such constraints on Xray heating may soon have repercussions on the global signal (Pritchard & Loeb 2012) and on the morphology of ionization (Mesinger et al. 2013).”
• HUBBLE FRONTIER FIELDS FIRST COMPLETE CLUSTER DATA: FAINT GALAXIES AT z ∼ 5–10 FOR UV LUMINOSITY FUNCTIONS AND COSMIC REIONIZATION (2014, background): “X-ray sources such as X-ray binaries and faint AGNs would not leave a clear signature in the ρUV measurements, but provide a fraction of ionizing photons via X-ray necessary for the cosmic reionization (Fragos et al. 2013; Madau et al. 2004; Mesinger et al. 2013).”
• Inhomogeneous recombinations during cosmic reionization (2014, background): “During the second half of reionization, recombinations suppress the power spectra by ∼> 50–100% (RnF vs nRnF) on the k ∼ 0.1 Mpc −1 scales relevant for current 21cm interferometers (e.g. Pober et al. 2013; Mesinger et al. 2013).”
• Radiation Backgrounds at Cosmic Dawn: X-Rays from Compact Binaries (2016, methodology): “…when X-rays raise the gas temperature above that of the CMB (e.g., Madau et al. 1997; Venkatesan et al. 2001; Oh 2001; Madau et al. 2004; Ricotti & Ostriker 2004; Furlanetto 2006; Pritchard & Furlanetto 2007; Ciardi et al. 2010; Mirabel et al. 2011; Mesinger et al. 2011, 2013; Tanaka et al. 2016).”
• 21CMMC: an MCMC analysis tool enabling astrophysical parameter studies of the cosmic 21 cm signal (2015, methodology): “Reionization driven by relatively massive galaxies should result in larger, more uniform ionized regions (e.g. McQuinn et al. 2007; Iliev et al. 2012) and the large-scale PS should peak at the midpoint of the EoR (e.g. Lidz et al. 2008), unless reionization is driven by X-rays (Mesinger et al. 2013)”