Critical Star Formation Rates for Reionization: Full Reionization Occurs at Redshift z ≈ 7

Details Critical Star Formation Rates for Reionization: Full Reionization Occurs at Redshift z ≈ 7 Critical Star Formation Rates for Reionization: Full Reionization Occurs at Redshift z ≈ 7

Mar 2012

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012apj...747..100s&link_type=abstract

The Astrophysical Journal, Volume 747, Issue 2, article id. 100 (2012).

Astronomy and Astrophysics

Astronomy

3

Dark Ages, Reionization, First Stars, Galaxies: High-Redshift, Intergalactic Medium

Scientific paper

We assess the probable redshift (z rei ≈ 7) for full reionization of the intergalactic medium (IGM) using a prescription for the comoving star formation rate (SFR) density (\dot{\rho }_SFR) required to maintain photoionization against recombination. Our newly developed online reionization simulator allows users to assess the required SFR and ionization histories, using a variety of assumptions for galactic and stellar populations, IGM clumping factor and temperature, and Lyman continuum (LyC) escape fraction. The decline in high-redshift galaxy candidates and Lyα emitters at z = 6-8 suggests a rising neutral fraction, with reionization at z >~ 7 increasingly difficult owing to increased recombination rates and constraints from the ionizing background and LyC mean free path. The required rate is \dot{\rho }_SFR \approx (0.018 \, M_{\odot } \,yr^{-1}\, Mpc^{-3})[(1+z)/8]^3 (C_{H}/3)(0.2/f_esc) T_4^{-0.845} scaled to fiducial values of clumping factor C H = 3, escape fraction f esc = 0.2, electron temperature Te = 104 K, and low-metallicity initial mass functions (IMFs) and stellar atmospheres. Our hydrodynamical + N-body simulations find a mean clumping factor C H ≈ (2.9)[(1 + z)/6]-1.1 in the photoionized, photoheated filaments at z = 5-9. The critical SFR could be reduced by increasing the minimum stellar mass, invoking a top-heavy IMF, or systematically increasing f esc at high z. The cosmic microwave background optical depth, τ e = 0.088 ± 0.015, could be explained by full reionization, producing τ e = 0.050 back to z rei ≈ 7, augmented by Δτ e ≈ 0.01-0.04 in a partially ionized IGM at z > 7. In this scenario, the strongest 21 cm signal should occur at redshifted frequencies 124-167 MHz owing to IGM heating over an interval Δz ≈ 3 in the range z ≈ 7.5-10.5.

Affiliated with

Also associated with

No associations

Rating

Critical Star Formation Rates for Reionization: Full Reionization Occurs at Redshift z ≈ 7 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Critical Star Formation Rates for Reionization: Full Reionization Occurs at Redshift z ≈ 7, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Critical Star Formation Rates for Reionization: Full Reionization Occurs at Redshift z ≈ 7 will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1365255