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| ID:
742630.0,
MPI für Astronomie / Publikationen_mpia |
| The thermal proximity effect: A new probe of the He II reionization history and quasar lifetime |
| Authors: | Khrykin, I. S.; Hennawi, J. F.; McQuinn, M. | | Date of Publication (YYYY-MM-DD): | 2017 | | Title of Journal: | The Astrophysical Journal | | Volume: | 838 | | Issue / Number: | 2 | | Start Page: | id. 96 (22 pp) | | Audience: | Not Specified | | Abstract / Description: | Despite decades of effort, the timing and duration of He ii reionization and the properties of the quasars believed to drive it are still not well constrained. We present a new method to study both via the thermal proximity effect—the heating of the intergalactic medium (IGM) around quasars when their radiation doubly ionizes helium. We post-process hydrodynamical simulations with 1D radiative transfer and study how the thermal proximity effect depends on the He ii fraction, {x}{He{{II}},0}, which prevailed in the IGM before the quasar turned on, and the quasar lifetime {t}{{Q}}. We find that the amplitude of the temperature boost in the quasar environment depends on {x}{He{{II}},0}, with a characteristic value of {{Δ }}T≃ {10}4 {{K}} for {x}{He{{II}},0}=1.0, whereas the size of the thermal proximity zone is sensitive to {t}{{Q}}, with typical sizes of ≃ 100 {cMpc} for {t}{{Q}}={10}8 {yr}. This temperature boost increases the thermal broadening of H i absorption lines near the quasar. We introduce a new Bayesian statistical method based on measuring the Lyα forest power spectrum as a function of distance from the quasar, and demonstrate that the thermal proximity effect should be easily detectable. For a mock data set of 50 quasars at z≃ 4, we predict that one can measure {x}{He{{II}},0} to an (absolute) precision ≈ 0.04 and {t}{{Q}} to a precision of ≈ 0.1 dex. By applying our formalism to existing high-resolution Lyα forest spectra, one should be able to reconstruct the He ii reionization history, providing a global census of hard photons in the high-z universe. | | Free Keywords: | cosmology: theory; dark ages; reionization; first stars; intergalactic medium; quasars: general | | External Publication Status: | published | | Document Type: | Article |
| Communicated by: | N. N. | | Affiliations: | MPI für Astronomie | | Identifiers: | ISSN:0004-637X %R 10.3847/1538-4357/aa6621
URL:http://adsabs.harvard.edu/abs/2017ApJ...838...96K
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