1. Taking the Universe's Temperature with Spectral Distortions of the Cosmic Microwave Background.
- Author
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Hill, J. Colin, Battaglia, Nick, Chluba, Jens, Ferraro, Simone, Schaan, Emmanuel, and Spergel, David N.
- Subjects
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COSMIC background radiation , *COMPTON scattering , *SUNYAEV-Zel'dovich effect , *ATMOSPHERIC temperature , *SIGNAL-to-noise ratio , *ASTROPHYSICAL radiation - Abstract
The cosmic microwave background (CMB) energy spectrum is a near-perfect blackbody. The standard model of cosmology predicts small spectral distortions to this form, but no such distortion of the skyaveraged CMB spectrum has yet been measured. We calculate the largest expected distortion, which arises from the inverse Compton scattering of CMB photons off hot, free electrons, known as the thermal Sunyaev-Zel'dovich (TSZ) effect. We show that the predicted signal is roughly one order of magnitude below the current bound from the COBE-FIRAS experiment, but it can be detected at enormous significance (> 1 OOOcr) by the proposed Primordial Inflation Explorer (PIXIE). Although cosmic variance reduces the effective signal-to-noise ratio to 230er, this measurement will still yield a subpercent constraint on the total thermal energy of electrons in the observable Universe. Furthermore, we show that PIXIE can detect subtle relativistic effects in the sky-averaged TSZ signal at 30
- Published
- 2015
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