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Spectral Variations of the Sky: Constraints on Alternate Universes

Chary, R. (2016) Spectral Variations of the Sky: Constraints on Alternate Universes. Astrophysical Journal, 817 (1). p. 33. ISSN 0004-637X.

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The fine tuning of parameters required to reproduce our present day universe suggests that our universe may simply be a region within an eternally inflating super-region. Many other regions beyond our observable universe would exist with each such region governed by a different set of physical parameters. Collision between these regions, if they occur, should leave signatures of anisotropy in the cosmic microwave background (CMB) but have not been seen. We analyze the spectral properties of masked, foreground-cleaned maps between 100 and 545 GHz constructed from the Planck data set. Four distinct ~2°–4° regions associated with CMB cold spots show anomalously strong 143 GHz emission but no correspondingly strong emission at either 100 or 217 GHz. The signal to noise of this 143 GHz residual emission is at the ≳6σ level which reduces to 3.2–5.4σ after subtraction of remaining synchrotron/free–free foregrounds. We assess different mechanisms for this residual emission and conclude that although there is a 30% probability that noise fluctuations may cause foregrounds to fall within 3σ of the excess, there is less than a 0.5% probability that foregrounds can explain all the excess. A plausible explanation is that the collision of our universe with an alternate universe whose baryon to photon ratio is a factor of ~4500 larger than ours, could produce enhanced hydrogen Paschen-series emission at the epoch of recombination. Future spectral mapping and deeper observations at 100 and 217 GHz are needed to mitigate systematics arising from unknown Galactic foregrounds and to confirm this unusual hypothesis.

Item Type:Article
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URLURL TypeDescription Paper
Chary, R.0000-0001-7583-0621
Additional Information:© 2016 The American Astronomical Society. Received 2015 September 2; accepted 2015 November 25; published 2016 January 20. Planck ( is a project of the European Space Agency (ESA) with instruments provided by two scientific consortia funded by ESA member states and led by Principal Investigators from France and Italy, telescope reflectors provided through a collaboration between ESA and a scientific consortium led and funded by Denmark, and additional contributions from NASA (USA). High quality data products have been generated through extensive work by the HFI Core Team lead by J.-L. Puget and the Planck Collaboration as a whole. The author wishes to thanks A. Banday, G. Helou, M. Kleban, E. Wright, J. Chluba and J. Carpenter for feedback and discussions and G. Fazio and J. Robie for their hospitality. This work has made use of NASA's Infrared Science Archive.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
European Space Agency (ESA)UNSPECIFIED
Subject Keywords:cosmic background radiation – cosmology: observations – diffuse radiation – surveys
Issue or Number:1
Record Number:CaltechAUTHORS:20160303-140729155
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Official Citation:R. Chary 2016 ApJ 817 33
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:65031
Deposited By: Tony Diaz
Deposited On:04 Mar 2016 20:45
Last Modified:03 Oct 2019 09:43

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