Universität zu Köln

Riechers, Dominik A., Weiss, Axel, Walter, Fabian, Carilli, Christopher L., Cox, Pierre, Decarli, Roberto and Neri, Roberto (2022). Microwave background temperature at a redshift of 6.34 from H2O absorption. Nature, 602 (7895). S. 58 - 70. BERLIN: NATURE PORTFOLIO. ISSN 1476-4687

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Abstract

Distortions of the observed cosmic microwave background provide a direct measurement of the microwave background temperature at redshifts from 0 to 1 (refs.(1,2)). Some additional background temperature estimates exist at redshifts from 1.8 to 3.3 based on molecular and atomic line-excitation temperatures in quasar absorption-line systems, but are model dependent(3). No deviations from the expected (1 + z) scaling behaviour of the microwave background temperature have been seen4, but the measurements have not extended deeply into the matter-dominated era of the Universe at redshifts z > 3.3. Here we report observations of submillimetre line absorption from the water molecule against the cosmic microwave background at z = 6.34 in a massive starburst galaxy, corresponding to a lookback time of 12.8 billion years (ref.(5)). Radiative pumping of the upper level of the ground-state ortho-H2O(1(10)-1(01)) line due to starburst activity in the dusty galaxy HFLS3 results in a cooling to below the redshifted microwave background temperature, after the transition is initially excited by the microwave background. This implies a microwave background temperature of 16.4-30.2 K (1 sigma range) at z = 6.34, which is consistent with a background temperature increase with redshift as expected from the standard Lambda CDM cosmology(4).

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Riechers, Dominik A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Weiss, Axel UNSPECIFIED UNSPECIFIED UNSPECIFIED Walter, Fabian UNSPECIFIED UNSPECIFIED UNSPECIFIED Carilli, Christopher L. UNSPECIFIED UNSPECIFIED UNSPECIFIED Cox, Pierre UNSPECIFIED UNSPECIFIED UNSPECIFIED Decarli, Roberto UNSPECIFIED UNSPECIFIED UNSPECIFIED Neri, Roberto UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-690016
DOI:	10.1038/s41586-021-04294-5
Journal or Publication Title:	Nature
Volume:	602
Number:	7895
Page Range:	S. 58 - 70
Date:	2022
Publisher:	NATURE PORTFOLIO
Place of Publication:	BERLIN
ISSN:	1476-4687
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language RADIATION TEMPERATURE; MOLECULAR-HYDROGEN; STARBURST GALAXY; CO; EXCITATION; LINES; DUST; GAS Multiple languages Multidisciplinary Sciences Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/69001