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The THESAN project: predictions for multitracer line intensity mapping in the epoch of reionization

Kannan, Rahul and Smith, Aaron and Garaldi, Enrico and Shen, Xuejian and Vogelsberger, Mark and Pakmor, Rüdiger and Springel, Volker and Hernquist, Lars (2022) The THESAN project: predictions for multitracer line intensity mapping in the epoch of reionization. Monthly Notices of the Royal Astronomical Society, 514 (3). pp. 3857-3878. ISSN 0035-8711. doi:10.1093/mnras/stac1557.

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Line intensity mapping (LIM) is rapidly emerging as a powerful technique to study galaxy formation and cosmology in the high-redshift Universe. We present LIM estimates of select spectral lines originating from the interstellar medium (ISM) of galaxies and 21 cm emission from neutral hydrogen gas in the Universe using the large volume, high resolution thesan reionization simulations. A combination of subresolution photoionization modelling for H ii regions and Monte Carlo radiative transfer calculations is employed to estimate the dust-attenuated spectral energy distributions (SEDs) of high-redshift galaxies (z ≳ 5.5). We show that the derived photometric properties such as the ultraviolet (UV) luminosity function and the UV continuum slopes match observationally inferred values, demonstrating the accuracy of the SED modelling. We provide fits to the luminosity–star formation rate relation (L–SFR) for the brightest emission lines and find that important differences exist between the derived scaling relations and the widely used low-z ones because the ISM of reionization era galaxies is generally less metal enriched than in their low-redshift counterparts. We use these relations to construct line intensity maps of nebular emission lines and cross-correlate with the 21 cm emission. Interestingly, the wavenumber at which the correlation switches sign (k_(transition)) depends heavily on the reionization model and to a lesser extent on the targeted emission line, which is consistent with the picture that k_(transition) probes the typical sizes of ionized regions. The derived scaling relations and intensity maps represent a timely state-of-the-art framework for forecasting and interpreting results from current and upcoming LIM experiments.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Kannan, Rahul0000-0001-6092-2187
Smith, Aaron0000-0002-2838-9033
Garaldi, Enrico0000-0002-6021-7020
Shen, Xuejian0000-0002-6196-823X
Vogelsberger, Mark0000-0001-8593-7692
Pakmor, Rüdiger0000-0003-3308-2420
Springel, Volker0000-0001-5976-4599
Hernquist, Lars0000-0001-6950-1629
Alternate Title:The THESAN project: predictions for multi-tracer line intensity mapping in the Epoch of Reionization
Additional Information:© 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Received: 08 November 2021. Revision received: 31 May 2022. Accepted: 01 June 2022. Published: 09 June 2022. We thank the anonymous referee for constructive comments that helped improve the paper. We also thank Angus Beane for insightful discussions related to this work. AS acknowledges support for Program number HST-HF2-51421.001-A provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, incorporated, under NASA contract NAS5-26555. MV acknowledges support through NASA ATP grants 16-ATP16-0167, 19-ATP19-0019, 19-ATP19-0020, 19-ATP19-0167, and NSF grants AST-1814053, AST-1814259, AST-1909831, and AST-2007355. The authors gratefully acknowledge the Gauss Centre for Supercomputing e.V. ( for funding this project by providing computing time on the GCS Supercomputer SuperMUC-NG at Leibniz Supercomputing Centre ( Additional computing resources were provided by the Extreme Science and Engineering Discovery Environment (XSEDE), at Stampede2 and Comet through allocation TG-AST200007 and by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center. DATA AVAILABILITY. All simulation data, including intrinsic and dust-attenuated galaxy SEDs, will be made publicly available in the near future. Data will be distributed via Before the public data release, data underlying this article will be shared on reasonable request to the corresponding author(s).
Funding AgencyGrant Number
NASA Hubble FellowshipHST-HF2-51421.001-A
Gauss Centre for SupercomputingUNSPECIFIED
Subject Keywords:galaxies: high-redshift, intergalactic medium, (cosmology:) dark ages, reionization, first stars, (cosmology:) diffuse radiation, (cosmology:) large-scale structure of Universe
Issue or Number:3
Record Number:CaltechAUTHORS:20220802-742122000
Persistent URL:
Official Citation:Rahul Kannan, Aaron Smith, Enrico Garaldi, Xuejian Shen, Mark Vogelsberger, Rüdiger Pakmor, Volker Springel, Lars Hernquist, The THESAN project: predictions for multitracer line intensity mapping in the epoch of reionization, Monthly Notices of the Royal Astronomical Society, Volume 514, Issue 3, August 2022, Pages 3857–3878,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:116009
Deposited By: George Porter
Deposited On:03 Aug 2022 14:06
Last Modified:03 Aug 2022 14:06

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