A Caltech Library Service

Resolving the H i in damped Lyman α systems that power star formation

Bordoloi, Rongmon and O’Meara, John M. and Sharon, Keren and Rigby, Jane R. and Cooke, Jeff and Shaban, Ahmed and Matuszewski, Mateusz and Rizzi, Luca and Doppmann, Greg and Martin, D. Christopher and Moore, Anna M. and Morrissey, Patrick and Neill, James D. (2022) Resolving the H i in damped Lyman α systems that power star formation. Nature, 606 (7912). pp. 59-63. ISSN 0028-0836. doi:10.1038/s41586-022-04616-1.

[img] PDF - Accepted Version
See Usage Policy.

Image (JPEG) (Extended Data Fig. 1: Source plane reconstruction of SGAS J152745.1+065219) - Supplemental Material
See Usage Policy.

Image (JPEG) (Extended Data Fig. 2: Pairwise H I column density variation versus physical separation) - Supplemental Material
See Usage Policy.

Image (JPEG) (Extended Data Fig. 3: Variation in metal absorption line strengths of the two DLA systems) - Supplemental Material
See Usage Policy.

Image (JPEG) (Extended Data Fig. 4: Spatial variation of neutral hydrogen column density of the z ≈ 2.05 DLA) - Supplemental Material
See Usage Policy.

Image (JPEG) (Extended Data Table 1 Absorption line measurements for the z = 2.54290 DLA) - Supplemental Material
See Usage Policy.

Image (JPEG) (Extended Data Table 2 Absorption line measurements for the z = 2.05601 DLA) - Supplemental Material
See Usage Policy.


Use this Persistent URL to link to this item:


Reservoirs of dense atomic gas (primarily hydrogen) contain approximately 90 per cent of the neutral gas at a redshift of 3, and contribute to between 2 and 3 per cent of the total baryons in the Universe. These ‘damped Lyman α systems’—so called because they absorb Lyman α photons within and from background sources—have been studied for decades, but only through absorption lines present in the spectra of background quasars and γ-ray bursts. Such pencil beams do not constrain the physical extent of the systems. Here we report integral-field spectroscopy of a bright, gravitationally lensed galaxy at a redshift of 2.7 with two foreground damped Lyman α systems. These systems are greater than 238 kiloparsecs squared in extent, with column densities of neutral hydrogen varying by more than an order of magnitude on scales of less than 3 kiloparsecs. The mean column densities are between 10^(20.46) and 10^(20.84) centimetres squared and the total masses are greater than 5.5 × 10⁸–1.4 × 10⁹ times the mass of the Sun, showing that they contain the necessary fuel for the next generation of star formation, consistent with relatively massive, low-luminosity primeval galaxies at redshifts greater than 2.

Item Type:Article
Related URLs:
URLURL TypeDescription ReadCube access Paper ItemKeck Observatory Archive package package package
Bordoloi, Rongmon0000-0002-3120-7173
O’Meara, John M.0000-0002-7893-1054
Sharon, Keren0000-0002-7559-0864
Rigby, Jane R.0000-0002-7627-6551
Cooke, Jeff0000-0001-5703-2108
Shaban, Ahmed0000-0002-8858-7875
Matuszewski, Mateusz0000-0003-2821-1750
Rizzi, Luca0000-0003-0882-2327
Martin, D. Christopher0000-0002-8650-1644
Moore, Anna M.0000-0002-2894-6936
Morrissey, Patrick0000-0001-8177-1023
Neill, James D.0000-0002-0466-1119
Additional Information:© 2022 Springer Nature Limited. Received 18 August 2021. Accepted 04 March 2022. Published 18 May 2022. This work was supported by a NASA Keck PI Data Award, administered by the NASA Exoplanet Science Institute. Data presented herein were obtained at the W. M. Keck Observatory from telescope time allocated to the National Aeronautics and Space Administration (NASA) through the agency’s scientific partnership with the California Institute of Technology and the University of California. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. This research was conducted, in part, by the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013. We wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. This research made use of Montage. It is funded by the National Science Foundation under grant number ACI-1440620, and was previously funded by the NASA’s Earth Science Technology Office, Computation Technologies Project, under cooperative agreement number NCC5-626 between NASA and the California Institute of Technology. Data availability. Data that support the findings of this study are publicly available at the Keck Observatory Archive,, under project codes N083 and K338 and the Barbara A. Mikulski Archive for Space Telescope under project code GO-13003. Fully reduced data are available from the corresponding author upon request. Code availability. All codes used in this work are publicly available. The H I column density measurements were performed using the linetools package ( Reduction and analysis of the KCWI data cubes were done using the kcwitools package ( The lensing raytracing and absorption line measurements are done using the rbcodes package ( HST image analysis and lens modelling were performed with AstroDizzle software and Lenstool, respectively. Contributions. R.B. and J.M.O. developed the idea for the project, wrote the NASA/Keck telescope proposal and designed and performed the observations. R.B. developed the analysis tools, performed the analysis, devised original ways to interpret the results and authored majority of the text. J.M.O. reduced the KCWI data. A.S. performed the metal absorption line measurements. K.S. performed the lens model and provided Extended Data Fig. 1. J.R.R. provided the ancillary data from MagE and metal absorber information from MagE spectra. J.C., J.M.O. and R.B. provided steps to correct astrometric offsets and J.C. confirmed the redshift of the second DLA, and contributed to the interpretations. M.M., L.R., G.D., D.C.M., A.M.M., P.M. and J.D.N. developed the KCWI data reduction pipeline and built and delivered the instrument when initial commissioning data provided the data needed to verify the target as an object of interest. All authors, including J.M.O., J.R.R. and J.C., contributed to the overall interpretation of the results and various aspects of the analysis and writing. The authors declare no competing interests. Peer review information. Nature thanks Zachary Hafen and Marcel Neeleman for their contribution to the peer review of this work.
Group:Astronomy Department, Space Astrophysics Laboratory
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
Australian Research CouncilCE170100013
Issue or Number:7912
Record Number:CaltechAUTHORS:20220519-375159000
Persistent URL:
Official Citation:Bordoloi, R., O’Meara, J.M., Sharon, K. et al. Resolving the H I in damped Lyman α systems that power star formation. Nature 606, 59–63 (2022).
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:114811
Deposited By: George Porter
Deposited On:19 May 2022 21:17
Last Modified:07 Jun 2022 21:48

Repository Staff Only: item control page