Year: 2026
Type: article
Abstract: We report the detection of a new 21 cm absorption system associated with the radio source NVSS J164725 + 375218 at a redshift of z = 2.327, identified through a pilot survey conducted by the Canadian Hydrogen Intensity Mapping Experiment (CHIME). This is the fifth detection of an associated system at z > 2. By analyzing a subset of available data, we conduct a spectrally blind survey for 21 cm absorption systems within the redshift range of 0.78–2.55 along 202 lines of sight toward known sources in the declination range of 35° to 60°. We detect three 21 cm absorbers: two previously known intervening systems and one newly discovered associated system. By fitting the absorption profiles with models containing one to three Gaussian components and selecting the best model using the Bayesian information criterion, we estimate the optical depth, velocity-integrated optical depth, and the ratio between the H i column density and the spin temperature of the absorption systems. These results demonstrate CHIME’s ability to discover new absorbers, even in a small subset of its full dataset.
Source: The Astrophysical Journal
Authors: Mandana Amiri, Arnab Chakraborty, Simon Foreman, Mark Halpern, Alex S. Hill, Gary Hinshaw, Carolin Höfer, Albin Joseph, Joshua MacEachern, Kiyoshi W. Masui, Juan Mena-Parra, Arash Mirhosseini, Ue-Li Pen, Tristan Pinsonneault-Marotte, Alex Reda, J. Richard Shaw, Seth R. Siegel, Yukari Uchibori, Rik van Lieshout, Haochen Wang, Dallas Wulf
Institutions: University of British Columbia, McGill University, Arizona State University, Herzberg Institute of Astrophysics, National Research Council Canada, University of British Columbia, Okanagan Campus, University of Groningen, Massachusetts Institute of Technology, University of Toronto, Institute of Astronomy and Astrophysics, Academia Sinica, Perimeter Institute, Canadian Institute for Theoretical Astrophysics, SLAC National Accelerator Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Yale University, Trottier Space Institute at McGill, Netherlands Institute for Radio Astronomy
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
Funders: Canadian Institute for Advanced Research, McGill University, Canada Foundation for Innovation, University of Toronto, Alliance de recherche numérique du Canada, Smithsonian Astrophysical Observatory, Natural Sciences and Engineering Research Council of Canada, National Research Council Canada
Awards: G5745801876, G5860995584
OpenAlex ID: W7130420321