Year: 2024
Type: article
Abstract: Over the past decade, the relation between the Balmer-line luminosity of HII galaxies and the velocity width of the emission lines, the L − σ relation, has been painstakingly calibrated as a cosmological distance indicator with seemingly spectacular results: the Hubble constant and the energy density of dark energy obtained using the L − σ indicator agree remarkably well with the values from canonical indicators. Since most of the luminosity of these young compact starburst galaxies is emitted by a few narrow emission lines, they can be observed with good precision up to redshifts of z ∼ 7 with JWST, making the L − σ indicator a potentially unique cosmological probe. However, the precision of the method remains too low to effectively constrain the relevant cosmological parameters, notably the equation of state of dark energy. The scatter of the L − σ relation is significantly larger than the random observational errors, so we do not have a good handle on the systematics of the method. In a previous paper, we posited that since the ionizing radiation of these young galaxies fades rapidly over timescales of only a few million years, age differences could be the main underlying cause of the scatter. In this paper, we explore several different ways of explaining the scatter of the correlation, but without success. We show that the majority of HII galaxies are powered by multiple starbursts of slightly different ages, and therefore that the equivalent widths are not reliable chronometers to correct the luminosities for evolution. Thus, it is not likely that the accuracy of the L − σ distance indicator can be improved in the near future. Since we do not fully understand either the systematics or the underlying physics of the L − σ relation, using large samples of distant HII galaxies may or may not improve the accuracy of the method.
Source: Astronomy and Astrophysics
Authors: Jorge Melnick, Eduardo Telles
Institutions: National Observatory, European Southern Observatory
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,732
Funders: National Science Foundation, U.S. Department of Energy, National Aeronautics and Space Administration, Alfred P. Sloan Foundation, Princeton University, Ohio State University, California Institute of Technology, University of Washington, Johns Hopkins University, University of Pittsburgh, Case Western Reserve University, Drexel University, Universität Basel, University of Portsmouth, New Mexico State University, Chinese Academy of Sciences, Conselho Nacional de Desenvolvimento Científico e Tecnológico, Max-Planck-Gesellschaft, Max-Planck-Institut für Astronomie, Jet Propulsion Laboratory, University of California, Los Angeles, Ciência sem Fronteiras, U.S. Naval Observatory, Fermilab, Los Alamos National Laboratory
OpenAlex ID: W4401507252