The Messenger Astronomical Science

ALMA Constrains the Stellar Initial Mass Function of Dusty Starburst Galaxies

Authors
  • Zhang, Zhi-Yu [ESO; Institute for Astronomy, University of Edinburgh, Royal Observatory Edinburgh, UK]
  • Romano, Donatella [INAF–Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Italy]
  • Ivison, Rob J. [European Southern Observatory (ESO); Institute for Astronomy, University of Edinburgh, Royal Observatory Edinburgh, UK]
  • Papadopoulos, Padelis P. [Department of Physics, Aristotle University of Thessaloniki, Greece; Research Center for Astronomy, Academy of Athens, Greece]
  • Matteucci, Francesca [Department of Physics, University of Trieste, Italy; INAF–Osservatorio Astronomico di Trieste, Italy; INFN, Sezione di Trieste, Italy]

Section
Astronomical Science
Abstract

The stellar initial mass function (IMF) is fundamental to all measurements of cosmic star formation, which involves an extrapolation from rare, massive stars (M∗ > 8 M) to the full stellar mass spectrum. Classical determinations of a galaxy’s IMF are limited to ultraviolet, optical and near-infrared wavelengths, and these cannot be adopted for dust- obscured galaxies with intense, ongoing star formation, even in the local Universe. The unprecedented sensi- tivity of the Atacama Large Millimeter/submillimeter Array (ALMA) allows us to detect weak emission from 13CO and C18O isotopologues, which offer a sensitive, relatively dust-free, probe of the IMF. Globally low 13CO/C18O ratios for all our targets — dusty starburst galaxies at redshifts ~ 2–3 — alongside a detailed chemical evolution model imply that stars formed in extreme starburst environments are significantly biased towards massive stars compared to ordinary star-forming spiral galaxies. We have combined information from the coldest interstellar medium (at tens of Kelvins) with the physics of nucleosynthesis in hot stars (at tens of millions of Kelvins), to delineate the formation and evolution of galaxies. This opens up a new window to probe the stellar IMF of galaxies with ALMA and it challenges our understanding of fundamental parameters governing galaxy formation and evolution, such as star formation rates, and the timescales for gas depletion and dust formation.


Dates
Created: 2018-06-01/2018-06-30
Length
4 pages

Cite this article:

Z. Zhang, D. Romano, R. Ivison, P. Papadopoulos, F. Matteucci; ALMA Constrains the Stellar Initial Mass Function of Dusty Starburst Galaxies. The Messenger 172 (June 2018): 14–17. https://doi.org/10.18727/0722-6691/5075