2003/09/12 by N. M. Forster Schreiber, N. M. Förster Schreiber, R. Genzel +2 · 5 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/379097
published as Astrophys.J.599:193-217,2003 · 48 pages, incl. 16 Postscript figures; accepted for publication in the Astrophysical Journal
arxiv created 2003/09/12 · openalex publication_date 2003/12/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/01
We present new evolutionary synthesis models of M82 based mainly on observations consisting of near-infrared integral field spectroscopy and mid-infrared spectroscopy. The models incorporate stellar evolution, spectral synthesis, and photoionization modeling and are optimized forλ = 1-45 μm observations of starburst galaxies. The data allow us to model the starburst regions on scales as small as 25 pc. We investigate the initial mass function (IMF) of the stars and constrain quantitatively the spatial and temporal evolution of starburst activity in M82. We find a typical decay timescale for individual burst sites of a few million years. The data are consistent with the formation of very massive stars (≳50-100 M ☉ ) and require a flattening of the starburst IMF below a few solar masses, assuming a Salpeter slope dN / dm ∝ m -2.35 at higher masses. Our results are well matched by a scenario in which the global starburst activity in M82 occurred in two successive episodes each lasting a few million years, peaking about 10 7 yr and 5 × 10 6 yr ago. The first episode took place throughout the central regions of M82 and was particularly intense at the nucleus, while the second episode occurred predominantly in a circumnuclear ring and along the stellar bar. We interpret this sequence as resulting from the gravitational interaction between M82 and its neighbor M81, and subsequent bar-driven evolution. The short burst duration on all spatial scales indicates strong negative feedback effects of starburst activity, both locally and globally. Simple energetics considerations suggest that the collective mechanical energy released by massive stars was able to rapidly inhibit star formation after the onset of each episode.