The nature of starburst galaxies

Journal Article · Sun Dec 01 04:00:00 EST 1996 · Astrophysical Journal

DOI:https://doi.org/10.1086/178086· OSTI ID:501309

Lehnert, M D ^[1]; Heckman, T M ^[2]

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1. Institute of Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, 7000 East Avenue, L-413, Livermore, California 94550 (United States)
2. Rowland Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218 (United States)

Utilizing a large sample of infrared-selected starburst galaxies having optical images and long-slit spectra, we explore the interrelationships between the properties of starbursts and relate these properties to those of the {open_quotes}host{close_quotes} galaxy. We find that the half-light radius of the H{alpha}-emitting region ({ital r}{sub {ital e},H{alpha}}) enters into several correlations that suggest it is physically related to the actual starburst radius. Most suggestively, the effective IR surface brightness ({ital L}{sub IR}/{pi}{ital r}{sub {ital e},H{alpha}}{sup 2}) correlates strongly with the far-IR color temperature. This can be reproduced roughly with an idealized model of a surrounding dust screen whose far-IR emissivity is determined by the local energy density of UV starburst light. Typical values for {ital r}{sub {ital e},H{alpha}} are a few hundred pc to a few kpc (with the H{alpha} emission being significantly more compact than the red starlight). This confirms the {open_quotes}circumnuclear{close_quotes} scales of typical starbursts. We show also that starbursts seem to obey a limiting IR surface brightness of about 10{sup 11} {ital L}{sub {circle_dot}} kpc{sup 2}, corresponding to a maximum star formation rate of about 20 {ital M}{sub {circle_dot}} yr{sup {minus}1} kpc{sup 2} for a normal initial mass function. We argue that this upper limit suggests that starbursts are self-regulating in some way. We show that most of these galaxies have relatively normal, symmetric rotation curves. This implies that the galactic disk need not suffer severe dynamical damage in order to {open_quotes}fuel{close_quotes} a typical starburst. We show also that the starbursts occur preferentially in the inner region of solid-body rotation. This may reflect both bar-driven inflow of gas to the region between the inner Lindblad resonances and the dominance of gravitational instability over tidal shear in this region. (Abstract Truncated)

• OSTI ID: 501309
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 472; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
COSMIC DUST
DYNAMICS
GALAXIES
INFRARED RADIATION
LUMINOSITY
ROTATION
SPECTROPHOTOMETRY
STAR EVOLUTION