NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-26 T21:13:36 PDT
Help | Comment | NED Home

For refcode 2000ApJS..129..493H:
Retrieve 32 NED objects in this reference.
Please click here for ADS abstract

NED Abstract

Copyright by American Astronomical Society. Reproduced by permission
2000ApJS..129..493H Absorption-Line Probes of Gas and Dust in Galactic Superwinds Timothy M. Heckman, Matthew D. Lehnert, David K. Strickland, and Lee Armus Received 1999 October 7; accepted 2000 February 29 ABSTRACT We have obtained moderate resolution (R = few thousand) spectra of the Na I {lambda}{lambda}5890, 5896 (Na D) absorption line in a sample of 32 far-IR-bright starburst galaxies. In 18 cases, the Na D line in the nucleus is produced primarily by interstellar gas, while cool stars contribute significantly in the others. In 12 of the 18 "interstellar-dominated" cases the Na D line is blueshifted by over 100 km s^-1^ relative to the galaxy systemic velocity (the "outflow sources"), while no case shows a net redshift of more than 100 km s^-1^. The absorption-line profiles in these outflow sources span the range from near the galaxy systemic velocity to a maximum blueshift of ~400-600 km s^-1^. The outflow sources are galaxies systematically viewed more nearly face-on than the others. We therefore argue that the absorbing material consists of ambient interstellar material that has been entrained and accelerated along the minor axis of the galaxy by a hot starburst-driven superwind. The Na D lines are optically thick, but indirect arguments imply total hydrogen column densities of N_H_~few x 10^21^cm^-2^. This implies that the superwind is expelling matter at a rate comparable to the star formation rate. This outflowing material is evidently very dusty: we find a strong correlation between the depth of the Na D profile and the line-of-sight reddening. Typical implied values are E(B-V) = 0.3-1 over regions several-to-10 kpc in size. We briefly consider some of the potential implications of these observations. The estimated terminal velocities of superwinds inferred from the present data and extant X-ray data are typically 400-800 km s^-1^, are independent of the galaxy rotation speed, and are comparable to (substantially exceed) the escape velocities for L_*_ (dwarf) galaxies. The resulting selective loss of metals from shallower potential wells can establish the mass-metallicity relation in spheroids, produce the observed metallicity in the intracluster medium, and enrich a general IGM to of order 10-1 solar metallicity. If the outflowing dust grains can survive their journey into the IGM, their effect on observations of cosmologically distant objects would be significant. Subject headings: galaxies: active-galaxies: halos-galaxies: ISM-galaxies: kinematics and dynamics -galaxies: nuclei-galaxies: starburst-intergalactic medium
Retrieve 32 NED objects in this reference.
Please click here for ADS abstract

Back to NED Home