36 research outputs found
The Asymmetric Wind in M82
We have obtained detailed imaging Fabry-Perot observations of the nearby
galaxy M82, in order to understand the physical association between the
high-velocity outflow and the starburst nucleus. The observed velocities of the
emitting gas in M82 reveal a bipolar outflow of material, originating from the
bright starburst regions in the galaxy's inner disk, but misaligned with
respect to the galaxy spin axis. The deprojected outflow velocity increases
with radius from 525 to 655 km/s. Spectral lines show double components in the
centers of the outflowing lobes, with the H-alpha line split by ~300 km/s over
a region almost a kiloparsec in size. The filaments are not simple surfaces of
revolution, nor is the emission distributed evenly over the surfaces. We model
these lobes as a composite of cylindrical and conical structures, collimated in
the inner ~500 pc but expanding at a larger opening angle of ~25 degrees beyond
that radius. We compare our kinematic model with simulations of
starburst-driven winds in which disk material surrounding the source is
entrained by the wind. The data also reveal a remarkably low [NII]/H-alpha
ratio in the region of the outflow, indicating that photoionization by the
nuclear starburst may play a significant role in the excitation of the optical
filament gas, particularly near the nucleus.Comment: 42 pages AASTeX with 16 figures; accepted for publication in ApJ;
figures reformatted for better printin
Milestones in the Observations of Cosmic Magnetic Fields
Magnetic fields are observed everywhere in the universe. In this review, we
concentrate on the observational aspects of the magnetic fields of Galactic and
extragalactic objects. Readers can follow the milestones in the observations of
cosmic magnetic fields obtained from the most important tracers of magnetic
fields, namely, the star-light polarization, the Zeeman effect, the rotation
measures (RMs, hereafter) of extragalactic radio sources, the pulsar RMs, radio
polarization observations, as well as the newly implemented sub-mm and mm
polarization capabilities.
(Another long paragraph is omitted due to the limited space here)Comment: Invited Review (ChJA&A); 32 pages. Sorry if your significant
contributions in this area were not mentioned. Published pdf & ps files (with
high quality figures) now availble at http://www.chjaa.org/2002_2_4.ht