2,147 research outputs found
Chain Galaxies are Edge-On Low Surface Brightness Galaxies
Deep HST WFPC2 images have revealed a population of very narrow blue galaxies
which Cowie et al. (1996) have interpreted as being a new morphological class
of intrinsically linear star forming galaxies at . We show that the
same population exists in large numbers at low redshifts (z=0.03) and are
actually the edge-on manifestation of low surface brightness disk galaxies.Comment: 18 pages + 3 pages of figures. Uuencoded, gzipped, tar file of 1
latex file, 5 figures, and 2 latex style files. To appear in the
Astrophysical Journal Letter
On the investigations of galaxy redshift periodicity
In this article we present a historical review of study of the redshift
periodicity of galaxies, starting from the first works performed in the
seventies of the twentieth century until the present day. We discuss the
observational data and methods used, showing in which cases the discretization
of redshifts was observed. We conclude that galaxy redshift periodisation is an
effect which can really exist. We also discussed the redshift discretization in
two different structures: the Local Group of galaxies and the Hercules
Supercluster. Contrary to the previous studies we consider all galaxies which
can be regarded as a structure member disregarding the accuracy of velocity
measurements. We applied the power spectrum analysis using the Hann function
for weighting, together with the jackknife error estimator. In both the
structures we found weak effects of redshift periodisation.Comment: 10 pages, 4 figures, to be published in Part. and Nucl. Lett. 200
A warped disk model for M33 and the 21-cm line width in spiral galaxies
To determine the actual HI distribution and the velocity field in the
outermost disk of the spiral galaxy M33, a tilted-ring model is fitted to 21-cm
line data taken with the Arecibo Telescope. Since M33 is one of the main
calibrators for the extragalactic distance scale derived through the
Tully-Fisher relation, the outer disk warping is of interest for a correct
determination and deprojection of the galaxy's line width. Even though our best
model predicts small effects on the observed line width of M33, we show that
similar outer disk warping in galaxies oriented differently along our line of
sight could affect the widths considerably. Therefore there may be systematic
effects in the determination of the rotation velocities and dynamic masses of
spiral galaxies, whose exact value depends also on which method is used for
measuring the galaxy's total line width.Comment: 27 pages, ps files only, ApJ in pres
Effective Feedback to Improve Primary Care Prescribing Safety (EFIPPS) a pragmatic three-arm cluster randomised trial:designing the intervention (ClinicalTrials.gov registration NCT01602705)
Peer reviewedPublisher PD
[Editorial] Accounting scholarship and management by numbers
There is a plethora of indices ranking universities, departments, and individual researchers based on a variety of indices. These invariably include a measurement of research, usually based on a combination of quantity and quality of journal publications. Informal discussions with accounting researchers invariably turns to the question of journal rankings and performance management indicators. Why is this so
On the relation between circular velocity and central velocity dispersion in high and low surface brightness galaxies
In order to investigate the correlation between the circular velocity Vc and
the central velocity dispersion of the spheroidal component sigma_c, we
analyzed these quantities for a sample of 40 high surface brightness disc
galaxies (hereafter HSB), 8 giant low surface brightness spiral galaxies
(hereafter LSB), and 24 elliptical galaxies characterized by flat rotation
curves. We find that the Vc-sigma_c relation is descri ed by a linear law out
to velocity dispersions as low as sigma_c~50km/s, while in previous works a
power law was adopted for galaxies with sigma_c>80k/ms.
Elliptical galaxies with Vc based on dynamical models or directly derived
from the HI rotation curves follow the same relation as the HSB galaxies in the
Vc-sigma_c plane. On the contrary, the LSB galaxies follow a different
relation, since most of them show either higher Vc (or lower sigma_c) with
respect to the HSB galaxies. This argues against the relevance of baryon
collapse in the radial density profile of the dark matter haloes of LSB
galaxies. (abridged)Comment: 18 pages, 4 figures, ApJ in pres
Corporate Social Responsibility and Islamic Financial Institutions (IFIs): Management Perceptions from IFIs in Bahrain
Islamic finance is gaining greater attention in the finance industry, and this paper analyses how Islamic financial institutions (IFIs) are responding to the welfare needs of society. Using interview data with managers and content analysis of the disclosures, this study attempts to understand management perceptions of corporate social
responsibility (CSR) in IFIs. A thorough understanding of CSR by managers, as evident in the interviews, has not been translated fully into practice. The partial use of IFIs’ potential role in social welfare would add further challenges in the era of financialisation
Extraplanar Emission-Line Gas in Edge-On Spiral Galaxies. II. Optical Spectroscopy
The results from deep long-slit spectroscopy of nine edge-on spiral galaxies
with known extraplanar line emission are reported. Emission from Halpha, [N II]
lambda 6548, 6583, and [S II] lambda 6716, 6731 is detected out to heights of a
few kpc in all of these galaxies. Several other fainter diagnostic lines such
as [O I] lambda 6300, [O III] lambda 4959, 5007, and He I lambda 5876 are also
detected over a smaller scale. The relative strengths, centroids and widths of
the various emission lines provide constraints on the electron density,
temperature, reddening, source(s) of ionization, and kinematics of the
extraplanar gas. In all but one galaxy, photoionization by massive OB stars
alone has difficulties explaining all of the line ratios in the extraplanar
gas. Hybrid models that combine photoionization by OB stars and another source
of ionization such as photoionization by turbulent mixing layers or shocks
provide a better fit to the data. The (upper limits on the) velocity gradients
measured in these galaxies are consistent with the predictions of the galactic
fountain model to within the accuracy of the measurements.Comment: 25 pages + several jpg figures. Accepted for publication in the
Astrophysical Journal, Vol. 592, July 20 200
Twenty Years of Galactic Observations in Searching for Bursts of Collapse Neutrinos with the Baksan Underground Scintillation Telescope
The results of twenty-year-long Galactic observations in neutrino radiation
are summarized. Except for the recording of a neutrino signal from the
supernova SN 1987A, no Galactic bursts of collapse neutrinos have been
detected. An upper bound on the mean frequency of gravitational collapses in
our Galaxy was obtained, .Comment: latex, 7 pages, 2 eps figure
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