2,552 research outputs found
Local Interstellar Medium Kinematics towards the Southern Coalsack and Chamaeleon-Musca dark clouds
The results of a spectroscopic programme aiming to investigate the kinematics
of the local interstellar medium components towards the Southern Coalsack and
Chamaeleon-Musca dark clouds are presented. The analysis is based upon
high-resolution (R ~ 60,000) spectra of the insterstellar NaI D absorption
lines towards 63 B-type stars (d < 500 pc) selected to cover these clouds and
the connecting area defined by the Galactic coordinates: 308 > l > 294 and -22
< b < 5. The radial velocities, column densities, velocity dispersions, colour
excess and photometric distances to the stars are used to understand the
kinematics and distribution of the interstellar cloud components. The analysis
indicates that the interstellar gas is distributed in two extended sheet-like
structures permeating the whole area, one at d < 60 pc and another around
120-150 pc from the Sun. The dust and gas feature around 120-150 pc seem to be
part of an extended large scale feature of similar kinematic properties,
supposedly identified with the interaction zone of the Local and Loop I
bubbles.Comment: 19 pages, accepted for MNRA
Radiation effects on silicon Final report, Jun. 1, 1964 - May 31, 1965
Radiation effects on silicon - degradation of carrier lifetime in N and P type silicon samples exposed to 30 MeV electron irradiatio
The harmonic power spectrum of the soft X-ray background I. The data analysis
Fluctuations of the soft X-ray background are investigated using harmonic
analysis. A section of the ROSAT All-Sky Survey around the north galactic pole
is used. The flux distribution is expanded into a set of harmonic functions and
the power spectrum is determined. Several subsamples of the RASS have been used
and the spectra for different regions and energies are presented. The effects
of the data binning in pixels are assessed and taken into account. The spectra
of the analyzed samples reflect both small scale effects generated by strong
discrete sources and the large scale gradients of the XRB distribution. Our
results show that the power spectrum technique can be effectively used to
investigate anisotropy of the XRB at various scales. This statistics will
become a useful tool in the investigation of various XRB components.Comment: 12 pages, A&A accepte
Probing the structure of the cold dark matter halo with ancient mica
Mica can store (for >1 Gy) etchable tracks caused by atoms recoiling from
WIMPs. Ancient mica is a directional detector despite the complex motions it
makes with respect to the WIMP "wind". We can exploit the properties of
directionality and long integration time to probe for structure in the dark
matter halo of our galaxy. We compute a sample of possible signals in mica for
a plausible model of halo structure.Comment: 7 pages, 2 figure
Missing baryons and the soft X-ray background
The X-ray background intensity around Lick count galaxies and rich clusters
of galaxies is investigated in three ROSAT energy bands. It is found that the
X-ray enhancements surrounding concentrations of galaxies exhibit significantly
softer spectrum than the standard cluster emission and the average
extragalactic background. The diffuse soft emission accompanying the galaxies
is consistent with the thermal emission of the hot gas postulated first by the
Cen & Ostriker hydrodynamic simulations. Our estimates of the gas temperature -
although subject to large uncertainties - averaged over several Mpc scales are
below 1 keV, which is substantially below the temperature of the intra-cluster
gas, but consistent with temperatures predicted for the local intergalactic
medium. It is pointed out that the planned ROSITA mission would be essential
for our understanding of the diffuse thermal component of the background.Comment: AA accepted, 6 pages, incl. 4 figure
Radiation effects on silicon second quarterly progress report, sep. 1 - nov. 30, 1964
Electron spin resonance measurements on P-doped silicon - vacancy phosphorus defec
The XMM-Newton EPIC Background and the production of Background Blank Sky Event Files
We describe in detail the nature of XMM-Newton EPIC background and its
various complex components, summarising the new findings of the XMM-Newton EPIC
background working group, and provide XMM-Newton background blank sky event
files for use in the data analysis of diffuse and extended sources. Blank sky
event file data sets are produced from the stacking of data, taken from 189
observations resulting from the Second XMM-Newton Serendipitous Source
Catalogue (2XMMp) reprocessing. The data underwent several filtering steps,
using a revised and improved method over previous work, which we describe in
detail. We investigate several properties of the final blank sky data sets. The
user is directed to the location of the final data sets. There is a final data
set for each EPIC instrument-filter-mode combination.Comment: Paper accepted by A&A 22 December 2006. 14 pages, 8 figures. Paper
can also be found at http://www.star.le.ac.uk/~jac48/publications
Radiation effects on silicon third quarterly progress report, dec. 1, 1964 - feb. 28, 1965
Radiation effect on silicon - introduction rates of vacancy-phosphorus defect and divacancy in p-type material for solar cell applicatio
Comments on "Limits on Dark Matter Using Ancient Mica"
To appear in Phys. Rev. Lett. together with the author's Reply.Comment: Compressed PostScript (filename.ps.Z), 3 pages, no figure
OMCat: Catalogue of Serendipitous Sources Detected with the XMM-Newton Optical Monitor
The Optical Monitor Catalogue of serendipitous sources (OMCat) contains
entries for every source detected in the publicly available XMM-Newton Optical
Monitor (OM) images taken in either the imaging or ``fast'' modes. Since the OM
is coaligned and records data simultaneously with the X-ray telescopes on
XMM-Newton, it typically produces images in one or more near-UV/optical bands
for every pointing of the observatory. As of the beginning of 2006, the public
archive had covered roughly 0.5% of the sky in 2950 fields.
The OMCat is not dominated by sources previously undetected at other
wavelengths; the bulk of objects have optical counterparts. However, the OMCat
can be used to extend optical or X-ray spectral energy distributions for known
objects into the ultraviolet, to study at higher angular resolution objects
detected with GALEX, or to find high-Galactic-latitude objects of interest for
UV spectroscopy.Comment: 25 pages, 22 figures, submitted to PAS
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