570 research outputs found
2335 Evaluation of anterior chamber angle: Gonioscopy, ultrasound biomicroscopy and scheimpflug photography
Aprovat per la Comissió de Govern de 10-09-2014El termini de la suspensió serà, com a màxim, d'un any, a comptar des de l'endemà de la publicació al BO
Servicio de distribución electrónica de sumarios
Sección: NoticiasA partir del mes de febrero, la biblioteca del Instituto de Microelectrónica de Barcelona (IMB-CNM) pone en marcha el Servicio de distribución electrónica de sumarios a través de la base de datos SwetsNet.N
Nuclear Star Clusters across the Hubble Sequence
Over the last decade, HST imaging studies have revealed that the centers of
most galaxies are occupied by compact, barely resolved sources. Based on their
structural properties, position in the fundamental plane, and spectra, these
sources clearly have a stellar origin. They are therefore called ``nuclear star
clusters'' (NCs) or ``stellar nuclei''. NCs are found in galaxies of all Hubble
types, suggesting that their formation is intricately linked to galaxy
evolution. In this contribution, I briefly review the results from recent
studies of NCs, touch on some ideas for their formation, and mention some open
issues related to the possible connection between NCs and supermassive black
holes.Comment: 6 page conference proceedings, to appear in "The impact of HST on
European Astronomy" (41st ESLAB Symposium), pdflatex file, uses svmult.cls
(included
Evolution in the Dust Lane Fraction of Edge-on L* Spiral Galaxies since z=0.8
The presence of a well-defined and narrow dust lane in an edge-on spiral
galaxy is the observational signature of a thin and dense molecular disk, in
which gravitational collapse has overcome turbulence. Using a sample of
galaxies out to z~1 extracted from the COSMOS survey, we identify the fraction
of massive disks that display a dust lane. Our goal is to explore the evolution
in the stability of the molecular ISM disks in spiral galaxies over a cosmic
timescale. We check the reliability of our morphological classifications
against changes in restframe wavelength, resolution, and cosmic dimming with
(artificially redshifted) images of local galaxies from SDSS. We find that the
fraction of L* disks with dust lanes in COSMOS is consistent with the local
fraction (~80%) out to z~0.7. At z=0.8, the dust lane fraction is only slightly
lower. A somewhat lower dust lane fraction in starbursting galaxies tentatively
supports the notion that a high specific star formation rate can efficiently
destroy or inhibit a dense molecular disk. A small subsample of higher redshift
COSMOS galaxies display low internal reddening (E[B-V]), as well as a low
incidence of dust lanes. These may be disks in which the growth of the dusty
ISM disk lags behind that of the stellar disk. We note that at z=0.8, the most
massive galaxies display a lower dust lane fraction than lower mass galaxies. A
small contribution of recent mergers or starbursts to this most massive
population may be responsible. The fact that the fraction of galaxies with dust
lanes in COSMOS is consistent with little or no evolution implies that models
to explain the Spectral Energy Distribution or the host galaxy dust extinction
of supernovae based on local galaxies are still applicable to higher redshift
spirals. It also suggests that dust lanes are long lived phenomena or can be
reformed over very short time-scales.Comment: 14 pages, 9 figures, 2 tables, accepted for publication by Ap
Polarized Proton Beams from Laser-induced Plasmas
We report on the concept of an innovative source to produce polarized
proton/deuteron beams of a kinetic energy up to several GeV from a laser-driven
plasma accelerator. Spin effects have been implemented into the PIC simulation
code VLPL to make theoretical predictions about the behavior of proton spins in
laser-induced plasmas. Simulations of spin-polarized targets show that the
polarization is conserved during the acceleration process. For the experimental
realization, a polarized HCl gas-jet target is under construction using the
fundamental wavelength of a Nd:YAG laser system to align the HCl bonds and
simultaneously circular polarized light of the fifth harmonic to
photo-dissociate, yielding nuclear polarized H atoms. Subsequently, their
degree of polarization is measured with a Lamb-shift polarimeter. The final
experiments, aiming at the first observation of a polarized particle beam from
laser-generated plasmas, will be carried out at the 10 PW laser system SULF at
SIOM/Shanghai.Comment: 7 pages, 7 figure
UBVI Surface Photometry of the Spiral Galaxy NGC 300 in the Sculptor Group
We present UBVI surface photometry for 20.'5 X 20.'5 area of a late-type
spiral galaxy NGC 300. In order to understand the morphological properties and
luminosity distribution characteristics of NGC 300, we have derived isophotal
maps, surface brightness profiles, ellipticity profiles, position angle
profiles, and color profiles. By merging the I-band data of our surface
brightness measurements with those of Boeker et al. (2002) based on Hubble
Space Telescope observations, we have made combined I-band surface brightness
profiles for the region of 0."02 < r < 500" and decomposed the profiles into
three components: a nucleus, a bulge, and an exponential disk.Comment: 16 pages(cjaa209.sty), Accepted by the Chinese J. Astron. Astrophys.,
Fig 2 and 8 are degraded to reduce spac
Supermassive black holes do not correlate with dark matter halos of galaxies
Supermassive black holes have been detected in all galaxies that contain
bulge components when the galaxies observed were close enough so that the
searches were feasible. Together with the observation that bigger black holes
live in bigger bulges, this has led to the belief that black hole growth and
bulge formation regulate each other. That is, black holes and bulges
"coevolve". Therefore, reports of a similar correlation between black holes and
the dark matter halos in which visible galaxies are embedded have profound
implications. Dark matter is likely to be nonbaryonic, so these reports suggest
that unknown, exotic physics controls black hole growth. Here we show - based
in part on recent measurements of bulgeless galaxies - that there is almost no
correlation between dark matter and parameters that measure black holes unless
the galaxy also contains a bulge. We conclude that black holes do not correlate
directly with dark matter. They do not correlate with galaxy disks, either.
Therefore black holes coevolve only with bulges. This simplifies the puzzle of
their coevolution by focusing attention on purely baryonic processes in the
galaxy mergers that make bulges.Comment: 12 pages, 9 Postscript figures, 1 table; published in Nature (20
January 2011
- …