3,956 research outputs found
Study of ISM tracers in galaxies
We collected data for two samples of normal and interacting galaxies for a
total of 2953 galaxies having fluxes in one or more of the following wavebands:
FIR, 21 cm line, CO(1-0) lines and soft X-ray. The large set of data obtained
allowed us to revisit some of the already known relations between the different
tracers of the interstellar medium (ISM), such as the link between the FIR flux
and the CO line emission, the relation between X-ray emission and the blue or
FIR luminosity. The relation lacking from observations for early-type galaxies
has been discussed and explained in detail in the frame of a suitable
theoretical model, obtained by coupling chemo-dynamical N-body simulations with
a dusty spectrophotometric code of population synthesis.Comment: 2 pages, o appear in the Proceedings of the Conf. "From Stars to
Galaxies: Building the Pieces to Build Up the Universe", Vallenari et al.
eds., ASP Conf. Serie
The WINGS Survey: a progress report
A two-band (B and V) wide-field imaging survey of a complete, all-sky X-ray
selected sample of 78 clusters in the redshift range z=0.04-0.07 is presented.
The aim of this survey is to provide the astronomical community with a complete
set of homogeneous, CCD-based surface photometry and morphological data of
nearby cluster galaxies located within 1.5 Mpc from the cluster center. The
data collection has been completed in seven observing runs at the INT and
ESO-2.2m telescopes. For each cluster, photometric data of about 2500 galaxies
(down to V~23) and detailed morphological information of about 600 galaxies
(down to V~21) are obtained by using specially designed automatic tools.
As a natural follow up of the photometric survey, we also illustrate a long
term spectroscopic program we are carrying out with the WHT-WYFFOS and AAT-2dF
multifiber spectrographs. Star formation rates and histories, as well as
metallicity estimates will be derived for about 350 galaxies per cluster from
the line indices and equivalent widths measurements, allowing us to explore the
link between the spectral properties and the morphological evolution in high-
to low-density environments, and across a wide range in cluster X-ray
luminosities and optical properties.Comment: 12 pages, 10 eps figures, Proceedings of the SAIt Conference 200
On the use of scaling relations for the Tolman test
The use of relations between structural parameters of early type galaxies to
perform the Tolman test is reconsidered. Scaling relations such as the FP or
the Kormendy relation, require the transformation from angular to metric sizes,
to compare the relation at different z values. This transformation depends on
the assumed world model: galaxies of a given angular size, at a given z, are
larger (in kpc) in a non-expanding universe than in an expanding one.
Furthermore, the luminosities of galaxies are expected to evolve with z in an
expanding model. These effects are shown to conspire to reduce the difference
between the predicted SB change with redshift in the expanding and non
expanding cases. We find that the predictions for the visible photometric bands
of the expanding models with passive luminosity evolution are very similar to
those of the static model till z about 1, and therefore, the test cannot
distinguish between the two world models. Recent good quality data are
consistent with the predictions from both models. In the K-band, where the
expected (model) luminosity evolutionary corrections are smaller, the
differences between the xpanding and static models amount to about 0.4 (0.8)
magnitudes at z = 0.4 (1). It is shown that, due to that small difference
between the predictions in the covered z-range, and to the paucity and
uncertainties of the relevant SB photometry, the existing K-band data is not
adequate to distinguish between the different world metrics, and cannot be yet
used to discard the static case. It is pointed out that the scaling relations
could still be used to rule out the non-evolving case if it could be shown that
the coefficients change with the redshift.Comment: Latex, 15 pages with 2 figures. To be published in ApJ Letter
The Orthogonal Gaseous Kinematical Decoupling in the Sa Spiral NGC 2855
We present major and minor-axis kinematics of stars and ionized gas as well
as narrow and broad-band surface photometry of the Sa spiral NGC 2855. In the
nuclear regions of this unbarred and apparently undisturbed spiral galaxy the
gas is rotating perpendicularly to the galaxy disk. We suggest that this
kinematically-decoupled component is the signature of an acquisition process in
the history of this galaxy.Comment: 7 pages, 4 PostScript figures. Accepted for pubblication in A&A.
Figs. 1 and 3 at lower resolution. Data tables will be available at CD
Scaling relations of cluster elliptical galaxies at z~1.3. Distinguishing luminosity and structural evolution
[Abridged] We studied the size-surface brightness and the size-mass relations
of a sample of 16 cluster elliptical galaxies in the mass range
10^{10}-2x10^{11} M_sun which were morphologically selected in the cluster RDCS
J0848+4453 at z=1.27. Our aim is to assess whether they have completed their
mass growth at their redshift or significant mass and/or size growth can or
must take place until z=0 in order to understand whether elliptical galaxies of
clusters follow the observed size evolution of passive galaxies. To compare our
data with the local universe we considered the Kormendy relation derived from
the early-type galaxies of a local Coma Cluster reference sample and the WINGS
survey sample. The comparison with the local Kormendy relation shows that the
luminosity evolution due to the aging of the stellar content already assembled
at z=1.27 brings them on the local relation. Moreover, this stellar content
places them on the size-mass relation of the local cluster ellipticals. These
results imply that for a given mass, the stellar mass at z~1.3 is distributed
within these ellipticals according to the same stellar mass profile of local
ellipticals. We find that a pure size evolution, even mild, is ruled out for
our galaxies since it would lead them away from both the Kormendy and the
size-mass relation. If an evolution of the effective radius takes place, this
must be compensated by an increase in the luminosity, hence of the stellar mass
of the galaxies, to keep them on the local relations. We show that to follow
the Kormendy relation, the stellar mass must increase as the effective radius.
However, this mass growth is not sufficient to keep the galaxies on the
size-mass relation for the same variation in effective radius. Thus, if we want
to preserve the Kormendy relation, we fail to satisfy the size-mass relation
and vice versa.Comment: Accepted for publication in A&A, updated to match final journal
versio
New photometric investigation of the double ringed galaxy ESO474-G26. Unveiling the formation scenario
We present a detailed photometric study of the peculiar double ringed galaxy
ESO474-G26. Near-Infrared (NIR) and optical data have been used, with the main
goal to constrain the formation history of ESO474-G26. NIR photometry is
fundamental in this kind of study, because gives better constraints on the
Spectral Energy Distribution (SED) and well traces the older stellar population
of the galaxy. This galaxy presents a very complex structure, with two almost
orthogonal rings, one in the equatorial and another in the polar plane, around
an elliptical-like object. Due to the peculiar morphology of ESO474-G26, we
used both NIR images (J and K bands) to derive accurate analysis of the stellar
light distribution, and optical images (in the B, V and R bands) to derive
color profiles and color maps to study the structure of the rings. The
observational characteristic of ESO474-G26 are typical of galaxies which have
experienced some kind of interactions during their evolution. We investigated
two alternatives: a merging process and an accretion event.Comment: 19 pages, 20 figures. Accepted for publication in Monthly Notices of
the Royal Astronomical Society (MNRAS
Chromatic confocal setup for displacement measurement using a supercontinuum light source
Chromatic confocal microscopy is a technique to measure distances by analyzing the spectrum of the light reflected by a sample. The key element of the confocal setup is a dispersive lens, which focuses
different wavelengths at different distances from the lens. In this paper,a novel setup realized with a
supercontinuum light source and a spatial filter composed by reflective elements is described.The supercontinuum source is implemented by injecting high power pulses from a microchip laser into a
Ge-doped microstructured optical fiber. The usage of metallic parabolic mirrors, for the focusing and
collimation required in the spatial filter, lets the dispersive lens be the only dispersive element of the
confocal setup and improves the efficiency of the spatial filter itself. A silicon-based spectrometer is
used for the acquisition of the spectra, which are normalized and Gaussian-fitted before extracting the
displacement information. A complete calibration is performed, and the set of wavelengths from
500 nm to 900 nm can be mapped into a280 um measuring range. The obtained relativ eaccuracy of
0.36% shows an enhancement of almost one order of magnitude when compared to other supercontinuum-based confocal systems
Discovery of a Boxy Peanut Shaped Bulge in the Near Infrared
We report on the discovery of a boxy/peanut shaped bulge in the highly
inclined barred Seyfert 2 galaxy NGC~7582. The peanut shape is clearly evident
in near infrared images but obscured by extinction from dust in visible
images. This suggests that near infrared imaging surveys will discover a
larger number of boxy/peanut morphologies than visible surveys, particularly in
galaxies with heavy extinction such as NGC~7582. The bulge in NGC~7582 exhibits
strong boxiness compared to other boxy/peanut shaped bulges. If the starburst
was mediated by the bar, then it is likely that the bar formed in less than a
few bar rotation periods or a few years ago. If the bar also
caused the peanut, then the peanut would have formed quickly; on a timescale of
a few bar rotation periods.Comment: AAS Latex and Postcript Figures, accepted for publication in Ap
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