552 research outputs found
Asymmetrical structure of ionization and kinematics in the Seyfert galaxy NGC 5033
We present integral field spectroscopy of NGC 5033, a low luminosity Seyfert
galaxy. The observations were made with INTEGRAL, a fiber based system
operating at the WHT. The intensity map of the H emission line
represents a spiral or ring-like pattern of HII regions. On the contrary, the
[OIII] intensity map morphology is markedly anisotropic. The strong
morphological differences imply that the [OIII] emitters represent highly
ionized gas illuminated by the central source. The [OIII] map morphology is
compatible with a biconical structure of ionization induced by strong
extinction in the galaxy disc that also obscures half of the spheroidal stellar
bulge. We identify the spectrum corresponding to the Seyfert 1 nucleus from the
presence of H broad emission lines. This spectrum is located in a region
where strong extinction is expected but exhibits the bluest spectral energy
distribution. The Seyfert 1 nucleus seems to be offcenter with respect to the
stellar rotation center. This result has been also found in other Seyfert
galaxies and interpreted in terms of a past merger. The offcentering could
indicate the presence of nonsymmetric departures in the gravitational potential
which could be fueling the active nucleus. The kinematics of the [OIII]
emitters show important deviations at a kpc scale with respect to the stellar
velocity field and show features related to the asymmetrical morphology of the
high ionization region.Comment: 9 pages, accepted for publication in Astronomy and Astrophysics.
Figures 1 and 7 are attached as .gif file
Integral Field Spectroscopy based H\alpha\ sizes of local Luminous and Ultraluminous Infrared Galaxies. A Direct Comparison with high-z Massive Star Forming Galaxies
Aims. We study the analogy between local U/LIRGs and high-z massive SFGs by
comparing basic H{\alpha} structural characteristics, such as size, and
luminosity (and SFR) surface density, in an homogeneous way (i.e. same tracer
and size definition, similar physical scales). Methods. We use Integral Field
Spectroscopy based H{\alpha} emission maps for a representative sample of 54
local U/LIRGs (66 galaxies). From this initial sample we select 26 objects with
H{\alpha} luminosities (L(H{\alpha})) similar to those of massive (i.e. M\ast
\sim 10^10 M\odot or larger) SFGs at z \sim 2, and observed on similar physical
scales. Results. The sizes of the H{\alpha} emitting region in the sample of
local U/LIRGs span a large range, with r1/2(H{\alpha}) from 0.2 to 7 kpc.
However, about 2/3 of local U/LIRGs with Lir > 10^11.4 L\odot have compact
H{\alpha} emission (i.e. r1/2 < 2 kpc). The comparison sample of local U/LIRGs
also shows a higher fraction (59%) of objects with compact H{\alpha} emission
than the high-z sample (25%). This gives further support to the idea that for
this luminosity range the size of the star forming region is a distinctive
factor between local and distant galaxies of similar SF rates. However, when
using H{\alpha} as a tracer for both local and high-z samples, the differences
are smaller than the ones recently reported using a variety of other tracers.
Despite of the higher fraction of galaxies with compact H{\alpha} emission, a
sizable group (\sim 1/3) of local U/LIRGs are large (i.e. r1/2 > 2 kpc). These
are systems showing pre-coalescence merger activity and they are
indistinguishable from the massive high-z SFGs galaxies in terms of their
H{\alpha} sizes, and luminosity and SFR surface densities.Comment: Accepted for publication in A&A. (!5 pages, 7 figures, 2 tables
Geoquímica del W en el área circundante al yacimiento de cheelita de Barruecopardo (Salamanca)
La microclinización, proceso ácido débil, implica una corrosión de plagioclasas y una transformación biotita-clorita, con paso del W de dicha biotita a la fase volátil, bajo forma compleja. El descenso de presión en las fisuras (filones) hace precipitar a los wolframatos. Este mecanismo explica el empobrecimiento en W en las inmediaciones del yacimiento, y justifica una explicación geoquímica y mineralógica expuesta precedentemente
Integral field optical spectroscopy of a representative sample of ULIRGs: I. The Data
We present a project aimed at studying the structure, dust distribution,
ionization state, and kinematics of a representative sample of 22 ULIRGs. The
galaxies in the sample undergo different merger phases (they are evenly divided
between pre- and post-coalescence systems) and ionization stages (27% HII, 32%
LINER, 18% Seyfert, and 23% mixed classifications) over a wide infrared
luminosity range (11.8<Lir/Lsun<12.6), which also includes some galaxies of low
luminosity. The main aims of this paper are to present the sample and discuss
the structure of the stellar and ionized gas components. Our results imply that
evolution caused by a merger is occurring in the ionized gas structure of
ULIRGs. The present study relies on the use of integral field optical
spectroscopy data obtained with the INTEGRAL instrument at the 4.2 m William
Herschel Telescope.Comment: To appear in A&A. Paper with higher quality images can be found at
http://hera.ph1.uni-koeln.de/ftpspace/maca/Catalog
Non-circular motion evidences in the circumnuclear region of M100 (NGC 4321)
We analyse new integral field spectroscopy of the inner region (central 2.5
kpc) of the spiral galaxy NGC 4321 to study the peculiar kinematics of this
region. Fourier analysis of the velocity residuals obtained by subtracting an
axisymmetric rotation model from the velocity field, indicates
that the distortions are {\em global} features generated by an
perturbation of the gravitational potential which can be explained by the
nuclear bar. This bar has been previously observed in the near-infrared but not
in the optical continuum dominated by star formation. We detect the optical
counterpart of this bar in the 2D distribution of the old stellar population
(inferred from the equivalent width map of the stellar absorption lines). We
apply the Tremaine--Weinberg method to the stellar velocity field to calculate
the pattern speed of the inner bar, obtaining a value of
=160. This value is considerably la
rger than the one obtained when a simple bar model is considered. However the
uncertainties in the pattern speed determination prevent us to give support to
alternative scenarios.Comment: 11 pages, 11 figures, accepted for publication in MNRA
Axisymmetrical Gas Inflow in the Central Region of NGC 7331
New Integral Field Spectroscopy of the central region of NGC 7331 reveals
strong H emission in the well-known CO and HI ring of NGC 7331. The
[NII]/H ratio indicates that a large scale stellar formation process is
taken place at the ring in agreement with previous hypothesis about the
exhaustion of gas in the inner to the ring region. The dynamics of stars and
gas are not coupled. There is a ring of peculiar velocities in the ionized gas
velocity map. These peculiar velocities can be well interpreted by the presence
of an axisymmetric inflow of 40 km/s at the inner boundary of the large-scale
gaseous ring. We infer an inwards total flux of 1.6 Myr. This
value is typical of the accretion rates in hypothetical {\bf large} nuclear
black holes. Despite the large differences in the scales of the nucleus and the
gas ring of NGC 7331, we suggest that this inwards flux is feeding the nucleus.Comment: 5 pages, 3 figures, to be published in Astronomy and Astrophysic
Influence of the epoxy/amine stoichiometry on the thermomechanical properties of nanocomposites based on high Tg epoxy and organophilic clays.
In layered silicate-epoxy nanocomposites organic modification of the silicates makes them compatible with the epoxy which intercalates into the clay galleries. The effect of clay dispersion on epoxies of high Tg is not clear. Decreases of the epoxy Tg have been frequently reported. The presence of clay may cause stoichiometry imbalances that conduces to the formation of imperfect network
Propiedades de nanocompuestos de matriz termoestable con nuevos organosilicatos laminares
En este trabajo se han preparado nanocompuestos de matriz polímero termoestable del tipo poliéster insaturado y epoxídica utilizando como refuerzo nanosilicatos laminares que se han modificado específicamente para mejorar la interacción con la matriz. En concreto se han modificado montmorillonitas con cationes orgánicos reactivos con la matriz de poliéster insaturado. Asimismo se han silanizado montmorillonitas comerciales orgánicamente modificadas con el objetivo de formar enlaces químicos con la matriz epoxídica. En ambos nanocompuestos se han estudiado las propiedades termo- mecánicas pudiendo comprobar la efectividad de los nuevos organosilicatos
VLT-VIMOS integral field spectroscopy of luminous and ultraluminous infrared galaxies II. Evidence for shock ionization caused by tidal forces in the extra-nuclear regions of interacting and merging LIRGs
LIRGs are an important class of objects in the low-z universe bridging the
gap between normal spirals and the strongly interacting and starbursting
ULIRGs. Studies of their 2D physical properties are still lacking. We aim to
understand the nature and origin of the ionization mechanisms operating in the
extranuclear regions of LIRGs as a function of the interaction phase and L_IR
by using IFS data obtained with VIMOS. Our analysis is based on over 25300
spectra of 32 LIRGs covering all types of morphologies and the entire
10^11-10^12 L_sun range. We found strong evidence for shock ionization, with a
clear trend with the dynamical status of the system. Specifically, we
quantified the variation with interaction phase of several line ratios
indicative of the excitation degree. While the [NII]/Ha ratio does not show any
significant change, the [SII]/Ha and [OI]/Ha ratios are higher for more
advanced interaction stages. We constrained the main mechanisms causing the
ionization in the extra-nuclear regions using diagnostic diagrams. Isolated
systems are mainly consistent with ionization caused by young stars. Large
fractions of the extra-nuclear regions in interacting pairs and more advanced
mergers are consistent with ionization caused by shocks. This is supported by
the relation between the excitation degree and the velocity dispersion of the
ionized gas, which we interpret as evidence for shock ionization in interacting
galaxies and advanced mergers but not in isolated galaxies. This relation does
not show any dependence with L_IR. All this indicates that tidal forces play a
key role in the origin of the ionizing shocks in the extra-nuclear regions. We
also showed what appears to be a common [OI]/Ha-sigma relation for the
extranuclear ionized gas in interacting (U)LIRGs. This needs to be investigated
further with a larger sample of ULIRGs.Comment: Accepted for publication in Astronomy and Astrophysics. Some figures
were removed due to space limitations. A version with the whole set of
figures can be seen at
http://www.damir.iem.csic.es/extragalactic/publications/publications.htm
PMAS integral field spectroscopy of luminous infrared galaxies. I.- The atlas
In this paper we present PMAS optical (3800-7200A) IFS of the northern
hemisphere portion of a volume-limited sample of 11 LIRGs. The PMAS
observations typically cover the central ~5kpc and are complemented with
HST/NICMOS images. For most LIRGs in our sample, the peaks of the continuum and
gas (e.g., Halpha, [NII]) emissions coincide, unlike what is observed in local,
strongly interacting ULIRGs. The only exceptions are galaxies with
circumnuclear rings of star formation where the most luminous Halpha emitting
regions are found in the rings rather than in the nuclei, and the displacements
are well understood in terms of differences in the stellar populations. A large
fraction of the nuclei of these LIRGs are classified as LINER and intermediate
LINER/HII, or composite objects. The excitation conditions of the integrated
emission depend on the relative contributions of HII regions and the diffuse
emission to the line emission over the PMAS FoV. Galaxies dominated by high
surface-brightness HII regions show integrated HII-like excitation. A few
galaxies show slightly larger integrated [NII]/Halpha and [SII]/Halpha line
ratios than the nuclear ones, probably because of more contribution from the
diffuse emission. The Halpha velocity fields over the central few kpc are
generally consistent, at least to first order, with rotational motions. The
velocity fields of most LIRGs are similar to those of disk galaxies, in
contrast to the highly perturbed fields of most local, strongly interacting
ULIRGs. The peak of the Halpha velocity dispersion coincides with the position
of the nucleus and is likely to be tracing mass. All these results are similar
to the properties of z~1 LIRGs, and they highlight the importance of detailed
studies of flux-limited samples of local LIRGs. (Abridged)Comment: Accepted for publication in Astronomy and Astrophysic
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