346 research outputs found
Optically Selected Compact Stellar Regions and Tidal Dwarf Galaxies in (Ultra)-Luminous Infrared Galaxies
This thesis work is devoted to the analysis of compact star forming regions
(knots) in a representative sample of 32 (U)LIRGs. The project is based mainly
on optical high angular resolution images taken with the ACS and WFPC2 cameras
on board the HST telescope, data from a high spatial resolution simulation of a
major galaxy encounter, and with the combination of optical integral field
spectroscopy (IFS) taken with the INTEGRAL (WHT) and VIMOS (VLT) instruments. A
few thousand knots -a factor of more than one order of magnitude higher than in
previous studies- are identified and their photometric properties are
characterized as a function of the infrared luminosity of the system and of the
interaction phase. These properties are compared with those of compact objects
identified in simulations of galaxy encounters. Finally, and with the
additional use of IFS data, we search for suitable candidates to tidal dwarf
galaxies, setting up constraints on the formation of these objects for the
(U)LIRG class. Knots in (U)LIRGs are likely to contain sub-strucutre. Evidence
is found that in ULIRGs they are intrinsically more luminous than in less
luminous interacting systems due to size-of-sample effects. Furthermore, their
sizes and masses are similar to stellar complexes or clumps detected in
galaxies at z > 1, unlike local stellar complexes. The star formation in
(U)LIRGs is charaterized by a luminosity function with a slope consistent with
\alpha = 2, independent of the luminosity of the system. However, it may
flatten slightly due to, as simulations suggest, higher knot formation rates at
early phases of the interaction. Candidates to tidal dwarf galaxies are
identified in the sample. With a production rate of 0.1 candidates per (U)LIRG
system, only a few fraction (< 10%) of the general dwarf satellite population
could be of tidal origin
VLT/VIMOS integral field spectroscopy of luminous and ultraluminous infrared galaxies: 2D kinematic properties
We present and discuss the 2D kinematic properties of the ionized gas
(Halpha) in a sample of 38 local (ultra) luminous infrared galaxies [(U)LIRGs]
(31 LIRGs and 7 ULIRGs) observed with VIMOS at the VLT using integral field
spectroscopy. This sample covers well the less studied LIRG luminosity range
and includes isolated disks, interacting systems, and mergers. The majority of
the galaxies have two main kinematically distinct components. One component
(i.e., narrow or systemic) extends over the whole line-emitting region and is
characterized by small to intermediate velocity dispersions (i.e., sigma from
30 to 160 km s^-1). It traces the overall velocity field. The second component
(broad) has in general a larger velocity dispersion (up to 320 km s^-1), mainly
found in the inner regions and generally blueshifted with respect to the
systemic component. Most of the objects (76%) are dominated by rotation, more
relevant in LIRGs than in ULIRGs. Isolated disks, interacting galaxies, and
merging systems define a sequence of increasing mean velocity dispersion, and
decreasing velocity field amplitude.The LIRGs classified as isolated disks have
similar velocity amplitudes but larger mean velocity dispersions (44 vs. 24 km
s^-1) than local spirals, implying a larger turbulence and thicker disks.
Interacting systems and mergers have values closer to those of low velocity
dispersion ellipticals/lenticular galaxies (E/SOs). The (U)LIRGs classified as
mergers have kinematic properties similar to those shown by the Lyman break
analogs (LBAs). The dynamical masses range from \sim 0.04 m* to 1.4 m* (i.e.,
m* = 1.4x10^{11} Msun), with ULIRGs (M{dyn} sim 0.5 +/- 0.2 m*) being more
massive than LIRGs by, on average, a factor of about 2. The mass ratio of
individual pre-coalescence galaxies is <2.5 for most of the systems, confirming
that most (U)LIRG mergers involve sub-m* galaxies of similar mass.Comment: 66 pages, 5 figures plus 45 figures in App. A; accepted for
publication in A&
La irrupción de la economía colaborativa en el sector turístico: análisis del conflicto en el sector del alojamiento.
En los últimos años se viene presenciando un continuo descontento de los agentes
turísticos ante la aparición y falta de regulación de empresas de economía colaborativa en
el sector. Este trabajo tiene como objetivo investigar de manera cualitativa el conflicto
existente entre las plataformas Peer to Peer (P2P) y la oferta reglada en el ámbito del
alojamiento en España. Para alcanzar dicho objetivo se ha analizado la normativa
internacional y se ha implementado una metodología de análisis del discurso mediante un
software específico (Atlas.ti). Se concluye que el sector hotelero busca el descenso de la
actividad de las empresas de economía colaborativa al exigir su regulación, y que los
usuarios P2P seguirán alojándose en estas viviendas mientras crean que aportan un
beneficio económico y/o social en el destino. Asimismo, existen discrepancias sobre cual
es el perfil del cliente de esta tipología de alojamiento.In recent years, a constant dissatisfaction of tourism agents has been latent due to the
appearance and lack of regulation of collaborative economy companies in this sector. This
project aims to explore qualitatively the existing conflict between the Peer to Peer (P2P)
platforms and the regulated offer in the accommodation area. To achieve such purpose,
international regulation has been analyzed and a methodology of discourse analysis has
been implemented using specific software (Atlas.Ti). It is concluded that the hotel
industry seeks the decrease of the collaborative economy activity by requiring its
regulation and also, that the P2P users will continue accommodating in these dwellings
as long as they think that they provide an economic and/or social benefit in the
destination. Additionally, it also exist disagreements about the customer ́s profile of this
type of accommodation
Tratamiento quirúrgico de la incontinencia urinaria de esfuerzo femenina con cabestrillo suburetral sin tensión
Exercise increases the dynamics of diurnal cortisol secretion and executive functionin people wiht MCI
Summary:
Regular physical activity is protective against and beneficial for Mild Cognitive Impairment (MCI), dementia, and Alzheimer´s disease. The mechanisms underlying these benefits remain unknown although it has been suggested that exercise-induced changes in the circadian pattern of cortisol secretion may be implicated. Fitness, salivary cortisol levels (0 and 30 mins post awakening, midday, 5pm and 9pm) and cognitive function were determined in a group of amnestic MCI patients (n=39) before and after a three-month exercise program (n=19) or usual care (n=20). At base fitness measures were positively correlated with peak levels of cortisol and a greater fall in cortisol concentration from peak levels to midday. The exercise intervention successfully increased fitness and resulted in a greater fall in cortisol concentration from peak to midday, compared to the control group. The exercise intervention enhanced indices of executive function, although memory, mood, and functionality were not affected
Star-formation histories of local luminous infrared galaxies
We present the analysis of the integrated spectral energy distribution (SED)
from the ultraviolet (UV) to the far-infrared and H of a sample of 29
local systems and individual galaxies with infrared (IR) luminosities between
10^11 Lsun and 10^11.8 Lsun. We have combined new narrow-band H+[NII]
and broad-band g, r optical imaging taken with the Nordic Optical Telescope
(NOT), with archival GALEX, 2MASS, Spitzer, and Herschel data. The SEDs
(photometry and integrated H flux) have been fitted with a modified
version of the MAGPHYS code using stellar population synthesis models for the
UV-near-IR range and thermal emission models for the IR emission taking into
account the energy balance between the absorbed and re-emitted radiation. From
the SED fits we derive the star-formation histories (SFH) of these galaxies.
For nearly half of them the star-formation rate appears to be approximately
constant during the last few Gyrs. In the other half, the current
star-formation rate seems to be enhanced by a factor of 3-20 with respect to
that occured ~1 Gyr ago. Objects with constant SFH tend to be more massive than
starbursts and they are compatible with the expected properties of a
main-sequence (M-S) galaxy. Likewise, the derived SFHs show that all our
objects were M-S galaxies ~1 Gyr ago with stellar masses between 10^10.1 and
10^11.5 Msun. We also derived from our fits the average extinction (A_v=0.6-3
mag) and the polycyclic aromatic hydrocarbons (PAH) luminosity to L(IR) ratio
(0.03-0.16). We combined the A_v with the total IR and H luminosities
into a diagram which can be used to identify objects with rapidly changing
(increasing or decreasing) SFR during the last 100 Myr.Comment: 16 pages + online material, accepted for publication in A&
A multi-wavelength view of the central kiloparsec region in the Luminous Infrared Galaxy NGC1614
The Luminous Infrared Galaxy NGC1614 hosts a prominent circumnuclear ring of
star formation. However, the nature of the dominant emitting mechanism in its
central ~100 pc is still under debate. We present sub-arcsecond angular
resolution radio, mid-infrared, Pa-alpha, optical, and X-ray observations of
NGC1614, aimed at studying in detail both the circumnuclear ring and the
nuclear region. The 8.4 GHz continuum emission traced by the Very Large Array
(VLA) and the Gemini/T-ReCS 8.7 micron emission, as well as the Pa-alpha line
emission, show remarkable morphological similarities within the star-forming
ring, suggesting that the underlying emission mechanisms are tightly related.
We used an HST/NICMOS Pa-alpha map of similar resolution to our radio maps to
disentangle the thermal free-free and non-thermal synchrotron radio emission,
from which we obtained the intrinsic synchrotron power-law for each individual
region within the central kpc of NGC1614. The radio ring surrounds a relatively
faint, steep-spectrum source at the very center of the galaxy, suggesting that
the central source is not powered by an AGN, but rather by a compact (r < 90
pc) starburst. Chandra X-ray data also show that the central kpc region is
dominated by starburst activity, without requiring the existence of an AGN. We
also used publicly available infrared data to model-fit the spectral energy
distribution of both the starburst ring and a putative AGN in NGC1614. In
summary, we conclude that there is no need to invoke an AGN to explain the
observed bolometric properties of the galaxy.Comment: 13 pages, 7 figures, 5 tables. Accepted for publication in Ap
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