479 research outputs found
Integral Field Spectroscopy of the inner kpc of the elliptical galaxy NGC 5044
We used Gemini Multi-Object Spectrograph (GMOS) in the Integral Field Unit
mode to map the stellar population, emission line flux distributions and gas
kinematics in the inner kpc of NGC 5044. From the stellar populations synthesis
we found that the continuum emission is dominated by old high metallicity stars
(13 Gyr, 2.5Z). Also, its nuclear emission is diluted by a non
thermal emission, which we attribute to the presence of a weak active galactic
nuclei (AGN). In addition, we report for the first time a broad component
(FWHM 3000km) in the H emission line in the nuclear
region of NGC 5044. By using emission line ratio diagnostic diagrams we found
that two dominant ionization processes coexist, while the nuclear region (inner
200 pc) is ionized by a low luminosity AGN, the filamentary structures are
consistent with being excited by shocks. The H velocity field shows
evidence of a rotating disk, which has a velocity amplitude of
240kms at 136 pc from the nucleus. Assuming a Keplerian
approach we estimated that the mass inside this radius is
, which is in agreement with the value obtained through the
M- relation, . Modelling the
ionized gas velocity field by a rotating disk component plus inflows towards
the nucleus along filamentary structures, we obtain a mass inflow rate of
0.4 M. This inflow rate is enough to power the central AGN in NGC
5044.Comment: 16 pages, 12 figures, accepted by MNRA
Azimuthal variations of oxygen abundance profiles in star-forming regions of disc galaxies in EAGLE simulations
The exploration of the spatial distribution of chemical abundances in star-forming regions
of galactic discs can help us to understand the complex interplay of physical processes that
regulate the star formation activity and the chemical enrichment across a galaxy. We study the
azimuthal variations of the normalized oxygen abundance profiles in the highest numerical
resolution run of the Evolution and Assembly of GaLaxies and their Environments (EAGLE)
Project at z = 0. We use young stellar populations to trace the abundances of star-forming
regions. Oxygen profiles are estimated along different line of sights from a centrally located
observer. The mean azimuthal variation in the EAGLE discs are ∼0.12 ± 0.03 dex R−1
eff for
slopes and ∼0.12 ± 0.03 dex for the zero-points, in agreement with previous works. Metallicity
gradients measured along random directions correlate with those determined by averaging over
the whole discs, although with a large dispersion. We find a slight trend for higher azimuthal
variations in the disc components of low star-forming and bulge-dominated galaxies. We
also investigate the metallicity profiles of stellar populations with higher and lower levels of
enrichment than the average metallicity profiles, and we find that high star-forming regions with
high metallicity tend to have slightly shallower metallicity slopes compared with the overall
metallicity gradient. The simulated azimuthal variations in the EAGLE discs are in agreement
with observations, although the large variety of metallicity gradients would encourage further
exploration of the metal mixing in numerical simulations.Indexación: Scopu
PelÃculas pasivantes protectora de óxido/carbonato de cinc en la zona splash de estructuras metálicas de acero al carbón
PelÃculas pasivantes con zinctape® fueron inducidas, sobre estructuras de acero al carbón de un muelle expuesto en ambiente salino y aireación diferencial, el brazo de descarga, con elevado desgaste mecánico y los pilotes de soporte, fueron limpiados con ultra alta presión y realizadas soldaduras tipo cañuelas (casquetes) para reconstruir las zonas perdidas. Las columnas fueron protegidas con zinctape® desde la zona de splash hacia arriba, con un cinta de cinc de 100 mm de ancho, espesor de la capa de cinc 0,08mm, espesor de adhesivo electro conductivo de 0,025 mm. Paralelamente fue habilitado el sistema de protección catódica con corriente impresa. Las estructuras fueron rehabilitadas en un 100% por acción conjunta de los dos métodos de protección. Uno quÃmico al inducir con la cinta, la  formación de una capa delgada, resistente, compacta y estable (insoluble en agua) del carbonato de cinc y  otro fisicoquÃmico como corriente impresa. Esta mitologÃa es amigable con el medio ambiente y económicamente rentable, con una duración asegurada de mÃnimo 10 años
Exploring the AGN-Merger Connection in Arp 245 I: Nuclear Star Formation and Gas Outflow in NGC 2992
Galaxy mergers are central to our understanding of galaxy formation,
especially within the context of hierarchical models. Besides having a large
impact on the star formation history, mergers are also able to influence gas
motions at the centre of galaxies and trigger an Active Galactic Nucleus (AGN).
In this paper, we present a case study of the Seyfert galaxy NGC 2992, which
together with NGC 2993 forms the early-stage merger system Arp 245. Using
Gemini Multi-Object Spectrograph (GMOS) integral field unit (IFU) data from the
inner 1.1 kpc of the galaxy we were able to spatially resolve the stellar
populations, the ionisation mechanism and kinematics of ionised gas. From full
spectral synthesis, we found that the stellar population is primarily composed
by old metal-rich stars (t 1.4 Gyr, \zsun), with a
contribution of at most 30 per cent of the light from a young and metal-poor
population (t 100 Myr, \zsun). We detect \halpha and \hbeta
emission from the Broad Line Region (BLR) with a Full Width at Half Maximum
(FWHM) of 2000\kms. The Narrow Line Region (NLR) kinematics presents two
main components: one from gas orbiting the galaxy disk and a blueshifted
(velocity -200\kms) outflow, possibly correlated with the radio
emission, with mass outflow rate of 2 M yr and a
kinematic power of 2 erg s (\Eout/\Lbol
0.2 per cent). We also show even though the main ionisation mechanism
is the AGN radiation, ionisation by young stars and shocks may also contribute
to the emission line ratios presented in the innermost region of the galaxy.Comment: 20 pages, 13 Figs, Accepted for publication to the MNRA
Galaxy evolution in compact groups I: Revealing a transitional galaxy population through a multiwavelength approach
Compact groups of galaxies (CGs) show members with morphological
disturbances, mainly products of galaxy-galaxy interactions, thus making them
ideal systems to study galaxy evolution, in high-density environment. To
understand how this environment affects the properties of galaxies, we select a
sample of 340 CGs in the Stripe 82 region, for a total of 1083 galaxies, and a
sample of 2281 field galaxies as a control sample. By performing a
multi-wavelength morphological fitting process using S-PLUS data, we divide our
sample into early-type (ETG), late-type (LTG), and transition galaxies using
the r-band S\'ersic index and the colour (u-r). We find a bimodal distribution
in the plane of the effective radius-S\'ersic index, where a secondary
"peculiar" galaxy population of smaller and more compact galaxies is found in
CGs, which is not observed in the control sample. This indicates that galaxies
are undergoing a morphological transformation in CGs. In addition, we find
significant statistical differences in the distribution of specific Star
Formation Rate (sSFR) when we compare both environments for LTGs and ETGs. We
also find a higher fraction of quenched galaxies and a lower median sSFR in CGs
than in the control sample, suggesting the existence of environmental effects
favoring the cessation of star formation, regardless of galaxy type. Our
results support the notion that CGs promote morphological and physical
transformations, highlighting their potential as ideal systems for galaxy
pre-processing.Comment: 17 pages, 15 figures. Accepted for publication in MNRA
Shoc2/Sur8 protein regulates neurite outgrowth
This is an openaccess
article distributed under the terms of the
Creative Commons Attribution License.-- et al.The Shoc2 protein has been implicated in the positive regulation of the Ras-ERK pathway by increasing the functional binding interaction between Ras and Raf, leading to increased ERK activity. Here we found that Shoc2 overexpression induced sustained ERK phosphorylation, notably in the case of EGF stimulation, and Shoc2 knockdown inhibited ERK activation. We demonstrate that ectopic overexpression of human Shoc2 in PC12 cells significantly promotes neurite extension in the presence of EGF, a stimulus that induces proliferation rather than differentiation in these cells. Finally, Shoc2 depletion reduces both NGF-induced neurite outgrowth and ERK activation in PC12 cells. Our data indicate that Shoc2 is essential to modulate the Ras-ERK signaling outcome in cell differentiation processes involved in neurite outgrowth.GL, TG and LMD were recipients of fellowships from the Ministerio de Educación y Ciencia (MEC) (to GL, TG), and Fondo de Investigaciones Sanitarias (FIS) (to LMD). LSR
held a postdoctoral research contract from CIBERNED. This work was supported by FIS grant
(PI10/00815) to JLO; CIBERNED to MC; SAF2008-01951, Comunidad Autónoma de Madrid (CAM) SSAL-0202-2006-01 and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) to TI; FIS grant PI12/00775 and ISCIII-RETIC (Red Temática de Investigación Cooperativa en Cáncer) RD12/0036/0027 from the Instituto de Salud Carlos III to PSG; and FIS grants (PI09/0562 and PI13/00703), ISCIIIRETIC
(RD06/0020/0003 and RD12/0036/0021), and the Spanish Association Against Cancer
(AECC) to JMR.Peer Reviewe
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