Mass Distribution in Hickson Compact Groups of Galaxies

This study presents the mass distribution for a sample of 18 late-type galaxies in nine Hickson Compact Groups. We used rotation curves from high resolution 2D velocity fields of Fabry-Perot observations and J-band photometry from the 2MASS survey, in order to determine the dark halo and the visible matter distributions. The study compares two halo density profile, an isothermal core-like distribution and a cuspy one. We also compare their visible and dark matter distributions with those of galaxies belonging to cluster and field galaxies coming from two samples: 40 cluster galaxies of Barnes et al (2004) and 35 field galaxies of Spano et al. (2008). The central halo surface density is found to be constant with respect to the total absolute magnitude similar to what is found for the isolated galaxies. This suggests that the halo density is independent to galaxy type and environment. We have found that core-like density profiles fit better the rotation curves than cuspy-like ones. No major differences have been found between field, cluster and compact group galaxies with respect to their dark halo density profiles.Comment: 35 pages, 21 figures. Accept for publication in Astronomical Journa

GHASP: an H{\alpha} kinematic survey of spiral and irregular galaxies -- IX. The NIR, stellar and baryonic Tully-Fisher relations

We studied, for the first time, the near infrared, stellar and baryonic Tully-Fisher relations for a sample of field galaxies taken from an homogeneous Fabry-Perot sample of galaxies (the GHASP survey). The main advantage of GHASP over other samples is that maximum rotational velocities were estimated from 2D velocity fields, avoiding assumptions about the inclination and position angle of the galaxies. By combining these data with 2MASS photometry, optical colors, HI masses and different mass-to-light ratio estimators, we found a slope of 4.48\pm0.38 and 3.64\pm0.28 for the stellar and baryonic Tully-Fisher relation, respectively. We found that these values do not change significantly when different mass-to-light ratios recipes were used. We also point out, for the first time, that rising rotation curves as well as asymmetric rotation curves show a larger dispersion in the Tully-Fisher relation than flat ones or than symmetric ones. Using the baryonic mass and the optical radius of galaxies, we found that the surface baryonic mass density is almost constant for all the galaxies of this sample. In this study we also emphasize the presence of a break in the NIR Tully-Fisher relation at M(H,K)\sim-20 and we confirm that late-type galaxies present higher total-to-baryonic mass ratios than early-type spirals, suggesting that supernova feedback is actually an important issue in late-type spirals. Due to the well defined sample selection criteria and the homogeneity of the data analysis, the Tully-Fisher relation for GHASP galaxies can be used as a reference for the study of this relation in other environments and at higher redshifts.Comment: 16 pages, 6 figures. Accepted for publication in MNRA

Kinematics and morphology of ionized gas in Hickson Compact Group 18

We present new observations of $H\alpha$ emission in the Hickson Compact Group 18 (HCG 18) obtained with a scanning Fabry-Perot interferometer. The velocity field does not show motions of individual group members but, instead, a complex common velocity field for the whole group. The gas distribution is very asymmetric with clumps of maximum intensity coinciding with the optically brightest knots. Comparing $H\alpha$ and HI data we conclude that HCG 18 is not a compact group but instead a large irregular galaxy with several clumps of star formation.Comment: Accepted for publication in Astronomical Journal (13p 6 figures

Kinematics of galaxies in Compact Groups. Studying the B-band Tully-Fisher relation

We obtained new Fabry-Perot data cubes and derived velocity fields, monochromatic and velocity dispersion maps for 28 galaxies in the Hickson compact groups 37, 40, 47, 49, 54, 56, 68, 79 and 93. We find that one third of the non-barred compact group galaxies have position angle misalignments between the stellar and gaseous components. This and the asymmetric rotation curves are clear signatures of kinematic perturbations, probably due to interactions among compact group galaxies. A comparison between the B-band Tully-Fisher relation for compact group galaxies and that for the GHASP field-galaxy sample shows that, despite the high fraction of compact group galaxies with asymmetric rotation curves, these lie on the Tully-Fisher relation defined by galaxies in less dense environments, although with more scatter. This is in agreement with previous results, but now confirmed for a larger sample of 41 galaxies. We confirm the tendency for compact group galaxies at the low-mass end of the Tully-Fisher relation (HCG 49b, 89d, 96c, 96d and 100c) to have either a magnitude that is too bright for its mass (suggesting brightening by star formation) and/or a low maximum rotational velocity for its luminosity (suggesting tidal stripping). These galaxies are outside the Tully Fisher relation, at the 1 sigma level, even when the minimum acceptable values of inclinations are used to compute their maximum velocities. The inclusion of such galaxies with v<100 km/s in the determination of the zero point and slope of the compact group B-band Tully-Fisher relation would strongly change the fit, making it different from the relation for field galaxies, a fact that has to be kept in mind when studying scaling relations of interacting galaxies, specially at high redshifts.Comment: 17 figures. Accepted for publication in Astronomy and Astrophysics. Hickson compact groups Fabry-Perot data are available at http://fabryperot.oamp.fr/PerotFabry

A multi-wavelength study of the evolution of Early-Type Galaxies in Groups: the ultraviolet view

ABRIDGED- The UV-optical color magnitude diagram (CMD) of rich galaxy groups is characterised by a well developed Red Sequence (RS), a Blue Cloud (BC) and the so-called Green Valley (GV). Loose, less evolved groups of galaxies likely not virialized yet may lack a well defined RS. This is actually explained in the framework of galaxy evolution. We are focussing on understanding galaxy migration towards the RS, checking for signatures of such a transition in their photometric and morphological properties. We report on the UV properties of a sample of ETGs galaxies inhabiting the RS. The analysis of their structures, as derived by fitting a Sersic law to their UV luminosity profiles, suggests the presence of an underlying disk. This is the hallmark of dissipation processes that still must have a role in the evolution of this class of galaxies. SPH simulations with chemo-photometric implementations able to match the global properties of our targets are used to derive their evolutionary paths through UV-optical CDM, providing some fundamental information such as the crossing time through the GV, which depends on their luminosity. The transition from the BC to the RS takes several Gyrs, being about 3-5 Gyr for the the brightest galaxies and more long for fainter ones, if it occurs. The photometric study of nearby galaxy structures in UV is seriously hampered by either the limited FoV of the cameras (e.g in HST) or by the low spatial resolution of the images (e.g in the GALEX). Current missions equipped with telescopes and cameras sensitive to UV wavelengths, such as Swift-UVOT and Astrosat-UVIT, provide a relatively large FoV and better resolution than the GALEX. More powerful UV instruments (size, resolution and FoV) are obviously bound to yield fundamental advances in the accuracy and depth of the surface photometry and in the characterisation of the galaxy environment.Comment: 12 pages, 6 figures: accepted for publication in Astrophysics & Space Science as contributions to the workshop: "UV astronomy, the needs and the means

Dynamical effects of interactions and the Tully-Fisher relation for Hickson compact groups

We investigate the properties of the B-band Tully-Fisher (T-F) relation for 25 compact group galaxies, using Vmax derived from 2-D velocity maps. Our main result is that the majority of the Hickson Compact Group galaxies lie on the T-F relation. However, about 20% of the galaxies, including the lowest-mass systems, have higher B luminosities for a given mass, or alternatively, a mass which is too low for their luminosities. We favour a scenario in which outliers have been brightened due to either enhanced star formation or merging. Alternatively, the T-F outliers may have undergone truncation of their dark halo due to interactions. It is possible that in some cases, both effects contribute. The fact that the B-band T-F relation is similar for compact group and field galaxies tells us that these galaxies show common mass-to-size relations and that the halos of compact group galaxies have not been significantly stripped inside R25. We find that 75% of the compact group galaxies studied (22 out of 29) have highly peculiar velocity fields. Nevertheless, a careful choice of inclination, position angle and center, obtained from the velocity field, and an average of the velocities over a large sector of the galaxy enabled the determination of fairly well-behaved rotation curves for the galaxies. However, two of the compact group galaxies which are the most massive members in M51--like pairs, HCG 91a and HCG 96a, have very asymmetric rotation curves, with one arm rising and the other one falling, indicating, most probably, a recent perturbation by the small close companions.Comment: 15 pages, 4 figures, accepted for publication in the Astronomical Journa

A Search for the Optical/Infrared Counterpart of the Anomalous X-ray Pulsar 1E 1841-045

We have carried out a search for the optical and infrared counterpart of the Anomalous X-ray Pulsar 1E 1841-045, which is located at the center of the supernova remnant Kes73. We present the first deep optical and infrared images of the field of 1E 1841-045, as well as optical spectroscopy results that exclude the brightest objects in the error circle as possible counterparts. A few of the more reddened objects in this region can be considered as particularly interesting candidates, in consideration of the distance and absorption expected from the association with Kes73. The strong interstellar absorption in the direction of the source does not allow to completely exclude the presence of main sequence massive companions.Comment: 8 pages, latex, 6 figures, Submitted to Mon. Not. R. Astron. So

New insights into the catalytic activity of gold nanoparticles for CO oxidation in electrochemical media

This study reports the interaction between metal oxides and gold in acidic media and its effect on the electrochemical oxidation of carbon monoxide. We describe the oxidation of CO in acidic media on Au nanoparticles of 3 and 7 nm on different oxide supports, diamond and carbon electrodes. In addition, the effect of a TiOx support on Au nanoparticles was mimicked by supporting TiOx nanoparticles on bulk gold. The comparison of these two systems strongly suggests that electronic interactions between Au and TiOx, rather than Au nanoparticle size effects, are the driving force of the catalytic activity in Au–TiOx

Galaxy evolution in nearby groups. II. Galaxy evolution in nearby loose groups. II. Photometric and kinematic characterization of USGC U268 and USGC U376 group members in the Leo cloud

We present the photometric and kinematic characterization of two groups, USGC U268 and USGC U376 located in different regions of the Leo cloud. U268, composed of 10 catalogued members and 11 new added members, has a small fraction (~24%) of early-type galaxies (ETGs). U376 has 16 plus 8 new added members, with ~38% of ETGs. We find the presence of significant substructures in both groups suggesting that they are likely accreting galaxies. U268 is located in a more loose environment than U376. For each member galaxy, broad band integrated and surface photometry have been obtained in far-UV and near-UV with GALEX, and in u,g, r, i, z (SDSS) bands. H_alpha imaging and 2D high resolution kinematical data have been obtained using PUMA Scanning Fabry-Perot interferometer at the 2.12 m telescope in San Pedro M\'artir, (Baja California, M\'exico). We improved the galaxy classification and we detected morphological and kinematical distortions that may be connected to either on-going and/or past interaction/accretion events or environmental induced secular evolution. U268 appears more active than U376, with a large fraction of galaxies showing interaction signatures (60% vs. 13%). The presence of bars among late-type galaxies is ~10% in U268 and ~$29% in U376. The cumulative distribution of (FUV - NUV) colours of galaxies in U268 is significantly different than that in U376 with galaxies in U268 bluer than those in U376. In the (FUV-r vs. M_r) and (NUV-r vs. M_r) planes no members of U268 are found in the `red sequence', even early-type galaxies lie in the `blue sequence' or in the `green valley'. Most (80%) of the early-type members in U376 inhabits the `red sequence, a large fraction of galaxies, of different morphological types, are located in the `green valley', while the `blue sequence' is under-populated with respect to U268.Comment: 27 pages, 11 figures, 8 tables, accepted for publication in MNRAS (abridged abstract

An international prospective general population-based study of respiratory work disability

Background: Previous cross-sectional studies have shown that job change due to breathing problems at the workplace (respiratory work disability) is common among adults of working age. That research indicated that occupational exposure to gases, dust and fumes was associated with job change due to breathing problems, although causal inferences have been tempered by the cross-sectional nature of previously available data. There is a need for general population-based prospective studies to assess the incidence of respiratory work disability and to delineate better the roles of potential predictors of respiratory work disability.Methods: A prospective general population cohort study was performed in 25 centres in 11 European countries and one centre in the USA. A longitudinal analysis was undertaken of the European Community Respiratory Health Survey including all participants employed at any point since the baseline survey, 6659 subjects randomly sampled and 779 subjects comprising all subjects reporting physician-diagnosed asthma. The main outcome measure was new-onset respiratory work disability, defined as a reported job change during follow-up attributed to breathing problems. Exposure to dusts (biological or mineral), gases or fumes during follow-up was recorded using a job-exposure matrix. Cox proportional hazard regression modelling was used to analyse such exposure as a predictor of time until job change due to breathing problems.Results: The incidence rate of respiratory work disability was 1.2/1000 person-years of observation in the random sample (95% CI 1.0 to 1.5) and 5.7/1000 person-years in the asthma cohort (95% CI 4.1 to 7.8). In the random population sample, as well as in the asthma cohort, high occupational exposure to biological dust, mineral dust or gases or fumes predicted increased risk of respiratory work disability. In the random sample, sex was not associated with increased risk of work disability while, in the asthma cohort, female sex was associated with an increased disability risk (hazard ratio 2.8, 95% CI 1.3 to 5.9).Conclusions: Respiratory work disability is common overall. It is associated with workplace exposures that could be controlled through preventive measures