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We present 170 optical spectra of 35 low-redshift stripped-envelope core-collapse supernovae observed by the Carnegie Supernova Project-I between 2004 and 2009. The data extend from as early as -19 days (d) prior to the epoch of B-band maximum to +322 d, with the vast majority obtained during the so-called photospheric phase covering the weeks around peak luminosity. In addition to histogram plots characterizing the red-shift distribution, number of spectra per object, and the phase distribution of the sample, spectroscopic classification is also provided following standard criteria. The CSP-I spectra are electronically available and a detailed analysis of the data set is presented in a companion paper being the fifth and final paper of the series, Comment: Resubmitted to A&A after address referee's comments. Comments welcomed, and let us know if we missed to reference your paper?

International audience; OBJECTIVE: To report a pilot project of expert nurses for outpatient parenteral antimicrobial treatment (OPAT) follow-up. METHODS: Three nurses with specific training on antibiotics started a state-funded programme including: i) consultations for OPAT follow-up; ii) hotline for satellite hospitals; iii) peer training. Patients’ data were prospectively collected. A representative sample of patients and physicians was interviewed to learn about their opinion on the project. RESULTS: From December 2020 to December 2021, 118 patients (median age 66.5 years [52-75], male-to-female ratio 2.5) were enrolled, for a total of 621 consultations. Patients were mostly on OPAT for bone and joint infections (n = 76, 64 %) and cardiovascular infections (n = 16, 14 %), for a median duration of 29 days [22-57]. Eleven patients (9 %) required unplanned hospital admissions, and three experienced treatment failure. Most patients (21/22) and physicians in charge (10/10) reported a high level of satisfaction. CONCLUSIONS: Nurses may be important actors for OPAT follow-up.

As part of the VESTIGE survey, a blind narrow-band Ha+[NII] imaging survey of the Virgo cluster carried out with MegaCam at the CFHT, we discovered 8 massive lenticular galaxies with prominent ionised gas emission features in their inner (few kpc) regions. These features are either ionised gas filaments similar to those observed in cooling flows (2 gal), or thin discs with sizes 0.7, Comment: Accepted for publication on A&A

We use continuous-wave excitation of a single molecule to measure the full temporal wavepacket indistinguishability of emitted photons, and show that continuous-wave light can determine the coupling of quantum emitters to arbitrary nanophotonic structures.

Low-surface-brightness galaxies (LSBs) contribute to a significant fraction of all the galaxies in the Universe. Ultra-diffuse galaxies (UDGs) form a subclass of LSBs that has attracted a lot of attention in recent years (although its definition may vary between studies). Although UDGs are found in large numbers in galaxy clusters, groups, and in the field, their formation and evolution are still very much debated. Using a comprehensive set of multiwavelength data from the NGVS (optical), VESTIGE (H$\alpha$ narrowband), and GUViCS (UV) surveys, we studied a sample of 64 diffuse galaxies and UDGs in the Virgo cluster to investigate their formation history. We analyzed the photometric colors and surface-brightness profiles of these galaxies and then compared them to models of galaxy evolution, including ram-pressure stripping (RPS) events to infer any possible strong interactions with the hot cluster gas in the past. While our sample consists mainly of red LSBs, which is typical in cluster environments, we found evidence of a color variation with the cluster-centric distance. Blue, HI-bearing, star-forming diffuse galaxies are found at larger distances from the cluster center than the rest of the sample. The comparison of our models with multifrequency observations suggests that most of the galaxies of the sample might have undergone a strong RPS event in their lifetime, on average 1.6 Gyr ago (with a large dispersion, and RPS still ongoing for some of them). This process resulted in the transformation of initially gas-rich diffuse blue galaxies into gas-poor and red ones that form the dominant population now, the more extreme UDGs having undergone the process in a more distant past on average. The RPS in dense environments could be one of the major mechanisms for the formation of the large number of quiescent UDGs we observe in galaxy clusters., Comment: 57 pages, 14 Figures, accepted for publication in A&A

Introduction Le bon usage des antibiotiques (ATB) est essentiel pour lutter contre l’antibioresistance, et limiter leurs effets secondaires. A l’hopital, la place de l’infirmier diplome d’etat (IDE) est centrale dans l’execution des prescriptions, la surveillance des ATB, la securite des soins, et la transmission des informations au patient et au medecin. Nous decrivons les difficultes rencontrees dans la mise en oeuvre des prescriptions d’ATB par les IDE au sein d’un CHU de 1500 lits de MCO. Materiels et methodes Il s’agit d’une enquete observationnelle, monocentrique, d’evaluation des pratiques infirmieres par questionnaire a reponses multiples ; des IDE de specialites medicochirurgicales adultes, en dehors des services de reanimation et d’obstetrique ont ete sollicites. Deux cents questionnaires ont ete diffuses dans 20 services (12 de medecine, 8 de chirurgie), et 40 aux urgences. Resultats Un total de 131 (54 %) questionnaires ont ete completes : 59 en medecine, 46 en chirurgie et 26 aux urgences. Tous les repondants declarent utiliser des antibiotiques, quotidiennement pour 66 % d’entre eux. La prescription medicale est jugee insuffisante pour l’administration des ATB en toute securite pour 54 % (71/131) des soignants, tous services confondus, et jusqu’a 77 % (20/26) aux urgences. Les informations faisant defaut dans la prescription sont rapportees par 84 soignants : elles concernent la reconstitution de l’ATB pour 56 IDE, la dilution pour 70, les modalites de perfusion pour 47 et la duree de perfusion chez 45. Dans tous les services, pres de 80 % (101/130) des IDE declarent connaitre certains des effets indesirables des ATB, en majorite les troubles digestifs (115/128, 90 %) et cutanes (122/128, 95 %). Les effets secondaires graves sont connus a seulement 30 % (39/128) pour la dyspnee, 30 % (39/128) pour l’hypotension et 46 % (59/128) pour le malaise. Les IDE des urgences sont plus sensibilises a ces effets indesirables severes (18/26, 69 %). L’organisation de la sortie d’un patient sous ATB est source de difficultes pour 45 % (55/122) des soignants. Les problematiques recensees par 62 soignants sont diverses : modalites de retrocession (n = 34), d’administration (n = 26), et de surveillance du patient (n = 27), et meconnaissance des structures exterieures (HAD, prestataires de service ; n = 29). Les IDE sont principalement demandeurs de formations (56 %), de protocoles (71 %) et d’une astreinte infirmiere en infectiologie (30 %). Conclusion Dans tous les services, la prescription medicale des ATB, la surveillance des patients a l’hopital ou la sortie sous anti-infectieux sont problematiques pour une moitie des equipes infirmieres. Cet etat des lieux ouvre des perspectives d’actions pour une securisation des soins et un meilleur usage des ATB : accompagnement des equipes et formation, en favorisant leur autonomie. Un IDE expert en therapeutiques anti-infectieuses pourrait permettre d’optimiser la prise en charge pluridisciplinaire de gestion des ATB.

We present new 2D high resolution Fabry-Perot spectroscopic observations of 152 star-forming galaxies which are part of the $Herschel$ Reference Survey (HRS), a complete $K$-band selected, volume-limited sample of nearby galaxies, spanning a wide range in stellar mass and morphological type. Using improved data reduction techniques that provide adaptive binning based on Voronoi tessellation, using large field-of-view observations, we derive high spectral resolution (R$>$10,000) H$\alpha$ datacubes from which we compute H$\alpha$ maps and radial 2D velocity fields that are based on several thousand independent measurements. A robust method based on such fields allows us to accurately compute rotation curves and kinematical parameters, for which uncertainties are calculated using a method based on the power spectrum of the residual velocity fields. We check the consistency of the rotation curves by comparing our maximum rotational velocities to those derived from HI data, and computing the $i$-band, NIR, stellar and baryonic Tully-Fisher relations. We use this set of kinematical data combined to those available at other frequencies to study for the first time the relation between the dynamical and the total baryonic mass (stars, atomic and molecular gas, metals and dust), and derive the baryonic and dynamical main sequence on a representative sample of the local universe., Comment: 43 pages, 18 figures, 4 tables. The complete version of the tables, figures and all the Fabry-Perot data will be made available online at the CDS, on the HRS dedicated database HeDAM (https://hedam.lam.fr/), and on the Fabry-Perot database (https://cesam.lam.fr/fabryperot)

(Abridged) Long gamma-ray bursts (LGRB) have been suggested as promising tracers of star formation owing to their association with the core-collapse of massive stars. The goal of this work is to characterise the population of host galaxies of LGRBs at 1 < z < 2, investigate the conditions in which LGRBs form at these redshifts and assess their use as tracers of star formation. We perform a spectro-photometric analysis to determine the stellar mass, star formation rate, specific star formation rate and metallicity of the complete, unbiased host galaxy sample of the Swift/BAT6 LGRB sample at 1 < z < 2. We compare the distribution of these properties to the ones of typical star-forming galaxies from the MOSDEF and COSMOS2015 Ultra Deep surveys, within the same redshift range. We find that, similarly to z < 1, LGRBs do not directly trace star formation at 1 < z < 2, and they tend to avoid high-mass, high-metallicity host galaxies. We also find evidence for an enhanced fraction of starbursts among the LGRB host sample with respect to the star-forming population of galaxies. Nonetheless we demonstrate that the driving factor ruling the LGRB efficiency is metallicity. The LGRB host distributions can be reconciled with the ones expected from galaxy surveys by imposing a metallicity upper limit of 12+logOH ~ 8.55. Metallicity rules the LGRB production efficiency, which is stifled at Z > 0.7 Zsun. Under this hypothesis we can expect LGRBs to trace star formation at z > 3, once the bulk of the star forming galaxy population are characterised by metallicities below this limit. The moderately high metallicity threshold found is in agreement with the conditions necessary to rapidly produce a fast-rotating Wolf-Rayet star a in close binary system, and could be accommodated by single star models under chemically homogeneous mixing with very rapid rotation and weak magnetic coupling., Comment: 19 pages, 17 figures, accepted for publication in Astronomy & Astrophysics

Introduction L’accompagnement de la personne soignee sous antibiotherapie necessite des competences medicales et paramedicales. De nombreuses lignes telephoniques d’aide en infectiologie sont destinees aux prescripteurs. La reponse est incomplete voire absente face au questionnement infirmier. Nous avons interroge les equipes infirmieres des soins de suite et de readaptation, et des hopitaux de proximite au sein du groupement des hopitaux territoriaux sur les difficultes rencontrees pour le traitement antibiotique des patients transferes d’un CHU. Nous souhaitions aussi definir la place que pourrait occuper un infirmier diplome d’Etat specialise en therapeutiques anti-infectieuses afin de repondre aux demandes des equipes. Materiels et methodes Un questionnaire papier destine aux IDE a ete distribue au printemps 2019 aupres de quatre etablissements du GHT dans des unites de medecine et SSR. Dix-huit questions fermees, ouvertes ou a choix multiples etaient proposees pour determiner les caracteristiques des repondants, les difficultes rencontrees en antibiotherapie, les ressources, la formation continue et les attentes des IDE. Resultats Vingt-quatre questionnaires ont ete analyses. L’experience des repondants allait de 1 a 32 ans d’exercice. Les principales difficultes etaient : les modalites d’administration (n = 11, 52 %), la connaissance des antibiotiques et leurs effets indesirables (n = 11, 52 %), les modalites de delivrance (n = 8, 38 %), la surveillance des voies veineuses (n = 7, 33 %) et les prescriptions medicales imprecises (n = 7, 33 %). L’absence de consultation de suivi specialisee etait rapportee par treize repondants (54 %). Les ressources des professionnels etaient : l’echange au sein de l’equipe (n = 18, 75 %), le recours a un referent infectieux de la structure (n = 15, 62 %), les documents intranet de l’etablissement (n = 13, 54 %), Internet (n = 10, 42 %) et l’equipe de l’unite de maladies infectieuses du CHU (n = 8, 33 %). Le principal frein pour un recours a l’equipe du CHU etait le temps d’attente telephonique. Seuls huit IDE ont beneficie d’une formation a la gestion des PICC line (33 %). Dix-neuf IDE etaient favorables a une ligne d’avis infectiologique infirmier (79 %), essentiellement par telephone (n = 11, 61 %) ou mail (n = 7, 38 %). Conclusion La complexite de certaines antibiotherapies met en difficulte les equipes non specialisees recevant les patients suite a une hospitalisation en CHU. Paradoxalement, les IDE specialises au sein du CHU sont relativement peu sollicites compte tenu des problematiques rapportees. Un IDE expert en therapeutiques anti-infectieuses pourrait repondre a cette demande par une ligne d’avis dediee soit par telephone ou par mail. Ce soutien pourrait limiter le sentiment de defaut de suivi exprime par les equipes paramedicales de SSR et des hopitaux de proximite.

Introduction Le dossier medical partage (DMP) permet de centraliser les informations medicales et paramedicales utiles a la prise en charge d’un patient. Il participe a l’echange d’informations entre professionnels de sante et le patient. Il pourrait etre ainsi un outil particulierement utile dans le suivi des patients traites par anti-infectieux de facon prolongee. Trois infirmieres (IDE) rennaises ont obtenu un diplome universitaire de therapeutiques anti-infectieuses pour les paramedicaux et assurent un role d’expert infirmier. A partir d’une enquete preliminaire interrogeant des professionnels sur l’interet du suivi par un IDE des patients grâce au DMP, nous definissions le role d’infirmier expert. Materiels et methodes Douze professionnels ont repondu : 3 IDE hospitalieres, 1 IDE liberal, 2 IDE de prestataires de service, 2 medecins generalistes liberaux, 4 medecins infectiologues hospitaliers. Etaient questionnes les attentes et interets potentiels du suivi par un IDE expert des patients necessitant un traitement anti-infectieux prolonge et la place du DMP dans ce suivi. Resultats Cinq pathologies arrivent en tete en termes d’infections qui pourraient beneficier du DMP renseigne par un IDE expert : l’endocardite, le VIH, la tuberculose, les infections sexuellement transmissibles (IST) et les infections osteoarticulaires. La sequence de soins pourrait etre : – durant l’hospitalisation initiale, synthese medico-soignante realisee par l’IDE et le patient dans le DMP en complement du courrier d’hospitalisation plus detaille, retracant les traitements administres, la voie d’abord utilisee avec ses eventuelles difficultes d’utilisation, les examens complementaires a venir, les rendez-vous de suivis ; – a la sortie, message systematique adresse par l’IDE au medecin traitant signalant les informations mentionnees dans le DMP, transmissions avec les equipes IDE liberales ou les prestataires de service si necessaire ; – durant le suivi ambulatoire, pour les patients sous antibiotherapie parenterale : teleconsultation et consultations au domicile ou a l’hopital par l’IDE pour le suivi therapeutique, surveillance voie d’abord, prelevements sanguins, releves des effets secondaires avec synthese effectuee avec le patient, suivi des resultats biologiques ; – en fin de suivi : synthese effectuee avec le patient. Conclusion Avec 7 millions de dossiers deja ouverts, le DMP devient un outil majeur pour le suivi des patients atteints de maladies chroniques. Pour les maladies infectieuses, son utilisation par le patient, aide d’un IDE expert, permettrait d’ameliorer la qualite des soins en ambulatoire, y compris pour ceux recevant des traitements lourds a domicile. Cet usage renforcerait le patient acteur de sa prise en charge et securiserait les soins par un suivi specialise.

Context. At low redshift, early-type galaxies often exhibit a rising flux with decreasing wavelength in the 1000-2500 Å range, called "UV upturn". The origin of this phenomenon is debated, and its evolution with redshift is poorly constrained. The observed GALEX FUV-NUV color can be used to probe the UV upturn approximately to redshift 0.5. Aim. We provide constraints on the existence of the UV upturn up to redshift 0.4 in the brightest cluster galaxies (BCG) located behind the Virgo cluster, using data from the GUViCS survey. Methods: We estimate the GALEX far-UV (FUV) and near-UV (NUV) observed magnitudes for BCGs from the maxBCG catalog in the GUViCS fields. We increase the number of nonlocal galaxies identified as BCGs with GALEX photometry from a few tens of galaxies to 166 (64 when restricting this sample to relatively small error bars). We also estimate a central color within a 20 arcsec aperture. By using the r-band luminosity from the maxBCG catalog, we can separate blue FUV-NUV due to recent star formation and candidate upturn cases. We use Lick indices to verify their similarity to redshift 0 upturn cases. Results: We clearly detect a population of blue FUV-NUV BCGs in the redshift range 0.10-0.35, vastly improving the existing constraints at these epochs by increasing the number of galaxies studied, and by exploring a redshift range with no previous data (beyond 0.2), spanning one more Gyr in the past. These galaxies bring new constraints that can help distinguish between assumptions concerning the stellar populations causing the UV upturn phenomenon. The existence of a large number of UV upturns around redshift 0.25 favors the existence of a binary channel among the sources proposed in the literature. Tables 2-5 are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/611/A42

Aims. We investigate the existence of a metallicity threshold for the production of long gamma-ray bursts (LGRBs). Methods. We used the host galaxies of the Swift/BAT6 sample of LGRBs. We considered the stellar mass, star formation rate (SFR), and metallicity determined from the host galaxy photometry and spectroscopy up to z = 2 and used them to compare the distribution of host galaxies to that of field galaxies in the mass-metallicity and fundamental metallicity relation plane. Results. We find that although LGRBs also form in galaxies with relatively large stellar masses, the large majority of host galaxies have metallicities below log (O/H) ~ 8.6. The extension to z = 2 results in a good sampling of stellar masses also above Log(M∗/M⊙) ~ 9.5 and provides evidence that LGRB host galaxies do not follow the fundamental metallicity relation. As shown by the comparison with dedicated numerical simulations of LGRB host galaxy population, these results are naturally explained by the existence of a mild (~0.7 Z⊙) threshold for the LGRB formation. The present statistics does not allow us to discriminate between different shapes of the metallicity cutoff, but the relatively high metallicity threshold found in this work is somewhat in disagreement to most of the standard single-star models for LGRB progenitors.

We use Halpha and FUV GALEX data for a large sample of nearby objects to study the high mass star formation activity of normal late-type galaxies. The data are corrected for dust attenuation using the most accurate techniques at present available, namely the Balmer decrement and the total far-infrared to FUV flux ratio. The sample shows a highly dispersed distribution in the Halpha to FUV flux ratio indicating that two of the most commonly used star formation tracers give star formation rates with uncertainties up to a factor of 2-3. The high dispersion is due to the presence of AGN, where the UV and the Halpha emission can be contaminated by nuclear activity, highly inclined galaxies, for which the applied extinction corrections are probably inaccurate, or starburst galaxies, where the stationarity in the star formation history required for transforming Halpha and UV luminosities into star formation rates is not satisfied. Excluding these objects we reach an uncertainty of ~50% on the SFR. The Halpha to FUV flux ratio increases with their total stellar mass. If limited to normal star forming galaxies, however, this relationship reduces to a weak trend that might be totally removed using different extinction correction recipes. In these objects the Halpha to FUV flux ratio seems also barely related with the FUV-H colour, the H band effective surface brightness, the total star formation activity and the gas fraction. The data are consistent with a Kroupa and Salpeter initial mass function in the high mass stellar range and imply, for a Salpeter IMF, that the variations of the slope cannot exceed 0.25, from g=2.35 for massive galaxies to g=2.60 in low luminosity systems. We show however that these observed trends, if real, can be due to the different micro history of star formation in massive galaxies with respect to dwarf.

We study the chemical evolution of the disks of the Milky Way (MW) and of Andromeda (M31), in order to reveal common points and differences between the two major galaxies of the Local group. We use a large set of observational data for M31, including recent observations of the Star Formation Rate (SFR) and gas profiles, as well as stellar metallicity distributions along its disk. We show that, when expressed in terms of the corresponding disk scale lengths, the observed radial profiles of MW and M31 exhibit interesting similarities, suggesting the possibility of a description within a common framework. We find that the profiles of stars, gas fraction and metallicity of the two galaxies, as well as most of their global properties, are well described by our model, provided the star formation efficiency in M31 disk is twice as large as in the MW. We show that the star formation rate profile of M31 cannot be fitted with any form of the Kennicutt-Schmidt law (KS Law) for star formation. We attribute those discrepancies to the fact that M31 has undergone a more active star formation history, even in the recent past, as suggested by observations of a "head-on" collision with the neighboring M32 galaxy about 200 Myr ago. The MW has most probably undergone a quiescent secular evolution, making possible a fairly successful description with a simple model. If M31 is more typical of spiral galaxies, as recently suggested by Hammer et al. (2007), more complex models, involving galaxy interactions, will be required for the description of spirals., 13 Pages, 7 figures, 2 tables, accepted for publication in Astronomy and Astrophysics

The present work is aimed at studying the distribution of galaxies of different types and luminosities along different structural scaling relations to see whether massive and dwarf ellipticals have been shaped by the same formation process. This exercise is here done by comparing the distribution of Virgo cluster massive and dwarf ellipticals and star forming galaxies along the B band effective surface brightness and effective radius vs. absolute magnitude relations and the Kormendy relation to the predictions of models tracing the effects of ram-pressure stripping on disc galaxies entering the cluster environment and galaxy harassment. Dwarf ellipticals might have been formed from low luminosity, late-type spirals that recently entered into the cluster and lost their gas because of a ram-pressure stripping event, stopping their activity of star formation. The perturbations induced by the abrupt decrease of the star formation activity are sufficient to modify the structural properties of disc galaxies into those of dwarf ellipticals. Galaxy harassment induce a truncation of the disc and generally an increase of the effective surface brightness of the perturbed galaxies. The lack of dynamical simulations of perturbed galaxies spanning a wide range in luminosity prevents us to drive any firm conclusion on a possible harassment-induced origin of the low surface brightness dwarf elliptical galaxy population inhabiting the Virgo cluster. Although the observed scaling relations are consistent with the idea that the distribution of elliptical galaxies along the mentioned scaling relation is just due to a gradual variation with luminosity of the Sersic index n, the comparison with models indicates that dwarf ellipticals might have been formed by a totally different process than giant ellipticals

We investigate the dependence of the total-infrared (TIR) to UV luminosity ratio method for calculating the UV dust attenuation A(UV) from the age of the underlying stellar populations by using a library of spectral energy distributions for galaxies with different star formation histories. Our analysis confirms that the TIR/UV vs. A(UV) relation varies significantly with the age of the underlying stellar population: i.e. for the same TIR/UV ratio, systems with low specific star formation rate (SSFR) suffer a lower UV attenuation than starbursts. Using a sample of nearby field and cluster spiral galaxies we show that the use of a standard (i.e. age independent) TIR/UV vs. A(UV) relation leads to a systematic overestimate up to 2 magnitudes of the amount of UV dust attenuation suffered by objects with low SSFR and in particular HI-deficient star forming cluster galaxies. This result points out that the age independent $TIR/UV$ vs. $A(UV)$ relation cannot be used to study the UV properties of large samples of galaxies including low star-forming systems and passive spirals. Therefore we give some simple empirical relations from which the UV attenuation can be estimated taking into account its dependence on the age of the stellar populations, providing a less biased view of UV properties of galaxies.

International audience; We analyze the stellar kinematics of 39 dwarf early-type galaxies (dEs) in the Virgo Cluster. Based on the specific stellar angular momentum lambda(Re) and the ellipticity, we find 11 slow rotators and 28 fast rotators. The fast rotators in the outer parts of the Virgo Cluster rotate significantly faster than fast rotators in the inner parts of the cluster. Moreover, 10 out of the 11 slow rotators are located in the inner 3 degrees (D \textless 1 Mpc) of the cluster. The fast rotators contain subtle disk-like structures that are visible in high-pass filtered optical images, while the slow rotators do not exhibit these structures. In addition, two of the dEs have kinematically decoupled cores and four more have emission partially filling in the Balmer absorption lines. These properties suggest that Virgo Cluster dEs may have originated from late-type star-forming galaxies that were transformed by the environment after their infall into the cluster. The correlation between lambda(Re) and the clustercentric distance can be explained by a scenario where low luminosity star-forming galaxies fall into the cluster, their gas is rapidly removed by ram-pressure stripping, although some of it can be retained in their core, their star formation is quenched but their stellar kinematics are preserved. After a long time in the cluster and several passes through its center, the galaxies are heated up and transformed into slow rotating dEs.

We present new Halpha+[NII] imaging data of late-type galaxies in the Herschel Reference Survey aimed at studying the star formation properties of a K-band-selected, volume-limited sample of nearby galaxies. The Halpha+[NII] data are corrected for [NII] contamination and dust attenuation using different recipes based on the Balmer decrement and the 24mic luminosities. We show that the L(Halpha) derived with different corrections give consistent results only whenever the uncertainty on the estimate of the Balmer decrement is, Accepted for publication on A&A

We present Galaxy Evolution Explorer (GALEX) far-UV and near-UV mosaic observations covering the entirety of M31 and M33. For both targets, we measure the decline of surface brightness (in FUV and NUV) and changes in FUV--NUV color as a function of galactocentric radius. These UV radial profiles are compared to the distribution of ionized gas traced by H-alpha emission. We find that the extent of the UV emission, in both targets, is greater than the extent of the observed HII regions and diffuse ionized gas. We determine the ultraviolet diffuse fraction in M33 using our FUV observations and compare it to the H-alpha diffuse fraction obtained from wide-field narrow-band imaging. The FUV diffuse fraction appears to be remarkably constant near 0.65 over a large range in galactocentric radius, with departures to higher values in circumnuclear regions and, most notably, at the limit of the H-alpha disk. We suggest that the increase in FUV diffuse fraction at large galactocentric radii could indicate that a substantial portion of the diffuse emission beyond this point is not generated in situ but rather scattered from dust, after originating in the vicinity of the disk's outermost HII regions. Radial variation of the H-alpha diffuse fraction was also measured. We found the H-alpha diffuse fraction generally near 0.4 but rising toward the galaxy center, up to 0.6. We made no attempt to correct our diffuse fraction measurements for position-dependent extinction, so the quoted values are best interpreted as upper limits given the plausibly higher extinction for stellar clusters relative to their surroundings.

We show that simple models of the chemical and spectrophotometric evolution of galaxies can be used to explore the properties of present-day galaxies and especially the causes of the observed variety among disc galaxies. We focus on the link between ``classical'' spirals and Low Surface Brightness galaxies.

We present a comparison between the observed properties of damped Lya systems (DLAs) and the predictions of simple models for the evolution of present-day disc galaxies, including both low and high surface brightness galaxies. We focus, in particular, on the number density, column density distribution and gas density of DLAs, which have now been measured in relatively large samples of absorbers. From the comparison we estimate the contribution of present-day disc galaxies to the population of damped Lya systems, and how it varies with redshift. Based on the differences between the models and the observations, we also speculate on the nature of the fraction of DLAs that apparently do not arise in disc galaxies.

Dust depletion plays a key role in understanding the nature of Damped Lyman or systems (DLAs). In this paper we point out a previously unnoticed anticorrelation between the observed abundance ratio [X/Zn] (where Zn is assumed to be undepleted and X stands for the refractories Fe, Cr and Ni) and metal column density ([Zn/H] + log(N-HI)) in DLAs. We suggest that this trend is an unambiguous sign of dust depletion, since metal column density is a measure of the amount of dust along the line of sight. Assuming that DLAs are (proto-) galactic disks and using detailed chemical evolution models with metallicity dependent yields we study chemical evolution and dust depletion patterns for ct and iron-peak elements in DLAs. When observational constraints on the metal column density of DLAs are taken into account las suggested in Boisse et al. 1998) we find that our models reproduce fairly well the observed mild redshift evolution of the abundances of 8 elements (Al, Si, S, Cr, Mn, Fe, Zn and Ni) as well as the observed scatter at a given redshift. By considering the aforementioned dependence of abundance ratios on metal column density, we further explore the general dust depletion pattern in DLAs, comparing to our model results and to a solar reference pattern. We find that for low metal column densities (no depletion), our models compare fairly well to the data, while a solar pattern has difficulties with Mn. At high metal column densities (amount of depletion similar to0.5 dex), the solar pattern describes the data quite well, while our models have difficulties with S. We suggest that further measurements of those key elements, i.e. Zn, S and Mn, will help us to gain more insight into the nature of DLAs. The presently uncertain nucleosynthesis of Zn in massive stars Ion which a large part of these conclusions is based) should be carefully scrutinised.

Assuming that damped Lyman-alpha(DLA) systems are galactic discs, we calculate the corresponding evolution of metal abundances. We use detailed multi-zone models of galactic chemical evolution (reproducing successfully the observed properties of disc galaxies) and appropriate statistics (including geometrical propability factors) to calculate the average metallicity as a function of redshift. The results are compatible with available observations, provided that observational biases are taken into account, as suggested by Boisse et al. (1998). In particular, high column density and high metallicity systems are not detected because the light of backround quasars is severely extinguished, while low column density and low metallicity systems are not detectable through their absorption lines by current surveys. We show that these observational constraints lead to a ``no-evolution'' picture for the DLA metallicity, which does not allow to draw strong conclusions about the nature of those systems or about their role in ``cosmic chemical evolution''.

Long Gamma Ray Bursts (LGRBs) are related to the final stages of evolution of massive stars. As such, they should follow the star formation rate (SFR) of galaxies. We can use them to probe for star-forming galaxies (SFGs) in the distant universe following this assumption. The relation between the rate of LGRBs in a given galaxy and its SFR (that we call the LGRB "bias") may be complex, as we have indications that the LGRB hosts are not perfect analogues to the general population of SFGs. In this work, we try to quantify the dependence of the LGRB bias on physical parameters of their host galaxy such as the SFR or the stellar mass. We propose an empirical method based on the comparison of stellar mass functions (and SFR distributions) of LGRB hosts and of SFGs in order to find how the bias depends on the stellar mass or the SFR. By applying this method to a sample of LGRB hosts at redshifts lower than 1.1, where the properties of SFGs are well established, and where the properties of LGRB host galaxies can be deduced from observations (for stellar masses larger than 10**9.25 Msun and SFR larger than 1.8 Msun / yr), we find that the LGRB bias depends on both the stellar mass and SFR. We find that the bias decreases with the SFR, i.e. we see no preference for highly SFGs, once taken into account the larger number of massive stars in galaxies with larger SFR. We do not find any trend with the specific star formation rate (SSFR) but the dynamical range in SSFR in our study is narrow. Although through an indirect method, we relate these trends to a possible decrease of the LGRBs rate / SFR ratio with the metallicity. The method we propose suggests trends that may be useful to constrain models of LGRB progenitors, showing a clear decrease of the LGRB bias with the metallicity. This is promising for the future as the number of LGRB hosts studied will increase., 9 pages, 5 figures, accepted in A&A

We obtained using MegaCam at the CFHT a deep narrow band Halpha+[NII] wide field image of NGC 4569, the brightest late-type galaxy in the Virgo cluster. The image reveals the presence of long tails of diffuse ionised gas without any associated stellar component extending from the disc of the galaxy up to ~ 80 kpc (projected distance) with a typical surface brightness of a few 10^-18 erg s-1 cm-2 arcsec-2. These features provide direct evidence that NGC 4569 is undergoing a ram presure stripping event. The image also shows a prominent 8 kpc spur of ionised gas associated to the nucleus that spectroscopic data identify as an outflow. With some assumptions on the 3D distribution of the gas, we use the Halpha surface brightness of these extended low surface brightness features to derive the density and the mass of the gas stripped during the interaction of the galaxy with the ICM. The comparison with ad-hoc chemo-spectrophotometric models of galaxy evolution indicates that the mass of the Halpha emitting gas in the tail is comparable to that of the cold phase stripped from the disc, suggesting that the gas is ionised within the tail during the stripping process. The lack of star forming regions suggests that mechanisms other than photoionisation are responsible for the excitation of the gas (shocks, heat conduction, magneto hydrodynamic waves). This analysis indicates that ram pressure stripping is efficient in massive (M_star ~ 10^10.5 Mo) galaxies located in intermediate mass (~ 10^14 Mo) clusters under formation. It also shows that the mass of gas expelled by the nuclear outflow is ~ 1 % than that removed during the ram pressure stripping event. All together these results indicate that ram pressure stripping, rather than starvation through nuclear feedback, can be the dominant mechanism responsible for the quenching of the star formation activity of galaxies in high density environments., Comment: Accepted for publication on Astronomy & Astrophysics

International audience; We study the far infrared (60-500 mu m) colours of late-type galaxies in the Herschel Reference Survey, a K-band selected, volume limited sample of nearby galaxies. The far infrared colours are correlated with each other, with tighter correlations for the indices that are closer in wavelength. We also compare the different colour indices to various tracers of the physical properties of the target galaxies, such as the surface brightness of the ionising and non-ionising stellar radiation, the dust attenuation and the metallicity. The emission properties of the cold dust dominating the far infrared spectral domain are regulated by the properties of the interstellar radiation field. Consistent with that observed in nearby, resolved galaxies, our analysis shows that the ionising and the non-ionising stellar radiation, including that emitted by the most evolved, cold stars, both contribute to the heating of the cold dust component. This work also shows that metallicity is another key parameter characterising the cold dust emission of normal, late-type galaxies. A single modified black body with a grain emissivity index beta = 1.5 better fits the observed SPIRE flux density ratios S 250/S 350 vs. S 350/S 500 than beta = 2, although values of beta similar or equal to 2 are possible in metal rich, high surface brightness galaxies. Values of beta less than or similar to 1.5 better represent metal poor, low surface brightness objects. This observational evidence provides strong constraints for dust emission models of normal, late type galaxies.

Simple models of chemical and spectro-photometric evolution of galaxies allow to study the transformation of galaxies under the influence of e.g. ram pressure in the Virgo cluster (other interactions can also be modeled). With the new data of the large surveys of Virgo in progress (e.g. NGVS in the optical, GUViCS in the UV), we will be able to extend this type of analysis to a large number of galaxies and get a better understanding of the transformation of galaxies in the high density environment.

20 pags., 7 figs., 8 tabs., We present the results from the analysis of optical spectra of 31 Hα-selected regions in the extended UV (XUV) disks of M83 (NGC 5236) and NGC 4625 recently discovered by GALEX. The spectra were obtained using IMACS at the Las Campanas Observatory 6.5 m Magellan I telescope and COSMIC at the Palomar 200 inch (5 m) telescope, respectively, for M83 and NGC 4625. The line ratios measured indicate nebular oxygen abundances (derived from the R23 parameter) of the order of Z⊙/5-Z⊙/10. For most emission-line regions analyzed the line fluxes and ratios measured are best reproduced by models of photoionization by single stars with masses in the range 20-40 M⊙ and oxygen abundances comparable to those derived from the R23 parameter. We find indications for a relatively high N/O abundance ratio in the XUV disk of M83. Although the metallicities derived imply that these are not the first stars formed in the XUV disks, such a level of enrichment could be reached in young spiral disks only 1 Gyr after these first stars would have formed. The amount of gas in the XUV disks allows maintaining the current level of star formation for at least a few Gyr. © 2007. The American Astronomical Society. All rights reserved., GALEX (Galaxy Evolution Explorer) is a NASA Small Explorer, launched in 2003 April. We gratefully acknowledge NASA’s support for construction, operation, and science analysis for the GALEX mission, developed in cooperation with the Centre National d’Etudes Spatiales of France and the Korean Ministry of Science and Technology. A. G. d. P. is financed by the MAGPOP EU Marie Curie Research Training Network and partially by the Spanish Programa Nacional de Astronomıa y Astrofısica under grant AYA2003-01676. telescope.

The ultraviolet-to-radio continuum spectral energy distributions are presented for all 75 galaxies in the Spitzer Infrared Nearby Galaxies Survey (SINGS). A principal component analysis of the sample shows that most of the sample's spectral variations stem from two underlying components, one representative of a galaxy with a low infrared-to-ultraviolet ratio and one representative of a galaxy with a high infrared-to-ultraviolet ratio. The influence of several parameters on the infrared-to-ultraviolet ratio is studied (e.g., optical morphology, disk inclination, far-infrared color, ultraviolet spectral slope, and star formation history). Consistent with our understanding of normal star-forming galaxies, the SINGS sample of galaxies in comparison to more actively star-forming galaxies exhibits a larger dispersion in the infrared-to-ultraviolet versus ultraviolet spectral slope correlation. Early type galaxies, exhibiting low star formation rates and high optical surface brightnesses, have the most discrepant infrared-to-ultraviolet correlation. These results suggest that the star formation history may be the dominant regulator of the broadband spectral variations between galaxies. Finally, a new discovery shows that the 24 micron morphology can be a useful tool for parametrizing the global dust temperature and ultraviolet extinction in nearby galaxies. The dust emission in dwarf/irregular galaxies is clumpy and warm accompanied by low ultraviolet extinction, while in spiral galaxies there is typically a much larger diffuse component of cooler dust and average ultraviolet extinction. For galaxies with nuclear 24 micron emission, the dust temperature and ultraviolet extinction are relatively high compared to disk galaxies., Comment: Accepted for publication in the Astrophysical Journal; Fixed radio flux density units (mJy)

This work presents the main ultraviolet (UV) and far-infrared (FIR) properties of two samples of nearby galaxies selected from the GALEX ($\lambda = 2315$\AA, hereafter NUV) and IRAS ($\lambda = 60\mu$m) surveys respectively. They are built in order to get detection at both wavelengths for most of the galaxies. Star formation rate (SFR) estimators based on the UV and FIR emissions are compared. Systematic differences are found between the SFR estimators for individual galaxies based on the NUV fluxes corrected for dust attenuation and on the total IR luminosity. A combined estimator based on NUV and IR luminosities seems to be the best proxy over the whole range of values of SFR. Although both samples present similar average values of the birthrate parameter b, their star-formation-related properties are substantially different: NUV-selected galaxies tend to show larger values of $b$ for lower masses, SFRs and dust attenuations, supporting previous scenarios for the star formation history (SFH). Conversely, about 20% of the FIR-selected galaxies show high values of $b$, SFR and NUV attenuation. These galaxies, most of them being LIRGs and ULIRGs, break down the downsizing picture for the SFH, however their relative contribution per unit volume is small in the local Universe. Finally, the cosmic SFR density of the local Universe is estimated in a consistent way from the NUV and IR luminosities., Comment: 43 pages, 13 figures, accepted for publication in Astrophysical Journal Supplement Series

Recent far-UV (FUV) and near-UV (NUV) observations of the nearby galaxy NGC4625 made by the Galaxy Evolution Explorer (GALEX) show the presence of an extended UV disk reaching 4 times the optical radius of the galaxy. The UV-to-optical colors suggest that the bulk of the stars in the disk of NGC4625 are currently being formed, providing a unique opportunity to study today the physics of star formation under conditions similar to those when the normal disks of spiral galaxies like the Milky Way first formed. In the case of NGC4625, the star formation in the extended disk is likely to be triggered by interaction with NGC4618 and possibly also with the newly discovered galaxy NGC4625A. The positions of the FUV complexes in the extended disk coincide with peaks in the H I distribution. The masses of these complexes are in the range 10^3-10^4 Msun with their Halpha emission (when present) being dominated by ionization from single stars., 12 pages, 4 figures, accepted for publication in ApJL

We use the far-UV (FUV) and near-UV images of M83 obtained by the Galaxy Evolution Explorer (GALEX) to compute the radial profile of the UV spectral slope in the star-forming disk. We briefly present a model of its chemical evolution, which allows us to obtain realistic intrinsic properties of the stellar populations. Using corollary data, we also compute the profiles of Hα/Hβ and total-IR/FUV ratios. Both the data and model are used to estimate and compare the extinction gradients at the FUV wavelength obtained from these various indicators. We discuss the implications for the determination of the star formation rate.

We compare the dust attenuation properties of two samples of galaxies purely selected in the near-ultraviolet (NUV) band (1750-2750 A, lambda_m = 2310 A) and in the far-infrared (FIR) at 60micron. These samples are built using the GALEX and IRAS sky surveys over ~600 square degrees. The NUV selected sample contains 95 galaxies detected down to NUV=16mag (AB system). 83 galaxies in this sample are spirals or irregulars and only two of them are not detected at 60micron. The FIR selected sample is built from the IRAS PSCz catalog complete down to 0.6Jy. Among the 163 sources, we select 118 star forming galaxies well measured by IRAS, all but 1 are detected in NUV and 14 galaxies are not detected in the far-ultraviolet (FUV) band (1350-1750 A, lambda_m = 1530 A). The dust to ultraviolet (NUV and FUV) flux ratio is calibrated to estimate the dust attenuation at both wavelengths. The median value of the attenuation in NUV is found to be ~1 mag for the NUV selected sample versus ~2 mag for the FIR selected one. Within both samples, the dust attenuation is found to correlate with the luminosity of the galaxies. Almost all the NUV selected galaxies and 2/3 of the FIR selected sample exhibit a lower dust attenuation than that expected from the tight relation found previously for starburst galaxies between the dust attenuation and the slope of the ultraviolet continuum. The situation is inverse for one third of the FIR selected galaxies: their extinction is higher than that deduced from their FUV-NUV color and the relation valid for starbursts., Comment: This paper will be published as part of the Galaxy Evolution Explorer (GALEX) Astrophysical Journal Letters Special Issue

We have used UV (FOCA) and FIR (IRAS) images of six nearby late type galaxies to study the radial variation of the UV extinction (deduced from the FIR/UV ratio). We compare the UV extinction gradient with other extinction indicators (Balmer decrement) and search for a relation between the extinction, the metallicity and the gas surface density among our galaxies. We detect in our small sample a clear relation between extinction and metallicity. These observed relations are used to calibrate an empirical recipe useful for extinction correction in the UV, visible and near-infrared images of late type galaxies., 17 pages, 13 figures (higher resolution images available on request). Accepted in A&A (in press)

We reassess the applicability of the Toomre criterion in galactic disks and we study the local star formation law in 16 disk galaxies for which abundance gradients are published. The data we use consists of stellar light profiles, atomic and molecular gas (deduced from CO with a metallicity-dependent conversion factor), star formation rates (from H-alpha emissivities), metallicities, dispersion velocities and rotation curves. We show that the Toomre criterion applies successfully to the case of the Milky Way disk, but it has limited success with the data of our sample; depending on whether the stellar component is included or not in the stability analysis, we find average values for the threshold ratio of the gas surface density to the critical surface density in the range 0.5 to 0.7. We also test various star formation laws proposed in the literature, i.e. either the simple Schmidt law or modifications of it, that take into account dynamical factors. We find only small differences among them as far as the overall fit to our data is concerned; in particular, we find that all three SF laws (with parameters derived from the fits to our data) match particularly well observations in the Milky Way disk. In all cases we find that the exponent n of our best fit SFR has slightly higher values than in other recent works and we suggest several reasons that may cause that discrepancy., 18 pages, 12 figures, accepted in MNRAS

We show that simple models of the chemical and spectrophotometric evolution of galaxies can be used to explore the properties of present-day galaxies and especially the causes of the observed variety among disc galaxies. We focus on the link between ‘classical’ spirals and Low Surface Brightness galaxies.

We model the chemical and spectrophotometric evolution of the Milky Way, spiral galaxies and Low Surface Brightness Galaxies in a consistent way. Some consequences with respect to the nature of Damped Lyman-α systems (DLAs) are investigated.

We present evidence for kinematically decoupled cores (KDCs) in two dwarf early-type (dE) galaxies in the Virgo cluster, VCC 1183 and VCC 1453, studied as part of the SMAKCED stellar absorption-line spectroscopy and imaging survey. These KDCs have radii of 1.8'' (0.14 kpc) and 4.2'' (0.33 kpc), respectively. Each of these KDCs is distinct from the main body of its host galaxy in two ways: (1) inverted sense of rotation; and (2) younger (and possibly more metal-rich) stellar population. The observed stellar population differences are probably associated with the KDC, although we cannot rule out the possibility of intrinsic radial gradients in the host galaxy. We describe a statistical analysis method to detect, quantify the significance of, and characterize KDCs in long-slit rotation curve data. We apply this method to the two dE galaxies presented in this paper and to five other dEs for which KDCs have been reported in the literature. Among these seven dEs, there are four significant KDC detections, two marginal KDC detections, and one dE with an unusual central kinematic anomaly that may be an asymmetric KDC.The frequency of occurence of KDCs and their properties provide important constraints on the formation history of their host galaxies. We discuss different formation scenarios for these KDCs in cluster environments and find that dwarf-dwarf wet mergers or gas accretion can explain the properties of these KDCs. Both of these mechanisms require that the progenitor had a close companion with a low relative velocity. This suggests that KDCs were formed in galaxy pairs residing in a poor group environment or in isolation whose subsequent infall into the cluster quenched star formation., 14 pages, accepted for publication in ApJ

We explore the implications for the high redshift universe of ``state-of-the-art'' models for the chemical and spectrophotometric evolution of spiral galaxies. The models are based on simple ``scaling relations'' for discs, obtained in the framework of Cold Dark Matter models for galaxy formation, and were ``calibrated'' as to reproduce the properties of the Milky Way and of nearby discs (at redshift z~0). In this paper, we compare the predictions of our ``hybrid'' approach to galaxy evolution to observations at moderate and high redshift. We find that the models are in fairly good agreement with observations up to z~1, while some problems appear at higher redshift (provided there is no selection bias in the data); these discrepancies may suggest that galaxy mergers (not considered in this work) played a non negligible role at z>1. We also predict the existence of a ``universal'' correlation between abundance gradients and disc scalelengths, independent of redshift., 14 pages, 11 figures, MNRAS, in press

We study the star formation history of normal spirals by using a large and homogeneous data sample of local galaxies. For our analysis we utilise detailed models of chemical and spectrophotometric galactic evolution, calibrated on the Milky Way disc. We find that star formation efficiency is independent of galactic mass, while massive discs have, on average, lower gas fractions and are redder than their low mass counterparts; put together, these findings convincingly suggest that massive spirals are older than low mass ones. We evaluate the effective ages of the galaxies of our sample and we find that massive spirals must be several Gyr older than low mass ones. We also show that these galaxies (having rotational velocities in the 80-400 km/s range) cannot have suffered extensive mass losses, i.e. they cannot have lost during their lifetime an amount of mass much larger than their current content of gas+stars., Comment: 11 pages, 8 figures, MNRAS in press

The Milky Way is a heterogeneous system, with at least three components (halo, bulge, disk) having very different chemical, photometric and kinematical properties. A reliable model for the evolution of the Milky Way accounting for those properties does not exist at present. In particular, it is not clear how the various components are related, e.g. whether the evolution of the halo has affected in an important way the one of the bulge or the disk (and vice versa); in fact, it seems that the halo evolution has been completely decoupled from the one of the disk, who evolved quite independently (e.g. Gihnore and Wyse 1998). Neither is it clear whether there has been significant interaction between the various parts of the disk, through large scale gas mouvements in the radial direction. Despite the development of various models, all these issues are still open

We study the relations between luminosity and chemical abundance profiles of spiral galaxies, using detailed models for the chemical and spectro-photometric evolution of galactic discs. The models are ``calibrated'' on the Milky Way disc and are successfully extended to other discs with the help of simple ``scaling'' relations, obtained in the framework of semi-analytic models of galaxy formation. We find that our models exhibit oxygen abundance gradients that increase in absolute value with decreasing disc luminosity (when expressed in dex/kpc) and are independent of disc luminosity (when expressed in dex/scalelength), both in agreement with observations. We notice an important strong correlation between abundance gradient and disc scalelength. These results support the idea of ``homologuous evolution'' of galactic discs., 9 pages, 6 postscript figures, MNRAS in press

The chemical and spectro-photometric evolution of spiral galaxies is investigated with detailed models, making use of up-to-date ingredients (like metallicity dependent stellar properties) and a prescription for the star formation rate (SFR) justified both empirically and theoretically. As a first application, the model is used to describe the evolution of the Milky Way. The role of the adopted scheme of disk formation (``inside-out'') in shaping the various chemical and colour profiles is investigated, as well as the role of extinction. It is shown that the solar neighborhood does not evolve as the Milky Way as a whole and that one-zone models with a non-linear SFR prescription cannot be used to study the evolution of our Galaxy. Our model average SFR is shown to match well observations of external spirals., 21 pages, 10 figures, accepted in MNRAS

We study the chemical and spectro-photometric evolution of galactic disks with detailed models calibrated on the Milky Way and using simple scaling relations, based on currently popular semi-analytic models of galaxy formation. We compare our results to a large body of observational data on present day galactic disks, including: disk sizes and central surface brightness, Tully-Fisher relations in various wavelength bands, colour-colour and colour-magnitude relations, gas fractions vs. magnitudes and colours, abundances vs. local and integrated properties, as well as spectra for different galactic rotational velocities. Despite the extremely simple nature of our models, we find satisfactory agreement with all those observables, provided the timescale for star formation in low mass disks is longer than for more massive ones. This assumption is apparently in contradiction with the standard picture of hierarchical cosmology. We find, however, that it is extremely successfull in reproducing major features of present day disks, like the change in the slope of the Tully-Fisher relation with wavelength, the fact that more massive galaxies are on average ``redder'' than low mass ones (a generic problem of standard hierarchical models) and the metallicity-luminosity relation for spirals. It is concluded that, on a purely empirical basis, this new picture at least as successful as the standard one. Observations at high redshifts could help to distinguish between the two possibilities., Comment: 20 pages, 16 figures, MNRAS, accepted for publication