Integral Field Spectroscopy of the cometary starburst galaxy NGC 4861

Financial support from the Spanish Ministerio de Economía y Competitividad under grant PID2019-107408GB-C44, from Junta de Andalucia under project P18-FR-2664, and also from the grant CEX2021-001131-S funded by MCIN/AEI/ 10.13039/501100011033. P P thanks Fundaçao para a Ciencia e a Tecnologia (FCT) for managing research funds graciously provided to Portugal by the EU. This work was supported through FCT grants UID/FIS/04434/2019, UIDB/04434/2020, UIDP/04434/2020 and the project ‘Identifying the Earliest Supermassive Black Holes with ALMA (IdEaS with ALMA) (PTDC/FIS-AST/29245/2017)’ SDP is grateful to the Fonds de Recherche du Québec - Nature et Technologies. SDP also acknowledges financial support from Juan de la Cierva Formación Fellowship (FJC2021-047523-I) financed by MCIN/AEI/10.130395011000110333 and by the European Union "NextGenerationEU"/PRTR. This study is based on observations collected at the Centro As- tronómico Hispano en Andalucía (CAHA) at Calar Alto, Spain, operated jointly by the Instituto de Astrofísica de Andalucía (CSIC) and Junta de Andalucía. The CAHA Archive is part of the Spanish Virtual Observatory project funded by MCIN/AEI/10.13039/501100011033 through grant PID2020-112949GB-I00 CAB (INTA-CSIC). Part based on observations made with the NASA/ESA Hubble Space Telescope, and obtained from the Hubble Legacy Archive, which is a collaboration between the Space Telescope Science Institute (STScI/NASA), the Space Telescope European Coordinating Fa-cility (ST-ECF/ESA) and the Canadian Astronomy Data Centre (CADC/NRC/CSA). This research has made use of the NASA/IPAC Extragalactic Data base (NED), which is funded by the National Aeronautics and Space Administration and operated by the California Institute of Technology.Using the PMAS Integral Field Unit on the Calar Alto 3.5 m telescope, we observed the southern component (Markarian 59) of the ‘cometary’ starburst galaxy NGC 4861. Mrk 59 is centred on a giant nebula and concentration of stars 1 kpc in diameter. Strong H α emission points to a star-formation rate (SFR) at least 0.47 M⊙ yr−1. Mrk 59 has a very high [O III] λ5007/H β ratio, reaching 7.35 in the central nebula, with a second peak at a star-forming hotspot further north. Fast outflows are not detected but nebular motion and galaxy rotation produce relative velocities up to 40 km s−1. Spectral analysis of different regions with ‘Fitting Analysis using Differential evolution Optimization’ (FADO) finds that the stars in the central and ‘spur’ nebulae are very young, ≤ 125 Myr with a large < 10 Myr contribution. Older stars (∼ 1 Gyr) make up the northern disk component, while the other regions show mixtures of 1 Gyr age with very young stars. This and the high specific SFR ∼ 3.5 Gyr−1 imply a bimodal star formation history, with Mrk 59 formed in ongoing starbursts fuelled by a huge gas inflow, turning the galaxy into an asymmetric ‘green pea’ or blue compact dwarf. We map the He II λ4686 emission, and identify a broad component from the central nebula, consistent with the emission of ∼300 Wolf–Rayet stars. About a third of the He II λ4686 flux is a narrow line emitted from a more extended area covering the central and spur nebulae, and may have a different origin.Centro Astronómico Hispano en AndalucíaIPACNational Aeronautics and Space Administration NASAEuropean Commission PTDC/FIS-AST/29245/2017, UID/FIS/04434/2019 ECEuropean Space Agency ESAMinisterio de Economía y Competitividad PID2019-107408GB-C44 MINECOMinisterio de Ciencia e Innovación MICINNJunta de Andalucía CEX2021-001131-S, P18-FR-2664Agencia Estatal de Investigación AEIInstituto de Astrofísica de Andalucía PID2020-112949GB-I00 CAB (INTA-CSIC IA

SIT 45: An interacting, compact, and star-forming isolated galaxy triplet

Acknowledgements. We thank our referee whose valuable comments have certainly contributed to improve and clarify this paper. MAF and PVB acknowledge financial support by the DI-PUCV research project 039.481/2020. MAF also acknowledges support from FONDECYT iniciación project 11200107 and the Emergia program (EMERGIA20_38888) from Consejería de Transformación Económica, Industria, Conocimiento y Universidades and University of Granada. UL and DE acknowledge support from project PID2020-114414GB- 100, financed by MCIN/AEI/10.13039/501100011033. DE also acknowledges support from Beatriz Galindo senior fellowship (BG20/00224) financed by the Spanish Ministry of Science and Innovation, and project PID2020-114414GB- 100 financed by MCIN/AEI/10.13039/501100011033. UL, SV and DE acknowledge support from project P20_00334 financed by the Junta de Andalucía and from FEDER/Junta de Andalucía-Consejería de Transformación Económica, Industria, Conocimiento y Universidades/Proyecto A-FQM-510-UGR20. MB gratefully acknowledges support by the ANID BASAL project FB210003 and from the FONDECYT regular grant 1211000. SDP is grateful to the Fonds de Recherche du Québec – Nature et Technologies and acknowledges financial support from the Spanish Ministerio de Economía y Competitividad under grants AYA2016-79724-C4-4-P and PID2019-107408GB-C44, from Junta de Andalucía Excellence Project P18-FR-2664, and also acknowledges support from the State Agency for Research of the Spanish MCIU through the ‘Center of Excellence Severo Ochoa’ award for the Instituto de Astrofísica de Andalucía (SEV-2017-0709). This research made use of Astropy, a community-developed core Python (http://www.python.org) package for Astronomy (Astropy Collaboration 2013); Ipython (Pérez & Granger 2007); Matplotlib (Hunter 2007); Numpy (Walt et al. 2011); Scipy (Jones et al. 2001); and Topcat (Taylor 2005). This research made use of Astrodendro, a Python package to compute dendrograms of Astronomical data (http:// www.dendrograms.org/). This research has made use of the NASA/IPAC Extragalactic Database, operated by the Jet Propulsion Laboratory of the California Institute of Technology, un centract with the National Aeronautics and Space Administration. Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the U.S. Department of Energy O ce of Science. The SDSS-III Web site is http://www.sdss3.org/. The SDSS-IV site is http://www.sdss. org. Based on observations made with the NASA Galaxy Evolution Explorer (GALEX). GALEX is operated for NASA by the California Institute of Technology under NASA contract NAS5-98034. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory /California Institute of Technology, funded by the National Aeronautics and Space Administration.Context. The underlying scenario of the formation and evolution of galaxy triplets is still uncertain. Mergers of galaxies in isolated triplets give us the opportunity to study the already complex merging process, with minimal contamination of other environmental effects that potentially allow and accelerate galaxy transitions from active star-forming to passive galaxies. Aims. The merging system SIT 45 (UGC 12589) is one of 315 systems in the SDSS-based catalogue of Isolated Triplets (SIT); it is an unusual isolated galaxy triplet, consisting of three merging late-type galaxies. The main aims of this work are to study the dynamical evolution and star formation history (SFH) of SIT 45, as well as its dependence on its local and large-scale environment. Methods. To study its dynamics, parameters such as the velocity dispersion (σv), the harmonic radius (RH), the crossing time (H0tc), and the virial mass (Mvir), along with the compactness of the triplet (S) were considered. To investigate the possible dependence of these dynamical parameters on the environment, the tidal force Q parameters (both local and large-scale) and the projected local density (ηk) were used. To constrain the SFH, we used CIGALE to fit its observed spectral energy distribution using multiwavelength data from the ultraviolet to the infrared. Results. SIT 45 is one of the most compact triplets in the SIT, and it is also more compact than triplets in other samples. According to its SFH, SIT 45 presents star formation, where the galaxies also present recent (∼200 Myr) star formation increase, indicating that this activity may have been triggered by the interaction. Its dynamical configuration suggests that the system is highly evolved in comparison to the SIT. However, this is not expected for systems composed of star-forming late-type galaxies, based on observations in compact groups. Conclusions. We conclude that SIT 45 is a system of three interacting galaxies that are evolving within the same dark matter halo; its compact configuration is a consequence of the ongoing interaction rather than being due to a long-term evolution (as suggested from its H0tc value). We consider two scenarios for the present configuration of the triplet, one where one of the members is a tidal galaxy, and another where this galaxy arrives to the system after the interaction. Both scenarios need further exploration. The isolated triplet SIT 45 is therefore an ideal system to study short timescale mechanisms (∼108 yr), such as starbursts triggered by interactions which are more frequent at higher redshift.DI-PUCV research project 039.481/2020FONDECYT iniciación project 11200107Emergia program (EMERGIA20_38888) from Consejería de Transformación Económica, Industria, Conocimiento y UniversidadesUniversity of GranadaProject PID2020-114414GB- 100, financed by MCIN/AEI/10.13039/501100011033Senior fellowship (BG20/00224) financed by the Spanish Ministry of Science and InnovationProject PID2020-114414GB- 100 financed by MCIN/AEI/10.13039/501100011033Project P20_00334 financed by the Junta de Andalucía and from FEDER/Junta de Andalucía-Consejería de Transformación Económica, Industria, Conocimiento y Universidades/Proyecto A-FQM-510-UGR20ANID BASAL project FB210003FONDECYT regular grant 1211000Fonds de Recherche du Québec – Nature et TechnologiesSpanish Ministerio de Economía y Competitividad under grants AYA2016-79724-C4-4-P and PID2019-107408GB-C44Junta de Andalucía Excellence Project P18-FR-2664State Agency for Research of the Spanish MCIU through the ‘Center of Excellence Severo Ochoa’ award for the Instituto de Astrofísica de Andalucía (SEV-2017-0709

The dependence of oxygen and nitrogen abundances on stellar mass from the CALIFA survey

Context. The study of the integrated properties of star-forming galaxies is central to understand their formation and evolution. Some of these properties are extensive and therefore their analysis require totally covering and spatially resolved observations. Among these properties, metallicity can be defined in spiral discs by means of integral field spectroscopy (IFS) of individual H ii regions. The simultaneous analysis of the abundances of primary elements, as oxygen, and secondary, as nitrogen, also provides clues about the star formation history and the processes that shape the build-up of spiral discs. Aims. Our main aim is to analyse simultaneously O/H and N/O abundance ratios in H ii regions in different radial positions of the discs in a large sample of spiral galaxies to obtain the slopes and the characteristic abundance ratios that can be related to their integrated properties. Methods. We analysed the optical spectra of individual selected H ii regions extracted from a sample of 350 spiral galaxies of the CALIFA survey. We calculated total O/H abundances and, for the first time, N/O ratios using the semi-empirical routine Hii-Chi-mistry, which, according to Pérez-Montero (2014, MNRAS, 441, 2663), is consistent with the direct method and reduces the uncertainty in the O/H derivation using [N ii] lines owing to the dispersion in the O/H-N/O relation. Then we performed linear fittings to the abundances as a function of the de-projected galactocentric distances. Results. The analysis of the radial distribution both for O/H and N/O in the non-interacting galaxies reveals that both average slopes are negative, but a non-negligible fraction of objects have a flat or even a positive gradient (at least 10% for O/H and 4% for N/O). The slopes normalised to the effective radius appear to have a slight dependence on the total stellar mass and the morphological type, as late low-mass objects tend to have flatter slopes. No clear relation is found, however, to explain the presence of inverted gradients in this sample, and there is no dependence between the average slopes and the presence of a bar. The relation between the resulting O/H and N/O linear fittings at the effective radius is much tighter (correlation coefficient ρ = 0.80) than between O/H and N/O slopes (ρ = 0.39) or for O/H and N/O in the individual H ii regions (ρ = 0.37). These O/H and N/O values at the effective radius also correlate very tightly (less than 0.03 dex of dispersion) with total luminosity and stellar mass. The relation with other integrated properties, such as star formation rate, colour, or morphology, can be understood only in light of the found relation with mass.E.P.M., J.M.V., C.K., S.P., and J.I.P. acknowledge support from the Spanish MICINN through grants AYA2010-21887-C04-01 and AYA2013-47742-C4-1-P and the Junta de Andalucia for grant EXC/2011 FQM-7058. R.G.B., R.G.D., and E.P. acknowledge support from grants AYA2014-57490-P and JA-FQM-2828. Support for L.G. is provided by the Ministry of Economy, Development, and Tourism's Millennium Science Initiative through grant IC120009, awarded to The Millennium Institute of Astrophysics, MAS. L.G. acknowledges support by CONICYT through FONDECYT grant 3140566Peer Reviewe

The miniJPAS survey: A search for extreme emission-line galaxies

This is an Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Context. Galaxies with extreme emission lines (EELGs) may play a key role in the evolution of the Universe, as well as in our understanding of the star formation process itself. For this reason an accurate determination of their spatial density and fundamental properties in different epochs of the Universe will constitute a unique perspective towards a comprehensive picture of the interplay between star formation and mass assembly in galaxies. In addition to this, EELGs are also interesting in order to explain the reionization of the Universe, since their interstellar medium (ISM) could be leaking ionizing photons, and thus they could be low z, analogous of extreme galaxies at high z. Aims. This paper presents a method to obtain a census of EELGs over a large area of the sky by detecting galaxies with rest-frame equivalent widths ≥300 Å in the emission lines [O II]λλ3727,3729Å, [O III]λ5007Å, and Hα. For this, we aim to use the J-PAS survey, which will image an area of ≈8000 deg2 with 56 narrow band filters in the optical. As a pilot study, we present a methodology designed to select EELGs on the miniJPAS images, which use the same filter dataset as J-PAS, and thus will be exportable to this larger survey. Methods. We make use of the miniJPAS survey data, conceived as a proof of concept of J-PAS, and covering an area of ≈1 deg2. Objects were detected in the rSDSS images and selected by imposing a condition on the flux in a given narrow-band J-PAS filter with respect to the contiguous ones, which is analogous to requiring an observed equivalent width larger than 300 Å in a certain emission line within the filter bandwidth. The selected sources were then classified as galaxies or quasi-stellar objects (QSOs) after a comparison of their miniJPAS fluxes with those of a spectral database of objects known to present strong emission lines. This comparison also provided a redshift for each source, which turned out to be consistent with the spectroscopic redshifts when available (|Δz/(1 + zspec)| ≤ 0.01). Results. The selected candidates were found to show a compact appearance in the optical images, some of them even being classified as point-like sources according to their stellarity index. After discarding sources classified as QSOs, a total of 17 sources turned out to exhibit EW0 ≥ 300 Å in at least one emission line, thus constituting our final list of EELGs. Our counts are fairly consistent with those of other samples of EELGs in the literature, although there are some differences, which were expected due to biases resulting from different selection criteria. © J. Iglesias-Páramo et al. 2022.This work has been partially funded by projects PID2019-107408GB-C44 from the Spanish PNAYA, co-funded with FEDER, and grand P18-FR-2664, funded by Junta de Andalucía. We acknowledge financial support from the State Agency for Research of the Spanish MCIU through the “Center of Excellence Severo Ochoa” award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709). RGD and LADG acknowledge financial support from the State Agency for Research of the Spanish MCIU through the “Center of Excellence Severo Ochoa” award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709), and PID2019-109067-GB100. IM acknowledges financial support from the State Agency for Research of the Spanish MCIU through the PID2019-106027GB-C41. JCM acknowledges partial support from the Spanish Ministry of Science, Innovation and Universities (MCIU/AEI/FEDER, UE) through the grant PGC2018-097585-B-C22. SDP is grateful to the Fonds de Recherche du Québec – Nature et Technologies. LSJ acknowledges the support of CNPq (304819/2017-4) and FAPESP (2019/10923-5). JAFO acknowledges the financial support from the Spanish Ministry of Science and Innovation and the European Union – NextGenerationEU through the Recovery and Resilience Facility project ICTS-MRR-2021-03- CEFCA. Funding for the J-PAS Project has been provided by the Governments of España and Aragón though the Fondo de Inversión de Teruel, European FEDER funding and the MINECO and by the Brazilian agencies FINEP, FAPESP, FAPERJ and by the National Observatory of Brazil. Based on observations made with the JST/T250 telescope and PathFinder camera for the miniJPAS project at the Observatorio Astrofísico de Javalambre (OAJ), in Teruel, owned, managed, and operated by the Centro de Estudios de Física del Cosmos de Aragón (CEFCA). We acknowledge the OAJ Data Processing and Archiving Unit (UPAD) for reducing and calibrating the OAJ data used in this work. Funding for OAJ, UPAD, and CEFCA has been provided by the Governments of Spain and Aragón through the Fondo de Inversiones de Teruel; the Aragón Government through the Research Groups E96, E103, and E16_17R; the Spanish Ministry of Science, Innovation and Universities (MCIU/AEI/FEDER, UE) with grant PGC2018-097585-B-C21; the Spanish Ministry of Economy and Competitiveness (MINECO/FEDER, UE) under AYA2015-66211-C2-1-P, AYA2015-66211-C2-2, AYA2012-30789, and ICTS-2009-14; and European FEDER funding (FCDD10-4E-867, FCDD13-4E-2685). This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. Funding for SDSS-IV has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the U.S. Department of Energy Office of Science. The SDSS-IV web site is https://www.sdss.org/. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 898633.Peer reviewe

Physical and chemical properties of galaxies with star formation in different environments

This thesis focusses on the study of the properties of galaxies with massive star formation from the perspective of their environments and the possible associated e ects; for this, we study on the one hand general relations of properties like Star Formation Rate (SFR), stellar mass, and metallicity for a large sample of galaxies containing mostly field galaxies (from Sloan Digital Sky Survey, SDSS) and on the other hand, the properties of star formation regions in the compact group of galaxies Stephan’s Quintet (SQ), as inferred from their emission line fluxes. The main objectives of this thesis are: to state the main basic relations of galaxies with star formation in the local Universe. For this, we have selected a large sample (209 276) galaxies from SDSS, and we have studied their main properties relations (SFR, metallicity, stellar mass) taking into account appropriate aperture corrections due to the limited size of the fiber. We have make use of empirical aperture corrections obtained from two-dimensional spectroscopy from the CALIFA project sample of galaxies (Iglesias-P´aramo et al. 2013, 2016), to determine the total value of the emission line fluxes (e.g. [OII] 3727, H , [OIII] 5007, H , and [NII] 6584) of the starforming galaxies from SDSS. to make a complete study of the star formation regions detected in the field of view of SQ by means of the wide field IFTS (imaging Fourier transform spectrometer) SITELLE. Given that galaxy-galaxy interactions are ubiquitous in this group of galaxies, the spatial distribution of the star formation regions is not closely associated with the galaxy discs as in the case of normal spiral galaxies; a non negligible fraction of them are found along tidal tails or other structures resulting from interactions. The combination of the wide field of view of SITELLE and the ability to detect regions with emission lines makes this project unique for a complete study of the main properties of star formation regions in this highly disrupted system of galaxies.Esta tesis se centra en el estudio de las propiedades de las galaxias con formación estelar masiva desde el punto de vista de sus entornos y los posibles efectos asociados; para ello hemos estudiado por un lado las relaciones generales de algunas propiedades como la tasa de formación estelar (SFR), la masa estelar y la metalicidad para una gran muestra representativa de galaxias que contienen principalmente galaxias de campo (de Sloan Digital Sky Survey, SDSS) y, por otro lado, las propiedades de las regiones con formación estelar en el grupo compacto de galaxias conocido como el Quinteto de Stephan (SQ). Los objetivos principales de la tesis son: establecer las principales relaciones básicas de las galaxias con formación estelar en el Universo local. Para ello, hemos seleccionado una gran muestra de galaxias con formación estelar (209 276) de SDSS y hemos estudiado las principales relaciones de sus propiedades (SFR, metalicidad, masa estelar) teniendo en cuenta las correcciones de apertura apropiadas debido al tamaño limitado de las fibras de SDSS. Hemos utilizado correcciones de apertura empíricas obtenidas a partir de la espectroscopia bidimensional de la muestra de galaxias del proyecto CALIFA (Iglesias-Paramo et al. 2013, 2016) para determinar el valor total de los flujos de las líneas de emisión (e.g. [OII] 3727, H , [OIII] 5007, H y [NII] 6584) de las galaxias con formación estelar de SDSS. hacer un estudio completo de las regiones con formación estelar detectadas en el campo de visión de SQ mediante el espectrógrafo de amplio campo de transformada de Fourier SITELLE. Dado que las interacciones galaxia-galaxia predominan en este grupo compacto de galaxias, la distribución espacial de las regiones con formación estelar no están estrechamente asociadas con los discos de las galaxias como en el caso de las galaxias espirales normales; una fracción no despreciable de ellas se encuentra a lo largo de las colas de marea así como de otras estructuras resultantes de las distintas interacciones. La combinación del amplio campo de visión que tiene SITELLE y la capacidad para detectar regiones con líneas de emisión hace que este proyecto sea único para realizar un estudio completo de las principales propiedades de las regiones con formación estelar en este sistema de galaxias altamente perturbado.Tesis Univ. Granada

CO-CAVITY pilot survey: Molecular gas and star formation in void galaxies

Acknowledgements. We appreciate the detailed and useful comments of the referee which helped to improve the clarity of the paper. We acknowledge support (proyect AYA2017-84897-P) from the Spanish Ministerio de Economía y Competitividad, from the European Regional Development Funds (FEDER) and the Junta de Andalucía (Spain) grants FQM108. This work is based on observations carried out under project numbers 075-19 with the IRAM 30-m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). J. F.-B. acknowledges support through the RAVET project by the grant PID2019-107427GB-C32 from the Spanish Ministry of Science, Innovation and Universities (MCIU), and through the IAC project TRACES which is partially supported through the state budget and the regional budget of the Consejería de Economía, Industria, Comercio y Conocimiento of the Canary Islands Autonomous Community. S.D.P. is grateful to the Fonds de Recherche du Québec – Nature et Technologies and acknowledge financial support from the Spanish Ministerio de Economía y Competitividad under grants AYA2016-79724-C4-4-P and PID2019-107408GB-C44, from Junta de Andalucía Excellence Project P18-FR-2664, and also acknowledges support from the State Agency for Research of the Spanish MCIU through the ‘Center of Excellence Severo Ochoa’ award for the Instituto de Astrofísica de Andalucía (SEV-2017-0709). This research made use of Astropy, a community-developed core Python (http://www.python.org) package for Astronomy (Astropy Collaboration 2013, 2018); ipython (Pérez & Granger 2007); mat-plotlib (Hunter 2007); SciPy, a collection of open source software for scientific computing in Python (Virtanen et al. 2020); APLpy, an open-source plotting package for Python (Robitaille & Bressert 2012; Robitaille 2019); and NumPy, a structure for efficient numerical computation (van der Walt et al. 2011).Context. Voids are the most under-dense large-scale regions in the Universe. Galaxies inhabiting voids are one of the keys for understanding the intrinsic processes of galaxy evolution, as external factors such as multiple galaxy mergers or a dense self-collapsing environment are negligible. Aims. We present the first molecular gas mass survey of void galaxies. We compare these new data together with data for the atomic gas mass (MH I) and star formation rate (SFR) from the literature to those of galaxies in filaments and walls in order to better understand how molecular gas and star formation are related to the large-scale environment. Methods. We observed at the IRAM 30 m telescope the CO(1-0) and CO(2-1) emission of 20 void galaxies selected from the Void Galaxy Survey, with a stellar mass range from 108.5 to 1010.3 M·. We detected 15 objects in at least one CO line. We compared the molecular gas mass (MH2), the star formation efficiency (SFE = SFR/MH2), the atomic gas mass, the molecular-to-atomic gas mass ratio, and the specific star formation rate (sSFR) of the void galaxies with two control samples of galaxies in filaments and walls, selected from xCOLD GASS and EDGE-CALIFA, for different stellar mass bins and taking the star formation activity into account. Results. In general, we do not find any significant differences between void galaxies and the control sample. In particular, we do not find any evidence for a difference in the molecular gas mass or molecular gas mass fraction. For the other parameters (SFE, atomic gas mass, molecular-to-atomic gas mass ratio, and sSFR), we also find similar (within the errors) mean values between void and filament and wall galaxies when the sample is limited to star-forming galaxies. We find no evidence for an enhanced sSFR in void galaxies. Some tentative differences emerge when trends with stellar mass are studied: The SFE of void galaxies might be lower than in filament and wall galaxies for low stellar masses, and there might be a trend of increasing deficiency in the HI content in void galaxies compared to galaxies in filaments and walls for higher stellar masses, accompanied by an increase in the molecular-to-atomic gas mass ratio. However, all trends with stellar mass are based on a low number of galaxies and need to be confirmed for a larger sample. Conclusions. The results for the molecular gas mass for a sample of 20 voids galaxies allowed us to make a statistical comparison to galaxies in filaments and walls for the first time. We do not find any significant differences of the molecular gas properties and the SFE, but we note that a larger sample is necessary to confirm this and be sensitive to subtle trends.Consejería de Economía, Industria, Comercio y ConocimientoINSUInstituto de Astrofísica de Andalucía SEV-2017-0709Junta de Andalucía Excellence Project P18-FR-2664State Agency for ResearchMinisterio de Ciencia, Innovación y UniversidadesFonds de recherche du Québec – Nature et technologies AYA2016-79724-C4-4-P, PID2019-107408GB-C44Ministerio de Economía y CompetitividadCentre National de la Recherche Scientifique PID2019-107427GB-C32European Regional Development FundJunta de Andalucía FQM10

Searching for intergalactic star forming regions in Stephan's Quintet with SITELLE I. Ionised gas structures and kinematics

Stephan's Quintet (SQ), the prototypical compact group of galaxies in the local Universe, has been observed with the imaging Fourier transform spectrometer SITELLE, attached to the Canada-France-Hawaii-Telescope, to perform a deep search for intergalactic star-forming emission. In this paper we present the extended ionised gaseous structures detected and analyse their kinematical properties. The large field of view (11' x 11') and the spectral ranges of SITELLE have allowed a thorough study of the entire galaxy system, its interaction history and the main properties of the ionised gas. The observations have revealed complex three-dimensional strands in SQ seen for the first time, as well as the spatially resolved velocity field for a new SQ dwarf galaxy (M 82-like) and the detailed spectral map of NGC7320c, confirming its AGN nature. A total of 175 SQ H alpha emission regions have been found, 22 of which present line profiles with at least two kinematical components. We studied 12 zones and 28 sub-zones in the SQ system in order to define plausible physical spatial connections between its different parts in the light of the kinematical information gathered. In this respect we have found five velocity systems in SQ: (i) v = [5600-5900] km s(-1) associated with the new intruder and the southern debris region; (ii) v = [5900-6100] km s(-1), associated with the north starburst A and south starburst A and the strands connected to these zones; (iii) v = [6100-6600] km s(-1), associated with the strands from the large-scale shock region (LSSR); (iv) v = [6600-6800] km s(-1), associated with the young tidal tail, the starburst A (SQA), NGC7319, and the NGC7319 north lobe; and (v) v = [6800-7000] km s(-1), associated with the strands seen connecting LSSR with SQA. We fail to detect ionised gas emission in the old tail, neither in the vicinity of NGC7318A nor in NGC7317, and the connection between NGC7319 north lobe and SQA cannot be confirmed. Conversely, a clear gaseous bridge has been confirmed both spatially and kinematically between the LSSR zone and the NGC7319 AGN nucleus. Finally, a larger scale, outer rim winding the NGC7318B/A system clockwise north-west to south-east has been highlighted in continuum and in H alpha. This structure may be reminiscent of a sequence of a previously proposed scenario for SQ a sequence of individual interactions.© ESO 2019.SDP, JIP, JVM, and CK acknowledge financial support from the Spanish Ministerio de Economia y Competitividad under grants AYA2013-47742-C4-1-P and AYA2016-79724C4-4-P, from Junta de Andalucia Excellence Project PEX2011-FQM-7058, and also acknowledge support from the State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award for the Instituto de Astrofisica de Andalucia (SEV-2017-0709). LD is grateful to the Natural Sciences and Engineering Research Council of Canada, the Fonds de Recherche du Quebec, and the Canada Foundation for Innovation for funding.Peer reviewe

Understanding the role of morphology and environment in the dynamical evolution of isolated galaxy triplets

Context. The environments where galaxies reside affects their evolutionary histories. Galaxy triplets (systems composed of three physically bound galaxies) are one of simplest groups of galaxies, and are therefore excellent laboratories to study evolutionary mechanisms where effects of the environment are minimal. Aims. We present a statistical study of the dynamical properties of isolated galaxy triplets as a function of their local and large-scale environments. To explore the connection of the dynamical evolution on the systems with the evolution of the galaxies composing the triplets, we consider observational properties such as morphology and star formation rate (SFR). Methods. We used the SDSS-based catalogue of Isolated Triplets (SIT), which contains 315 triplets. We classified each triplet ac cording to galaxy morphologies and defined a parameter Qtrip to quantify the total local tidal strengths in the systems. To quantify the dynamical stage of the system we used the parameters of harmonic radius RH, velocity dispersion σvr , crossing time H0tc , and virial mass Mvir. Results. Triplets composed of three early-type galaxies present the smallest RH, indicating that they are in general more compact than triplets with one or more late-type galaxies. Among triplets with low values of RH and H0tc , SIT triplets with Qtrip < −2 are relaxed systems that are more dynamically evolved, while triplets with Qtrip > −2 show compact configurations due to interactions within the system, such as ongoing mergers. Conclusions. We found that there is no dominant galaxy in triplets in terms of properties of stellar populations such as global colour and SFR. Moreover, the global SFR in isolated triplets composed of two or more early-type galaxies increases with the stellar mass ratio of the galaxies with respect to the central galaxy, therefore the system is globally ‘rejuvenated’DI-PUCV research project 039.481/2020Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) CONICYT FONDECYT 11200107Consejeria de Transformacion Economica, Industria, Conocimiento y Universidades EMERGIA20_38888University of GranadaJunta de Andalucia P20_00334FEDER/Junta de Andalucia-Consejeria de Transformacion Economica, Industria, Conocimiento y Universidades A-FQM-510-UGR20Spanish Government AYA2016-79724-C4-4-P PID2019-107408GB-C44Junta de Andalucia P18-FR-2664Spanish Government SEV-2017-0709Alfred P. Sloan FoundationNational Science Foundation (NSF)United States Department of Energy (DOE)National Aeronautics & Space Administration (NASA) NAS5-9803

Photon leaking or very hard ionizing radiation? Unveiling the nature of Hea II -emitters using the softness diagram

Aims. Star-forming galaxies with nebular Hea II emission contain very energetic ionizing sources of radiation, which can be considered as analogs to the major contributors of the reionization of the Universe in early epochs. It is therefore of great importance to provide a reliable absolute scale for the equivalent effective temperature (T∗) for these sources. Methods. We study a sample of local (za < a 0.2) star-forming galaxies showing optical nebular Hea II emission using the so-called softness diagrams, involving emission lines of two elements in two consecutive stages of ionization (e.g., [Sa II]/[Sa III] vs. [Oa II]/[Oa III]). We use for the first time the Hea I/Hea II ratio in these diagrams in order to explore the higher range of T∗ expected in these objects, and to investigate the role of possible mechanisms driving the distribution of galaxy points in these diagrams. We build grids of photoionization models covering different black-body temperatures, model cluster atmospheres, and density-bounded geometries to explain the conditions observed in the sample. Results. We verified that the use of the softness diagrams including the emission-line ratio Hea I/Hea II combined with black-body photoionization models can provide an absolute scale of T∗ for these objects. The application of a Bayesian-like code indicates T∗ in the range 50-80 kK for the sample of galaxies, with a mean value higher than 60 kK. The average of these high temperature values can only be reproduced using cluster model populations with nearly metal-free stars, although such ionizing sources cannot explain either the highest T∗ values, beyond 1σ, or the dispersion observed in the softness diagrams. According to our photoionization models, most sample galaxies could be affected to some extent by ionizing photon leaking, presenting a mean photon absorption fraction of 26% or higher depending on the metallicity assumed for the ionizing cluster. The entire range of Hea I/Hea II, [Sa II]/[Sa III], and [Oa II]/[Oa III] ratios for these HeII-emitting galaxies is reproduced with our models, combining nearly metal-free ionizing clusters and photon leaking under different density-bounded conditions. © ESO 2020.We acknowledge financial support from the State Agency for Research of the Spanish MCIU through the “Center of Excellence Severo Ochoa” award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709). This work has been partly funded by projects “Estallidos6” AYA2016-79724-C4(Spanish Ministerio de Economia y Competitividad), “Estallidos7” PID2019-107408GB-C44 (Spanish Ministerio de Ciencia e Innovacion), and from the Junta de Andalucia Excellence project EXC/2011 FQM-7058. RGB acknowledges financial support from the Spanish Ministerio de Economía y Competitividad, through projects AYA2016-77846-P and AYA2014- 57490-P. EPM also acknowledges the assistance from his guide dog Rocko without whose daily help this work would have been much more difficult.Peer reviewe

SIT 45: An interacting, compact, and star-forming isolated galaxy triplet

Context. The underlying scenario of the formation and evolution of galaxy triplets is still uncertain. Mergers of galaxies in isolated triplets give us the opportunity to study the already complex merging process, with minimal contamination of other environmental effects that potentially allow and accelerate galaxy transitions from active star-forming to passive galaxies.Aims. The merging system SIT 45 (UGC 12589) is one of 315 systems in the SDSS-based catalogue of Isolated Triplets (SIT); it is an unusual isolated galaxy triplet, consisting of three merging late-type galaxies. The main aims of this work are to study the dynamical evolution and star formation history (SFH) of SIT 45, as well as its dependence on its local and large-scale environment.Methods. To study its dynamics, parameters such as the velocity dispersion (sigma(v)), the harmonic radius (R-H), the crossing time (H(0)t(c)), and the virial mass (M-vir), along with the compactness of the triplet (S) were considered. To investigate the possible dependence of these dynamical parameters on the environment, the tidal force Q parameters (both local and large-scale) and the projected local density (eta(k)) were used. To constrain the SFH, we used CIGALE to fit its observed spectral energy distribution using multiwavelength data from the ultraviolet to the infrared.Results. SIT 45 is one of the most compact triplets in the SIT, and it is also more compact than triplets in other samples. According to its SFH, SIT 45 presents star formation, where the galaxies also present recent (similar to 200 Myr) star formation increase, indicating that this activity may have been triggered by the interaction. Its dynamical configuration suggests that the system is highly evolved in comparison to the SIT. However, this is not expected for systems composed of star-forming late-type galaxies, based on observations in compact groups.Conclusions. We conclude that SIT 45 is a system of three interacting galaxies that are evolving within the same dark matter halo; its compact configuration is a consequence of the ongoing interaction rather than being due to a long-term evolution (as suggested from its H(0)t(c) value). We consider two scenarios for the present configuration of the triplet, one where one of the members is a tidal galaxy, and another where this galaxy arrives to the system after the interaction. Both scenarios need further exploration. The isolated triplet SIT 45 is therefore an ideal system to study short timescale mechanisms (similar to 10(8) yr), such as starbursts triggered by interactions which are more frequent at higher redshift.DI-PUCV research project 039.481/2020Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) CONICYT FONDECYT 1211000Consejeria de Transformacion Economica, Industria, Conocimiento y Universidades EMERGIA20_38888University of GranadaMCIN/AEI PID2020-114414GB-100Ministry of Science and Innovation, Spain (MICINN) BG20/00224Junta de Andalucia P20_00334 FEDER/Junta de Andalucia-Consejeria de Transformacion Economica, Industria, Conocimiento y Universidades A-FQM-510-UGR20ANID BASAL project FB210003Spanish Government AYA2016-79724-C4-4-P PID2019-107408GB-C44Junta de Andalucia P18-FR-2664State Agency for Research of the Spanish MCIU through the Center of Excellence Severo Ochoa' award for the Instituto de Astrofisica de Andalucia SEV-2017-0709Alfred P. Sloan FoundationNational Science Foundation (NSF)United States Department of Energy (DOE)National Aeronautics & Space Administration (NASA