Suchergebnisse

Off-centered spots of the enhanced gas velocity dispersion, σ, are revealed in some galaxies from the Mapping Nearby Galaxies at Apache Point Observatory survey (MaNGA). Aiming to clarify the origin of the spots of enhanced σ, we examine the distributions of the surface brightness, the line-of-sight velocity, the oxygen abundance, the gas velocity dispersion, and the Baldwin-Phillips-Terlevich spaxel classification in seven galaxies. We find that the enhanced σ spots in six galaxies can be attributed to a (minor) interaction with a satellite. Three galaxies in our sample have a very close satellite (the separation in the sky plane is comparable to the optical radius of the galaxy). The spots of enhanced σ in those galaxies are located at the edge of the galaxy close to the satellite. The spots of enhanced σ in three other galaxies are related to bright spots in the photometric B band within the galaxy, which can be due to the projection of a satellite in the line of sight of the galaxy. The oxygen abundances in the spots in these three galaxies are reduced. This suggests that the low-metallicity gas from the satellite is mixed with the interstellar medium of the disk, that is, the gas exchange between the galaxy and its satellite takes place. The spectra of the spaxels within a spot are usually H※ II-region-like, suggesting that the interaction (gas infall) in those galaxies does not result in appreciable shocks. In contrast, the spot of the enhanced σ in the galaxy M-8716-12703 is associated with an off-centered active galactic nucleus-like radiation distribution. One can suggest that the spot of the enhanced σ in the M-8716-12703 galaxy is different in origin, or that the characteristics of gas infall in this case differs from that in other galaxies. © ESO 2021. ; L.S.P acknowledges support within the framework of the program of the NAS of Ukraine Support for the development of priority fields of scientific research (CPCEL 6541230)". BC, JN and MG are supported by AYA2014-58861-C3-1-P. I.A.Z acknowledges support by the National Academy of Sciences of Ukraine under the Research Laboratory Grant for young scientists No. 0120U100148. AMP is supported by AYA2017-88007-C3-2, MDM2017-0737 (Unidad de Excelencia Maria de Maeztu, CAB). JMV and SDP acknowledge financial support from the Spanish Ministerio de Economia y Competitividad under grants AYA2016-79724-C4-4-P and PID2019-107408GBC44, from Junta de Andalucia Excellence Project P18-FR-2664, 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). SDP is grateful to the Fonds de Recherche du Quebec - Nature et Technologies. The work is performed according to the Russian Government Program of Competitive Growth of Kazan Federal University and Russian Science Foundation, grant no. 20-12-00105. This research has made use of the NASA/IPAC Extragalactic Database, which is funded by the National Aeronautics and Space Administration and operated by the California Institute of Technology. We acknowledge the usage of the HyperLeda database (http://leda.univ-lyon1.fr).Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the U.S. Department of Energy O ffice of Science, and the Participating Institutions. SDSS-IV acknowledges support and resources from the Center for High-Performance Computing at the University of Utah. ; Peer reviewed

Context. A sample of low-mass Hα emission line sources at z ∼ 0.4 was studied in the context of the mass-metallicty relation (MZR) and its possible evolution. We drew our sample from the OSIRIS Tunable Emission Line Object (OTELO) survey, which exploits the red tunable filter of OSIRIS at the Gran Telescopio Canarias to perform a blind narrow-band spectral scan in a selected field of the Extended Groth Strip. We were able to directly measure emission line fluxes and equivalent widths from the analysis of OTELO pseudo-spectra. Aims. This study aims to explore the MZR in the very low-mass regime. Our sample reaches stellar masses (M) as low as 10 M, where 63% of the sample have M < 10 M. We also explore the relation of the star formation rate (SFR) and specific SFR with M and gas-phase oxygen abundances, as well as the M-size relation and the morphological classification. Methods. The M were estimated using synthetic rest-frame colours. Using an χ minimization method, we separated the contribution of [N» II]λ6583 to the Hα emission lines. Using the N2 index, we separated active galactic nuclei from star-forming galaxies (SFGs) and estimated the gas metallicity. We studied the morphology of the sampled galaxies qualitatively (visually) and quantitatively (automatically) using high-resolution data from the Hubble Space Telescope-ACS. The physical size of the galaxies was derived from the morphological analysis using GALAPAGOS2/GALFIT, where we fit a single-Sérsic 2D model to each source. Results. We find no evidence for an MZR evolution from comparing our very low-mass sample with local SFGs from the Sloan Digital Sky Survey. Furthermore, the same is true for M-size and M-SFR relations, as we deduce from comparison with recent literature. Morphologically, our sample is mostly (63%) populated by late-Type galaxies, with 13% of early-Type sources. For the first time, we identify one possible candidate outlier in the MZR at z = 0.4. The stellar-mass, metallicity, colour, morphology, and SFR of this source suggest that it is compatible with a transitional dwarf galaxy. ; With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737)

Aims. In this paper, we aim to study the main properties and luminosity function (LF) of the [O II]3727 emitters detected in the OTELO survey in order to characterise the star formation processes in low-mass galaxies at z ∼ 1.43 and to constrain the faint-end of the LF. Methods. Here, we describe the selection method and analysis of the emitters obtained from narrow-band scanning techniques. In addition, we present several relevant properties of the emitters and discuss the selection biases and uncertainties in the determination of the LF and the star formation rate density (SFRD). Results. We confirmed a total of 60 sources from a preliminary list of 332 candidates as [O II]3727 emitters. Approximately 93% of the emitters have masses in the range of 108 < M*/M⊙ < 109. All of our emitters are classified as late-type galaxies, with a lower value of (u − v) when compared with the rest of the emitters of the OTELO survey. We find that the cosmic variance strongly affects the normalisation (ϕ*) of the LF and explains the discrepancy of our results when compared with those obtained from surveys of much larger volumes. However, we are able to determine the faint-end slope of the LF, namely, α = −1.42 ± 0.06, by sampling the LF down to ∼1 dex lower than in previous works. We present our calculation of the SFRD of our sample and compare it to the value obtained in previous studies from the literature. © ESO 2021. ; JAdD thanks the Instituto de Astrofísica de Canarias (IAC) for its support through the Programa de Excelencia Severo Ochoa and the Gobierno de Canarias for the Programa de Talento Tricontinental grant. This work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO) under the grants AYA2013-46724-P, AYA2014-58861-C3-1-P, AYA2014-58861-C3-2-P, AYA2014-58861-C3-3-P, AYA2016-75808-R, AYA2016-75931-C2-1-P, AYA2016-75931-C2-2-P, and MDM-2017-0737 (Unidad de Excelencia María de Maeztu, CAB). This work was supported by the project Evolution of Galaxies, of reference AYA2017-88007-C3-1-P, within the "Programa estatal de fomento de la investigación científica y técnica de excelencia del Plan Estatal de Inves-tigación Científica y Técnica y de Innovación (2013–2016)" of the "Agencia Estatal de Investigación del Ministerio de Ciencia, Innovación y Universidades", and co-financed by the FEDER "Fondo Europeo de Desarrollo Regional". This article is based on observations made with the Gran Telescopio Canarias (GTC) at Roque de los Muchachos Observatory of the Instituto de Astrofísica de Canarias on the island of La Palma. This study makes use of data from AEGIS, a multi-wavelength sky survey conducted with the Chandra, GALEX, Hubble, Keck, CFHT, MMT, Subaru, Palomar, Spitzer, VLA, and other telescopes, and is supported in part by the NSF, NASA, and the STFC. Based on observations obtained with MegaPrime/MegaCam, a joint project of the CFHT and CEA/IRFU, at the Canada–France–Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Science de l'Univers of the Centre National de la Recherche Sci-entifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at Terapix available at the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS. Based on observations obtained with WIRCam, a joint project of CFHT, Taiwan, Korea, Canada, France, at the Canada–France–Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the Institute National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii. This work is based in part on data products produced at TERAPIX, the WIRDS (WIRcam Deep Survey) consortium, and the Canadian Astronomy Data Centre. This research was supported by a grant from the Agence Nationale de la Recherche ANR-07-BLAN-0228. ; With funding from the Spanish government through the 'Severo Ochoa Centre of Excellence' accreditation (SEV-2017-0709). ; Peer reviewed

Context. Computational techniques are essential for mining large databases produced in modern surveys with value-Added products. Aims. This paper presents a machine learning procedure to carry out a galaxy morphological classification and photometric redshift estimates simultaneously. Currently, only a spectral energy distribution (SED) fitting has been used to obtain these results all at once. Methods. We used the ancillary data gathered in the OTELO catalog and designed a nonsequential neural network that accepts optical and near-infrared photometry as input. The network transfers the results of the morphological classification task to the redshift fitting process to ensure consistency between both procedures. Results. The results successfully recover the morphological classification and the redshifts of the test sample, reducing catastrophic redshift outliers produced by an SED fitting and avoiding possible discrepancies between independent classification and redshift estimates. Our technique may be adapted to include galaxy images to improve the classification. © ESO 2021. ; This work was supported by the project Evolution of Galaxies, of reference AYA2014-58861-C3-1-P and AYA2017-88007-C3-1-P, within the "Programa estatal de fomento de la investigación científica y técnica de excelencia del Plan Estatal de Investigación Científica y Técnica y de Innovación (2013-2016" of the "Agencia Estatal de Investigación del Ministerio de Ciencia, Innovación y Universidades", and co-financed by the FEDER "Fondo Europeo de Desarrollo Regional". JAD is grateful for the support from the UNAM-DGAPA-PASPA 2019 program, the UNAM-CIC, the Canary Islands CIE: Tricontinental Atlantic Campus 2017, and the kind hospitality of the IAC. MP acknowledges financial supports from the Ethiopian Space Science and Technology Institute (ESSTI) under the Ethiopian Ministry of Innovation and Technology (MoIT), and from the Spanish Ministry of Economy and Competitiveness (MINECO) through projects AYA2013-42227-P and AYA2016-76682C3-1-P, and from the Spanish Ministerio de Ciencia e Innovación – Agencia Estatal de Investigación through projects PID2019-106027GB-C41 and AYA2016-76682C3-1-P. APG, MSP and RPM were supported by the PNAYA project: AYA2017–88007–C3–2–P. JG was supported by the PNAYA project AYA2018–RTI-096188-B-i00. MC & APG are also funded by Spanish State Research Agency grant MDM-2017-0737 (Unidad de Excelencia María de Maeztu CAB). JIGS receives support through the Proyecto Puente 52.JU25.64661 (2018) funded by Sodercan S.A. and the Universidad de Cantabria, and PGC2018–099705–B–100 funded by the Ministerio de Ciencia, Innovación y Universidades. EJA acknowledges funding 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 from grant PGC2018-095049-B-C21. Based on observations made with the Gran Telescopio Canarias (GTC), installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, in the island of La Palma. This work is (partly) based on data obtained with the instrument OSIRIS, built by a Consortium led by the Instituto de Astrofísica de Canarias in collaboration with the Instituto de Astronomía of the Universidad Autónoma de México. OSIRIS was funded by GRANTECAN and the National Plan of Astronomy and Astrophysics of the Spanish Government. ; Peer reviewed

Context. With an estimated diameter in the 320–350 km range, (704) Interamnia is the fifth largest main belt asteroid and one of the few bodies that fills the gap in size between the four largest bodies with D > 400 km (Ceres, Vesta, Pallas and Hygiea) and the numerous smaller bodies with diameter ≤200 km. However, despite its large size, little is known about the shape and spin state of Interamnia and, therefore, about its bulk composition and past collisional evolution. Aims. We aimed to test at what size and mass the shape of a small body departs from a nearly ellipsoidal equilibrium shape (as observed in the case of the four largest asteroids) to an irregular shape as routinely observed in the case of smaller (D ≤ 200 km) bodies. Methods. We observed Interamnia as part of our ESO VLT/SPHERE large program (ID: 199.C-0074) at thirteen different epochs. In addition, several new optical lightcurves were recorded. These data, along with stellar occultation data from the literature, were fed to the All-Data Asteroid Modeling algorithm to reconstruct the 3D-shape model of Interamnia and to determine its spin state. Results. Interamnia's volume-equivalent diameter of 332 ± 6 km implies a bulk density of ρ = 1.98 ± 0.68 g cm−3, which suggests that Interamnia – like Ceres and Hygiea – contains a high fraction of water ice, consistent with the paucity of apparent craters. Our observations reveal a shape that can be well approximated by an ellipsoid, and that is compatible with a fluid hydrostatic equilibrium at the 2σ level. Conclusions. The rather regular shape of Interamnia implies that the size and mass limit, under which the shapes of minor bodies with a high amount of water ice in the subsurface become irregular, has to be searched among smaller (D ≤ 300 km) less massive (m ≤ 3 × 1019 kg) bodies. ; This work has been supported by the Czech Science Foundation through grant 18-09470S (J.H., J.D.) and by the Charles University Research program No. UNCE/SCI/023. This research was supported by INTER-EXCELLENCE grant LTAUSA18093 from the Czech Ministry of Education, Youth, and Sports (J.H. and O.P.). The research of O.P. is additionally supported by Horizon 2020 ERC Starting Grant "Cat-In-hAT" (grant agreement #803158) and award PRIMUS/SCI/17 from Charles University. P.V., A.D., and B.C. were Aeronautics and Space Administration under Grant No. 80NSSC18K0849 issued through the Planetary Astronomy Program. This work was supported by the National Science Centre, Poland, through grant no. 2014/13/D/ST9/01818 (A.M.). The research leading to these results has received funding from the European Union's Horizon 2020 Research and Innovation Programme, under Grant Agreement no 687378 (SBNAF). This project has been supported by the GINOP-2.3.2-15-2016-00003 and NKFIH K125015 grants of the Hungarian National Research, Development and Innovation Office (NKFIH) and by the Lendület grant LP2012-31 of the Hungarian Academy of Sciences. TRAPPIST-North is a project funded by the University of Liège, in collaboration with Cadi Ayyad University of Marrakech (Morocco). TRAPPIST-South is a project funded by the Belgian FNRS under grant FRFC 2.5.594.09. F.E.J. is a FNRS Senior Research Associate. ASAS-SN thanks the Las Cumbres Observatory and its staff for its continuing support of the ASAS-SN project. ASAS-SN is supported by the Gordon and Betty Moore Foundation through grant GBMF5490 to the Ohio State University and NSF grant AST-1515927. Development of ASAS-SN has been supported by NSF grant AST-0908816, the Mt. Cuba Astronomical Foundation, the Center for Cosmology and AstroParticle Physics at the Ohio State University, the Chinese Academy of Sciences South America Center for Astronomy (CASSACA), the Villum Foundation, and George Skestos.