35 research outputs found
The Lockman-SpReSO project: description, target selection, observations, and catalogue preparation
© TheAuthors 2023. Artículo firmado por 29 autores. We thank the anonymous referee for their useful report. This work was supported by the Evolution of Galaxies project, of references AYA2017-88007-C3-1-P, AYA2017-88007-C3-2-P, AYA2018-RTI-096188-BI00, PID2019-107408GB-C41, PID2019-106027GB-C41, PID2021-122544NB-C41, and MDM-2017-0737 (Unidad de Excelencia María de Maeztu, CAB), 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 Spanish Ministry of Science and Innovation/State Agency of Research MCIN/AEI/10.13039/501100011033 and by `ERDF A way of making Europe'. This article is based on observations made with the Gran Telescopio Canarias (GTC) at Roque de los Muchachos Observatory on the island of La Palma, with the Willian Herschel Telescope (WHT) at Roque de los Muchachos Observatory on the island of La Palma and on observations at Kitt Peak National Observatory, NSF's National Optical-Infrared Astronomy Research Laboratory (NOIRLab Prop. ID: 2018A-0056; PI: Gonzalez-Serrano, J.I.), which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is funded by the National Aeronautics and Space Administration and operated by the California Institute of Technology. J.N. acknowledges the support of the National Science Centre, Poland through the SONATA BIS grant 2018/30/E/ST9/00208. E.B. and I.C.G. acknowledge support from DGAPA-UNAM grant IN113320. M.P. acknowledges the support from the Space Science and Geospatial Institute under the Ethiopian Ministry of Innovation and Technology (MInT). E.A. and M.P. acknowledge the 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). J.A.D. acknowledges the support of the Universidad de La Laguna through the Proyecto de Internacionalización y Excelencia, Programa Tomás de Iriarte 2022. The authors thank Terry Mahoney (at the IAC's Scientific Editorial Service) for his substantial improvements of the manuscript.Context. Extragalactic surveys are a key tool for better understanding the evolution of galaxies. Both deep and wide-field surveys serve to provide a clearer emerging picture of the physical processes that take place in and around galaxies, and to identify which of these processes are the most important in shaping the properties of galaxies.
Aims. The Lockman Spectroscopic Redshift Survey using Osiris (Lockman-SpReSO) aims to provide one of the most complete optical spectroscopic follow-ups of the far-infrared (FIR) sources detected by the Herschel Space Observatory in the Lockman Hole (LH) field. The optical spectroscopic study of the FIR-selected galaxies supplies valuable information about the relation between fundamental FIR and optical parameters, including extinction, star formation rate, and gas metallicity. In this article, we introduce and provide an in-depth description of the Lockman-SpReSO project and of its early results.
Methods. We selected FIR sources from Herschel observations of the central 24 arcmin x24 arcmin of the LH field with an optical counterpart up to 24.5 R_(C)(AB). The sample comprises 956 Herschel FIR sources, plus 188 additional interesting objects in the field. These are point X-ray sources, cataclysmic variable star candidates, high-velocity halo star candidates, radio sources, very red quasi-stellar objects, and optical counterparts of sub-millimetre galaxies. The faint component of the catalogue (R_(C)(AB) ≥ 20) was observed using the OSIRIS instrument on the 10.4 m Gran Telescopio Canarias in multi-object spectroscopy (MOS) mode. The bright component was observed using two multi-fibre spectrographs: the AF2-WYFFOS at the William Herschel Telescope and the HYDRA instrument at the WYIN telescope.
Results. From an input catalogue of 1144 sources, we measured a secure spectroscopic redshift in the range 0.03 ≲ z ≲ 4.96 for 357 sources with at least two identified spectral lines. In addition, for 99 sources that show only one emission or absorption line, a spectroscopic redshift was postulated based on the line and object properties, and photometric redshift. In both cases, properties of emission and absorption lines were measured. Furthermore, to characterize the sample in more depth with determined spectroscopic redshifts, spectral energy distribution (SED) fits were performed using the CIGALE software. The IR luminosity and the stellar mass estimations for the sample are also presented as a preliminary description.Depto. de Física de la Tierra y AstrofísicaFac. de Ciencias FísicasTRUEhe Spanish Ministry of SciPrograma estatal de fomento de la investigación científica y técnica de excelencia del Plan Estatal de Investigación Científica y Técnica y de Innovación (2013-2016)Unidad de Excelencia María de Maeztu, CABERDF "A way of making Europe"National Science Centre, Poland through the SONATA BISDGAPA-UNAMSpace Science and Geospatial Institute under the Ethiopian Ministry of Innovation and Technology (MInT)Centro de Excellence Severo OchoaUniversidad de La Laguna. Proyecto de Internacionalización y Excelencia, Programa Tomás de Iriarte 2022pu
On the 3D structure of the mass, metallicity, and SFR space for SF galaxies
We demonstrate that the space formed by the star-formation rate (SFR),
gas-phase metallicity (Z), and stellar mass (M), can be reduced to a plane, as
first proposed by Lara-Lopez et al. We study three different approaches to find
the best representation of this 3D space, using a principal component analysis,
a regression fit, and binning of the data. The PCA shows that this 3D space can
be adequately represented in only 2 dimensions, i.e., a plane. We find that the
plane that minimises the chi^2 for all variables, and hence provides the best
representation of the data, corresponds to a regression fit to the stellar mass
as a function of SFR and , M=f(Z,SFR). We find that the distribution
resulting from the median values in bins for our data gives the highest chi^2.
We also show that the empirical calibrations to the oxygen abundance used to
derive the Fundamental Metallicity Relation (Nagao et al.) have important
limitations, which contribute to the apparent inconsistencies. The main problem
is that these empirical calibrations do not consider the ionization degree of
the gas. Furthermore, the use of the N2 index to estimate oxygen abundances
cannot be applied for ~8.8 because of the saturation of the [NII]6584 line in
the high-metallicity regime. Finally we provide an update of the Fundamental
Plane derived by Lara-Lopez et al.Comment: ApJ, accepted. 15 pages, 13 figure
A study of central galaxy rotation with stellar mass and environment
© 2017. The American Astronomical Society. All rights reserved. We present a pilot analysis of the influence of galaxy stellar mass and cluster environment on the probability of slow rotation in 22 central galaxies at mean redshift z = 0.07. This includes new integral-field observations of five central galaxies selected from the Sloan Digital Sky Survey, observed with the SPIRAL integral-field spectrograph on the Anglo-Australian Telescope. The composite sample presented here spans a wide range of stellar masses, 10.9 < log(M∗/M⊙)lt; 12.0, and are embedded in halos ranging from groups to clusters, 12.9 < log(M 200 Ṁ) < 15.6. We find a mean probability of slow rotation in our sample of P(SR) = 54 ± 7%. Our results show an increasing probability of slow rotation in central galaxies with increasing stellar mass. However, when we examine the dependence of slow rotation on host cluster halo mass, we do not see a significant relationship. We also explore the influence of cluster dominance on slow rotation in central galaxies. Clusters with low dominance are associated with dynamically younger systems. We find that cluster dominance has no significant effect on the probability of slow rotation in central galaxies. These results conflict with a paradigm in which halo mass alone predetermines central galaxy properties
The massive relic galaxy NGC 1277 is dark matter deficient. From dynamical models of integral-field stellar kinematics out to five effective radii
According to the CDM cosmology, present-day galaxies with stellar
masses should contain a sizable fraction of
dark matter within their stellar body. Models indicate that in massive
early-type galaxies (ETGs) dark matter should account for of the
dynamical mass within five effective radii (). Most massive ETGs
have been shaped through a two-phase process: the rapid growth of a compact
core was followed by the accretion of an extended envelope through mergers. The
exceedingly rare galaxies that have avoided the second phase, the so-called
relic galaxies, are thought to be the frozen remains of the massive ETG
population at . The best relic galaxy candidate discovered to date
is NGC 1277, in the Perseus cluster. We used deep integral field GCMS data to
revisit NGC 1277 out to an unprecedented radius of 6 kpc (corresponding to ). By using Jeans anisotropic modelling we find a negligible dark
matter fraction within (; two-sigma
confidence level), which is in tension with the expectation. Since the lack of
an extended envelope would reduce dynamical friction and prevent the accretion
of an envelope, we propose that NGC 1277 lost its dark matter very early or
that it was dark matter deficient ab initio. We discuss our discovery in the
framework of recent proposals suggesting that some relic galaxies may result
from dark matter stripping as they fell in and interacted within galaxy
clusters. Alternatively, NGC 1277 might have been born in a high-velocity
collision of gas-rich proto-galactic fragments, where dark matter left behind a
disc of dissipative baryons. We speculate that the relative velocities of
required for the latter process to happen were
possible in the progenitors of the present-day rich galaxy clusters.Comment: Accepted for publication in A&
Galaxy and mass assembly (GAMA): the inferred mass–metallicity relation from z = 0 to 3.5 via forensic SED fitting
We analyse the metallicity histories of ∼4500 galaxies from the GAMA survey at z \u3c 0.06 modelled by the SED-fitting code PROSPECT using an evolving metallicity implementation. These metallicity histories, in combination with the associated star formation histories, allow us to analyse the inferred gas-phase mass–metallicity relation. Furthermore, we extract the mass– metallicity relation at a sequence of epochs in cosmic history, to track the evolving mass–metallicity relation with time. Through comparison with observations of gas-phase metallicity over a large range of redshifts, we show that, remarkably, our forensic SED analysis has produced an evolving mass–metallicity relationship that is consistent with observations at all epochs. We additionally analyse the three-dimensional mass–metallicity–SFR space, showing that galaxies occupy a clearly defined plane. This plane is shown to be subtly evolving, displaying an increased tilt with time caused by general enrichment, and also the slowing down of star formation with cosmic time. This evolution is most apparent at lookback times greater than 7 Gyr. The trends in metallicity recovered in this work highlight that the evolving metallicity implementation used within the SED-fitting code PROSPECT produces reasonable metallicity results over the history of a galaxy. This is expected to provide a significant improvement to the accuracy of the SED-fitting outputs
Metal-THINGS: On the metallicity and ionization of ULX sources in NGC 925
We present an analysis of the optical properties of three Ultra Luminous
X-ray (ULX) sources identified in NGC 925. We use Integral field unit data from
the George Mitchel spectrograph in the context of the Metal-THINGS survey. The
optical properties for ULX-1 and ULX-3 are presented, while the spaxel
associated with ULX-2 had a low S/N, which prevented its analysis. We also
report the kinematics and dimensions of the optical nebula associated with each
ULX using ancillary data from the PUMA Fabry-Perot spectrograph. A BPT analysis
demonstrates that most spaxels in NGC 925 are dominated by star-forming
regions, including those associated with ULX-1 and ULX-3. Using the resolved
gas-phase metallicities, a negative metallicity gradient is found, consistent
with previous results for spiral galaxies, while the ionization parameter tends
to increase radially throughout the galaxy. Interestingly, ULX-1 shows a very
low gas metallicity for its galactocentric distance, identified by two
independent methods, while exhibiting a typical ionization. We find that such
low gas metallicity is best explained in the context of the high-mass X-ray
binary population, where the low-metallicity environment favours active Roche
lobe overflows that can drive much higher accretion rates. An alternative
scenario invoking accretion of a low-mass galaxy is not supported by the data
in this region. Finally, ULX-3 shows both a high metallicity and ionization
parameter, which is consistent with the progenitor being a highly-accreting
neutron star within an evolved stellar population region.Comment: Accepted by Ap
Galaxy classification: deep learning on the OTELO and COSMOS databases
Context. The accurate classification of hundreds of thousands of galaxies
observed in modern deep surveys is imperative if we want to understand the
universe and its evolution. Aims. Here, we report the use of machine learning
techniques to classify early- and late-type galaxies in the OTELO and COSMOS
databases using optical and infrared photometry and available shape parameters:
either the Sersic index or the concentration index. Methods. We used three
classification methods for the OTELO database: 1) u-r color separation , 2)
linear discriminant analysis using u-r and a shape parameter classification,
and 3) a deep neural network using the r magnitude, several colors, and a shape
parameter. We analyzed the performance of each method by sample bootstrapping
and tested the performance of our neural network architecture using COSMOS
data. Results. The accuracy achieved by the deep neural network is greater than
that of the other classification methods, and it can also operate with missing
data. Our neural network architecture is able to classify both OTELO and COSMOS
datasets regardless of small differences in the photometric bands used in each
catalog. Conclusions. In this study we show that the use of deep neural
networks is a robust method to mine the cataloged dataComment: 20 pages, 10 tables, 14 figures, Astronomy and Astrophysics (in
press
The OTELO survey. A case study of [O III]4959,5007 emitters at <z> = 0.83
The OTELO survey is a very deep, blind exploration of a selected region of
the Extended Groth Strip and is designed for finding emission-line sources
(ELSs). The survey design, observations, data reduction, astrometry, and
photometry, as well as the correlation with ancillary data used to obtain a
final catalogue, including photo-z estimates and a preliminary selection of
ELS, were described in a previous contribution. Here, we aim to determine the
main properties and luminosity function (LF) of the [O III] ELS sample of OTELO
as a scientific demonstration of its capabilities, advantages, and
complementarity with respect to other surveys. The selection and analysis
procedures of ELS candidates obtained using tunable filter (TF) pseudo-spectra
are described. We performed simulations in the parameter space of the survey to
obtain emission-line detection probabilities. Relevant characteristics of [O
III] emitters and the LF([O III]), including the main selection biases and
uncertainties, are presented. A total of 184 sources were confirmed as [O III]
emitters at a mean redshift z=0.83. The minimum detectable line flux and
equivalent width (EW) in this ELS sample are 5 10 erg
s cm and 6 \AA, respectively. We are able to constrain the
faint-end slope () of the observed LF([O III]) at
z=0.83. This LF reaches values that are approximately ten times lower than
those from other surveys. The vast majority (84\%) of the morphologically
classified [O III] ELSs are disc-like sources, and 87\% of this sample is
comprised of galaxies with stellar masses of M 10
M.Comment: v1: 16 pages, 6 figures. Accepted in Astronomy \& Astrophysics. v2:
Author added in metadat
Galaxy And Mass Assembly (GAMA): stellar mass growth of spiral galaxies in the cosmic web
We look for correlated changes in stellar mass and star formation rate (SFR) along filaments in the cosmic web by examining the stellar masses and UV-derived SFRs of 1799 ungrouped and unpaired spiral galaxies that reside in filaments. We devise multiple distance metrics to characterize the complex geometry of filaments, and find that galaxies closer to the cylindrical centre of a filament have higher stellar masses than their counterparts near the periphery of filaments, on the edges of voids. In addition, these peripheral spiral galaxies have higher SFRs at a given mass. Complementing our sample of filament spiral galaxies with spiral galaxies in tendrils and voids, we find that the average SFR of these objects in different large-scale environments are similar to each other with the primary discriminant in SFR being stellar mass, in line with previous works. However, the distributions of SFRs are found to vary with large-scale environment. Our results thus suggest a model in which in addition to stellar mass as the primary discriminant, the large-scale environment is imprinted in the SFR as a second-order effect. Furthermore, our detailed results for filament galaxies suggest a model in which gas accretion from voids on to filaments is primarily in an orthogonal direction. Overall, we find our results to be in line with theoretical expectations of the thermodynamic properties of the intergalactic medium in different large-scale environments
The OTELO survey: the star formation rate evolution of low-mass galaxies
We present the analysis of a sample of \ha\,, \hb\ and \oii\ emission line
galaxies from the \otelo\ survey, with masses typically below log(M_*/M_\sun)
\sim 9.4 and redshifts between and 1.43. We study the star
formation rate, star formation rate density, and number density and their
evolution with redshift. We obtain a robust estimate of the specific star
formation rate -- stellar mass relation based on the lowest mass sample
published so far. We also determine a flat trend of the star formation rate
density and number density with redshift. Our results suggest a scenario of no
evolution of the number density of galaxies, regardless of their masses, up to
redshift . This implies a gradual change of the relative importance
of the star forming processes, from high-mass galaxies to low-mass galaxies,
with decreasing redshift. We also find little or no variation of the star
formation rate density in the redshift range of .Comment: 8 pages, 3 figures, accepted for publication in ApJ letter