ABSTRACT
The age–metallicity relation (AMR) is a fundamental tool for constraining the chemical evolution of the Galactic disc. In this work, we analyse the observational properties of this relation ...using binary stars that have not interacted consisting of a white dwarf (WD) – from which we can derive the total age of the system – and a main sequence (MS) star – from which we can derive the metallicity as traced by the Fe/H abundances. Our sample consists of 46 widely separated, but unresolved spectroscopic binaries identified within the Sloan Digital Sky Survey, and 189 WD plus MS common proper motion pairs identified within the second data release of Gaia. This is currently the largest WD sample for which the metallicity of their progenitors have been determined. We find a flat AMR displaying a scatter of Fe/H abundances of approximately ±0.5 dex around the solar metallicity at all ages. This independently confirms the lack of correlation between age and metallicity in the solar neighbourhood that is found in previous studies focused on analysing single MS stars and open clusters.
Context.
Core extremely red quasars (core ERQ) have been proposed to represent an intermediate evolutionary phase in which a heavily obscured quasar blows out the circumnuclear interstellar medium ...with very energetic outflows before it becomes an optical quasar.
Aims.
We investigate whether the properties of core ERQ fit the AGN orientation-based unification scenario.
Methods.
We revised the general UV and optical emission line properties of core ERQ in the context of the orientation-based scenario. We used diagnostic diagrams based on UV emission line ratios and UV-to-optical line kinematic information to compare the physical and kinematic gas properties of core ERQ with those of other luminous narrow- and broad-line AGN. In particular, we provide a revised comparison of the OIII kinematics in 21 core ERQ (20 from Perrotta et al. 2019, MNRAS, 488, 4126 and SDSS J171420.38+414815.7, based on GTC EMIR near-infrared spectroscopy) with other samples of quasars with matching luminosity with the aim of evaluating whether core ERQ host the most extreme OIII outflows.
Results.
The UV line ratios suggest that the physical properties (e.g., density and metallicity) of the ionised gas in core ERQ are similar to those observed in the broad-line region of blue nitrogen-loud quasars. The OIII outflow velocities of core ERQ are on average consistent with those of very luminous blue type 1 quasars, although extreme outflows are much more frequent in core ERQ. These similarities can be explained in the context of the AGN unification model under the assumption that core ERQ are viewed with an intermediate orientation between type 2 (edge-on) and type 1 (face-on) quasars.
Conclusions.
We propose that core ERQ are very luminous but otherwise normal quasars viewed at an intermediate orientation. This orientation allows a direct view of the outer part of the large broad-line region from which core ERQ UV line emission originates; the extreme OIII outflow velocities are instead a consequence of the very high luminosity of core ERQ.
The cool white dwarf WD 1856+534 was found to be transited by a Jupiter-sized object with a mass at or below 14
M
Jup
. We used the GTC telescope to obtain and analyse the photometry and ...low-resolution spectroscopy of six transits of WD 1856+534 b, with the intention of deriving the slope of the transmission spectrum. Such a slope, assuming a cloud-free atmosphere dominated by Rayleigh scattering of the particles in its atmosphere, could be translated into an estimation of the mass of WD 1856+534 b. However, the resultant transmission spectrum is essentially flat and therefore permits only the determination of lower mass limits of 2.4
M
Jup
at the 2
σ
level, or 1.6
M
Jup
at 3
σ
. These limits have implications for some of the formation scenarios proposed for the object. We elaborate on the potential effects of clouds and hazes in our estimations, based on previous studies of Jupiter and Titan. In addition, we detected an H
α
absorption feature in the combined spectrum of the host white dwarf, which leads to the assignation of a DA classification and allows the derivation of an independent set of atmospheric parameters. Furthermore, the epochs of five transits were measured with sub-second precision, which demonstrates that additional objects more massive than ≈5
M
Jup
and with periods longer than O(100) days could be detected through the light-time effect.
Contaminants of emerging concern (CEC) are still under research given the vast diversity of compounds reaching freshwater ecosystems and adverse effects they might cause. In this study, the ...environmental fate of 73 CEC, comprising sweeteners, stimulants and several pharmaceutical therapeutic classes, and changes in fluvial biofilm photosynthetic parameters were evaluated in a semi-arid urban river receiving diffuse and point sources of pollution (Suquía river, Argentina). Out of the 37 CEC detected, 30 were quantified in surface water (n.d. – 9826 ng/L), 10 in biofilm (n.d. – 204 ng/gd.w.) and 9 in the clay fraction of sediments (n.d. – 64 ng/gd.w.). CEC distribute differently among the 3 matrices: water phase presents the biggest diversity of compounds (14 CEC families), being analgesic/anti-inflammatories the most abundant family. Antibiotics largely predominated in biofilms (7 CEC families), while the stimulant caffeine and some antibiotics where the most abundant in sediments (6 CEC families). Different CEC accumulated in biofilms and sediments upstream and downstream the city, and big shifts of biofilm community occurred downstream WWTP. The shift of biofilm community upstream (F0 > 0) and downstream the WWTP (F0 = 0) shows a sensitive response of F0 to the impact of WWTP. Biofilm photosynthetic parameters responded in less impacted urban sites (sites 1, 2 and 3), where significant correlations were found between ketoprofen and some antibiotics and biofilm parameters. The diversity and amount of CEC found in the urban section of Suquía river alert to the magnitude of point and non-point sources of pollution.
Display omitted
•Emerging contaminants and changes in biofilm parameters in an urban river.•Thirty EC in surface water (up to μg/L), 10 in biofilm, 9 in sediments (ng/g d.w.).•Different families predominated in water, biofilm and sediments.•Photosynthetic biofilm parameters responded in less impacted urban sites.•EC and biofilm parameters are proposed as markers of point and diffuse pollution.
Context.
A rich population of low-mass brown dwarfs and isolated planetary mass objects has been reported in the Upper Scorpius and Ophiuchus star-forming complex.
Aims.
We investigate the ...membership, nature, and properties of 17 of these isolated planetary mass candidates using low-resolution near-infrared spectra.
Methods.
We investigated the membership by looking for evidence of their youth using four diagnostics: the slope of the continuum between the
J
and
Ks
band, the
H
cont
, and the TLI-g gravity-sensitive indices. In addition, we compared the spectra to young and field (old) M and L-dwarf standards.
Results.
All the targets but one are confirmed as young ultracool objects, with spectral types between L0 and L6 and masses in the range 0.004–0.013
M
⊙
, according to evolutionary models. The status of the last target is unclear at this point.
Conclusions.
Only one possible contaminant has been identified among the 17 targets, suggesting that the contamination level of the original sample must be low (≲6%).
We investigate the potential of submm-mm and submm-mm-radio photometric redshifts using a sample of mm-selected sources as seen at 250, 350 and 500μm by the SPIRE instrument on Herschel. From a ...sample of 63 previously identified mm sources with reliable radio identifications in the Great Observatories Origins Deep Survey North and Lockman Hole North fields, 46 (73 per cent) are found to have detections in at least one SPIRE band. We explore the observed submm/mm colour evolution with redshift, finding that the colours of mm sources are adequately described by a modified blackbody with constant optical depth τ= (ν/nu
0)β, where β=+1.8 and ν0=c/100 μm. We find a tight correlation between dust temperature and IR luminosity. Using a single model of the dust temperature and IR luminosity relation, we derive photometric redshift estimates for the 46 SPIRE-detected mm sources. Testing against the 22 sources with known spectroscopic or good quality optical/near-IR photometric redshifts, we find submm/mm photometric redshifts offer a redshift accuracy of |Δz|/(1 +z) = 0.16 (〈|Δz|〉= 0.51). Including constraints from the radio-far-IR correlation, the accuracy is improved to |Δz|/(1 +z) = 0.15 (〈|Δz|〉= 0.45). We estimate the redshift distribution of mm-selected sources finding a significant excess at z > 3 when compared to ∼ 850 μm selected samples.
Context. A set of 20 extremely red galaxies at 2.5 ≤ zphot. ≤ 3.8 with photometric features of old passive-evolving galaxies without dust, with stellar masses of ~ 1011M⊙, have colors that could be ...related to passive-evolving galaxies with mean ages larger than 1 Gyr. This suggests they have been formed, on average, when the Universe was very young (<1 Gyr). Aims. We provide new estimates for the stellar content of these 20 galaxies, with a deeper analysis for two of them that includes spectroscopy. Methods. We obtained, with the GRANTECAN-10.4 m, ultraviolet rest-frame spectra of two galaxies and analyzed them together with photometric data. The remaining 18 galaxies are analyzed only with photometry. We fit the data with models of a single-burst stellar population (SSP), combinations of two SSPs, as well as with extended star formation. Results. Fits based on one SSP do not provide consistent results for the blue and red wavelengths. Moreover, the absence in the spectra of a break at ~ 2 × 103 Å indicates that a rather young component is necessary. Using two SSPs we can match the photometric and spectroscopic data, with the bulk of the stellar population being very old (several Gyr) and the remaining contribution (<5% of stellar mass fraction) from a young, likely residual star formation component with age ≲ 0.1 Gyr. Exponentially decaying extended star formation (τ) models improve slightly the fits with respect to the single burst model, but they are considerably worse than the two SSP based fits, further supporting the residual star formation scenario. Conclusions. The fact that one SSP cannot match these early-type galaxies highlights the limitations for the use of age estimators based on single lines or breaks, such as the Balmer break used in cosmic chronometers, thus questioning this approach for cosmological purposes.
Context.
4C12.50 (IRAS 13451+1232) at
z
= 0.122 is an ultraluminous infared radio galaxy that has often been proposed as a prime candidate for the link between ultraluminous infared galaxies and ...young radio galaxies. It is also an interesting target to investigate whether and how radio-induced feedback affects the evolution of galaxies in the early phases of radio activity.
Aims.
We study, in detail for the first time, the hot (≥1500 K) molecular gas in 4C12.50. The potential impact of the radio jet on this gas phase, as well as on the star formation activity, are investigated. We also study the ionised (including coronal) gas as traced by the near-infrared lines.
Methods.
Using near-infrared long slit spectroscopy obtained with EMIR on GTC and X-shooter on VLT, we analyse the emission line spectrum of the ionised, coronal, and, specially, the hot molecular gas in the western nucleus hosting the compact radio jet. Based on high spatial resolution ALMA CO(2–1) data, we also revise the location of 4C12.50 in the Kennicutt-Schmidt diagram in order to investigate whether star formation is suppressed.
Results.
4C12.50 hosts (2.1 ± 0.4) × 10
4
M
⊙
of hot molecular gas. An unusually high rotational temperature
T
rot
= 3020 ± 160 K is inferred. The molecular gas mass obeys a power-law temperature distribution, d
M
H2
/d
T
∝
T
−5
, from
T
∼ 300 K and up to ∼3000 K. Both results support the idea that shocks (probably induced by the radio jet) contribute to the heating and excitation of the hot molecular gas. A molecular outflow is not detected. The coupling of the outflowing ionised and neutral outflows with the hot molecular gas is poor. Contrary to other studies, we claim that there is no evidence for star formation suppression in this object.
Conclusions.
If radio-induced feedback can regulate the star formation activity in galaxies, 4C12.50 is a promising candidate to reveal this phenomenon in action. However, we find no solid evidence for a current or past impact of this mechanism on the evolution of this system, neither by clearing out the dusty central cocoon efficiently, nor by suppressing the star formation activity.
Abstract
The Herschel Multi-tiered Extragalactic Survey (HerMES) is a legacy programme designed to map a set of nested fields totalling ∼380 deg2. Fields range in size from 0.01 to ∼20 deg2, using ...the Herschel-Spectral and Photometric Imaging Receiver (SPIRE) (at 250, 350 and 500 μm) and the Herschel-Photodetector Array Camera and Spectrometer (PACS) (at 100 and 160 μm), with an additional wider component of 270 deg2 with SPIRE alone. These bands cover the peak of the redshifted thermal spectral energy distribution from interstellar dust and thus capture the reprocessed optical and ultraviolet radiation from star formation that has been absorbed by dust, and are critical for forming a complete multiwavelength understanding of galaxy formation and evolution.
The survey will detect of the order of 100 000 galaxies at 5σ in some of the best-studied fields in the sky. Additionally, HerMES is closely coordinated with the PACS Evolutionary Probe survey. Making maximum use of the full spectrum of ancillary data, from radio to X-ray wavelengths, it is designed to facilitate redshift determination, rapidly identify unusual objects and understand the relationships between thermal emission from dust and other processes. Scientific questions HerMES will be used to answer include the total infrared emission of galaxies, the evolution of the luminosity function, the clustering properties of dusty galaxies and the properties of populations of galaxies which lie below the confusion limit through lensing and statistical techniques.
This paper defines the survey observations and data products, outlines the primary scientific goals of the HerMES team, and reviews some of the early results.
Background and purpose
Spain has been one of the countries more heavily stricken by SARS‐CoV‐2, which has had huge implications for stroke care. The aim was to analyse the impact of the COVID‐19 ...epidemic outbreak on reperfusion therapies for acute ischaemic stroke in the northwest of Spain.
Methods
This was a Spanish multicentre retrospective observational study based on data from tertiary hospitals of the NORDICTUS network. All patients receiving reperfusion therapy for ischaemic stroke between 30 December 2019 and 3 May 2020 were recorded, and their baseline, clinical and radiological characteristics, extra‐ and intra‐hospital times of action, Code Stroke activation pathway, COVID‐19 status, reperfusion rate, and short‐term outcome before and after the setting of the emergency state were analysed.
Results
A total of 796 patients received reperfusion therapies for ischaemic stroke. There was a decrease in the number of patients treated per week (46.5 patients per week vs. 39.0 patients per week, P = 0.043) and a delay in out‐of‐hospital (95.0 vs. 110.0 min, P = 0.001) and door‐to‐needle times (51.0 vs. 55.0, P = 0.038). Patients receiving endovascular therapy obtained less successful reperfusion rates (92.9% vs. 86.6%, P = 0.016). COVID‐19 patients had more in‐hospital mortality.
Conclusion
A decrease in the number of patients benefiting from reperfusion therapies was found, with a delay in out‐of‐hospital and door‐to‐needle times and worse reperfusion rates in northwest Spain. COVID‐19 patients had more in‐hospital mortality.
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