Abstract
We present a blind time-delay strong lensing (TDSL) cosmographic analysis of the doubly imaged quasar SDSS 1206+4332 . We combine the relative time delay between the quasar images, Hubble ...Space Telescope imaging, the Keck stellar velocity dispersion of the lensing galaxy, and wide-field photometric and spectroscopic data of the field to constrain two angular diameter distance relations. The combined analysis is performed by forward modelling the individual data sets through a Bayesian hierarchical framework, and it is kept blind until the very end to prevent experimenter bias. After unblinding, the inferred distances imply a Hubble constant H0 = 68.8$^{+5.4}_{-5.1}$ km s−1 Mpc−1, assuming a flat Λ cold dark matter cosmology with uniform prior on Ωm in 0.05, 0.5. The precision of our cosmographic measurement with the doubly imaged quasar SDSS 1206+4332 is comparable with those of quadruply imaged quasars and opens the path to perform on selected doubles the same analysis as anticipated for quads. Our analysis is based on a completely independent lensing code than our previous three H0LiCOW systems and the new measurement is fully consistent with those. We provide the analysis scripts paired with the publicly available software to facilitate independent analysis (footnote with link to www.h0licow.org). The consistency between blind measurements with independent codes provides an important sanity check on lens modelling systematics. By combining the likelihoods of the four systems under the same prior, we obtain H0 = 72.5$^{+2.1}_{-2.3}$ km s−1 Mpc−1. This measurement is independent of the distance ladder and other cosmological probes.
Biological remediation technologies are an environmentally friendly approach for the treatment of polluted soils. This study evaluated through a pot experiment four bioremediation strategies: a) ...natural attenuation, b) phytoremediation with alfalfa (Medicago sativa L.), c) bioaugmentation with Pseudomonas aeruginosa and d) bioaugmentation-assisted phytoremediation, for the treatment of a co-contaminated soil presenting moderate levels of heavy metals (Cu, Pb and Zn at 87, 100 and 110mgkg−1 DW, respectively) and petroleum hydrocarbons (3800mgkg−1 DW). As demonstrated by plant biomass and selected physiological parameters alfalfa plants were able to tolerate and grow in the co-contaminated soil, especially when soil was inoculated with P. aeruginosa, which promoted plant growth (56% and 105% increase for shoots and roots, respectively) and appeared to alleviate plant stress. The content of heavy metals in alfalfa plants was limited and followed the order: Zn>Cu>Pb. Heavy metals were mainly concentrated in plant roots and were poorly translocated, favouring their stabilization in the root zone. Bioaugmentation of planted soil with P. aeruginosa generally led to a decrease of plant metal concentration and translocation. The highest degree of total petroleum hydrocarbon removal was obtained for bioaugmentation-assisted phytoremediation treatment (68%), followed by bioaugmentation (59%), phytoremediation (47%) and natural attenuation (37%). The results of this study demonstrated that the combined use of plant and bacteria was the most advantageous option for the treatment of the present co-contaminated soil, as compared to natural attenuation, bioaugmentation or phytoremediation applied alone.
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•Knowledge on biological remediation of co-contaminated soils is not sufficient.•Bioremediation strategies were compared through a pot experiment in growth-chamber.•Alfalfa was able to tolerate and grow in a moderately co-contaminated soil.•Pseudomonas aeruginosa promoted plant growth and alleviated plant stress.•Alfalfa-Pseudomonas aeruginosa association enhanced petroleum hydrocarbon removal.
The projected virial theorem is applied to the case of multiple stellar populations in the nearby dwarf spheroidal galaxies. As each population must reside in the same gravitational potential, this ...provides strong constraints on the nature of the dark matter halo. We derive necessary conditions for two populations with Plummer or exponential surface brightnesses to reside in a cusped Navarro-Frenk-White (NFW) halo. We apply our methods to the Sculptor dwarf spheroidal, and show that there is no NFW halo compatible with the energetics of the two populations. The dark halo must possess a core radius of ~120 pc for the virial solutions for the two populations to be consistent. This conclusion remains true, even if the effects of flattening or self-gravity of the stellar populations are included.
Abstract
We use data from the HST Coma Cluster Treasury program to assess the richness of the globular cluster systems (GCSs) of 54 Coma ultra-diffuse galaxies (UDGs), 18 of which have a half-light ...radius exceeding 1.5 kpc. We use a hierarchical Bayesian method tested on a large number of mock data sets to account consistently for the high and spatially varying background counts in Coma. These include both background galaxies and intra-cluster globular clusters (ICGCs), which are disentangled from the population of member globular clusters (GCs) in a probabilistic fashion. We find no candidate for a GCS as rich as that of the Milky Way, our sample has GCSs typical of dwarf galaxies. For the standard relation between GCS richness and halo mass, 33 galaxies have a virial mass Mvir ≤ 1011 M⊙ at 90 per cent probability. Only three have Mvir > 1011 M⊙ with the same confidence. The mean colour and spread in colour of the UDG GCs are indistinguishable from those of the abundant population of ICGCs. The majority of UDGs in our sample are consistent with the relation between stellar mass and GC richness of ‘normal’ dwarf galaxies. Nine systems, however, display GCSs that are richer by a factor of 3 or more (at 90 per cent probability). Six of these have sizes ≲1.4 kpc. Our results imply that the physical mechanisms responsible for the extended size of the UDGs and for the enhanced GC richness of some cluster dwarfs are at most weakly correlated.
The core size of the Fornax dwarf spheroidal Amorisco, N. C; Agnello, A; Evans, N. W
Monthly notices of the Royal Astronomical Society. Letters,
02/2013, Volume:
429, Issue:
1
Journal Article
Peer reviewed
Open access
We exploit the detection of three distinct stellar subpopulations in the red giant branch of the Fornax dwarf spheroidal to probe its density distribution. This allows us to resolve directly the ...evolution of the dark matter mass profile with radius. We find that a cored dark matter halo is consistent well within 1σ with all three stellar populations, and for the first time we are able to put constraints on the core size of such a halo. With respect to previous work, we do not strengthen the statistical exclusion of a dark matter cusp in Fornax, but we find that Navarro-Frenk-White haloes would be required to have unrealistically large scale radii in order to be compatible with the data, hence low values of the concentration parameter. We are then forced to conclude that the Fornax dwarf spheroidal sits within a dark matter halo having a constant-density core, with a core size of r
0 = 1+ 0.8
− 0.4 kpc.
Context. We present the first public data release of the VISTA EXtension to Auxiliary Surveys (VEXAS), comprising nine cross-matched multi-wavelength photometric catalogues where each object has a ...match in at least two surveys. Aims. Our aim is to provide spatial coverage that is as uniform as possible in the multi-wavelength sky and to provide the astronomical community with reference magnitudes and colours for various scientific uses: object classification (e.g. quasars, galaxies, and stars; high-z galaxies, white dwarfs); photometric redshifts of large galaxy samples; searches of exotic objects (e.g. extremely red objects and lensed quasars). Methods. We cross-matched the wide-field VISTA catalogues (the VISTA Hemisphere Survey and the VISTA Kilo Degree Infrared Galaxy Survey) with the AllWISE mid-infrared Survey, requiring a match within 10″. We have further matched this table with X-ray and radio data (ROSAT, XMM, SUMSS). We also performed a second cross-match between VISTA and AllWISE, with a smaller matching radius (3″), including WISE magnitudes. We then cross-matched this resulting table (≈138 × 106 objects) with three photometric wide-sky optical deep surveys (DES, SkyMapper, PanSTARRS). We finally included matches to objects with spectroscopic follow-up by the SDSS and 6dFGS. Results. To demonstrate the power of all-sky multi-wavelength cross-match tables, we show two examples of scientific applications of VEXAS, in particular using the publicly released tables to discover strong gravitational lenses (beyond the reach of previous searches) and to build a statistically large sample of extremely red objects. Conclusions. The VEXAS catalogue is currently the widest and deepest public optical-to-IR photometric and spectroscopic database in the southern hemisphere.
ABSTRACT
We report the spectroscopic follow-up of 175 lensed quasar candidates selected using Gaia Data Release 2 observations following Paper III of this series. Systems include 86 confirmed lensed ...quasars and a further 17 likely lensed quasars based on imaging and/or similar spectra. We also confirm 11 projected quasar pairs and 11 physical quasar pairs, while 25 systems are left as unclassified quasar pairs – pairs of quasars at the same redshift, which could be either distinct quasars or potential lensed quasars. Especially interesting objects include eight quadruply imaged quasars of which two have BAL sources, an apparent triple, and a doubly lensed LoBaL quasar. The source redshifts and image separations of these new lenses range between 0.65–3.59 and 0.78–6.23 arcsec, respectively. We compare the known population of lensed quasars to an updated mock catalogue at image separations between 1 and 4 arcsec, showing a very good match at z < 1.5. At z > 1.5, only 47 per cent of the predicted number are known, with 56 per cent of these missing lenses at image separations below 1.5 arcsec. The missing higher redshift, small-separation systems will have fainter lensing galaxies, and are partially explained by the unclassified quasar pairs and likely lenses presented in this work, which require deeper imaging. Of the 11 new reported projected quasar pairs, 5 have impact parameters below 10 kpc, almost tripling the number of such systems, which can probe the innermost regions of quasar host galaxies through absorption studies. We also report four new lensed galaxies discovered through our searches, with source redshifts ranging from 0.62 to 2.79.
Metallurgical exploitation originates metal-rich by-products termed slags, which are often disposed in the environment being a source of heavy metal pollution. Despite the environmental risk that ...this may pose for living organisms, little is known about the impact of slags on biotic components of the ecosystem like plants and rhizosphere microbial communities.
In this study, metal-rich (Cu, Pb, Zn) granulated slags (GS) derived from Cu production process, were used for a leaching test in the presence of the soil pore solution, showing that soil solution enhanced the release of Cu from GS. A pot experiment was conducted using as growing substrate for sunflower (Helianthus annuus) a 50% w/w mix of an agricultural soil and GS. Bioavailability of metals in soil was, in increasing order: Pb < Zn < Cu. Sunflower was able to grow in the presence of GS and accumulated metals preferentially in above-ground tissues. Microbial diversity was assessed in rhizosphere and bulk soil using community level physiological profiling (CLPP) and 16S rRNA gene based denaturing gradient gel electrophoresis (DGGE) analyses, which demonstrated a shift in the diversity of microbial communities induced by GS.
Overall, these results suggest that metallurgical wastes should not be considered inert when dumped in the soil. Implications from this study are expected to contribute to the development of sustainable practices for the management of pyrometallurgical slags, possibly involving a phytomanagement approach.
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•Soil solution enhances the leaching of Cu from metallurgical slags.•Cu is the most bioavailable metal in the soil/slag mix, followed by Zn and Pb.•Sunflower was able to grow in the soil/slag mix, tolerating metal rich slags.•Sunflower accumulated Cu, Pb and Zn in the above-ground tissues.•Slags have a role in shaping the diversity of soil microbial communities.
The contamination of soils with inorganic and organic pollutants is a diffuse environmental issue of significant relevance. Phytoremediation has been proposed as an economically feasible and ...sustainable remediation technology even if low bioavailability of contaminants constitutes one of the main limitations restricting the success of phytotechnologies. To overcome this constraint the addition of biodegradable amendments has been recently proposed in alternative to synthetic ones. This article presents an overview of two types of biodegradable soil amendments: low molecular weight organic acids and surfactants, evaluating the feasibility of their application in the frame of soil remediation throughout enhanced phytoremediation.
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