56 research outputs found
The merger remnant NGC 3610 and its globular cluster system: a large-scale study
We present a photometric study of the prototype merger remnant NGC 3610 and
its globular cluster (GC) system, based on new GEMINI/GMOS and ACS/HST archival
images. Thanks to the large FOV of our GMOS data, larger than previous studies,
we are able to detect a `classical' bimodal GC colour distribution,
corresponding to metal-poor and metal-rich GCs, at intermediate radii and a
small subsample of likely young clusters of intermediate colours, mainly
located in the outskirts. The extent of the whole GC system is settled as about
40 kpc. The GC population is quite poor, about 500 +/- 110 members, that
corresponds to a low total specific frequency S_N ~ 0.8. The effective radii of
a cluster sample are determined, including those of two spectroscopically
confirmed young and metal-rich clusters, that are in the limit between GC and
UCD sizes and brightness. The large-scale galaxy surface-brightness profile can
be decomposed as an inner embedded disc and an outer spheroid, determining for
both larger extents than earlier research (10 kpc and 30 kpc, respectively). We
detect boxy isophotes, expected in merger remnants, and show a wealth of
fine-structure in the surface-brightness distribution with unprecedented
detail, coincident with the outer spheroid. The lack of symmetry in the galaxy
colour map adds a new piece of evidence to the recent merger scenario of NGC
3610.Comment: 14 pages, 16 figures. Accepted for publication in MNRA
Footprints in the sand: What can globular clusters tell us about NGC 4753 past?
NGC 4753 is a bright (M_V approx -22.3) lenticular galaxy. It is a very
interesting target to test different theories of formation of lenticular
galaxies, due to its low-density environment and complex structure. We perform
the first comprehensive study of NGC 4753 globular cluster system (GCS), using
Gemini/GMOS and CTIO/MosaicII images. Our results indicate a rather poor GCS of
approx 1000 members. Its azimuthal distribution follows the shape of the galaxy
bulge. The GC colour distribution is peculiar, presenting an intermediate
subpopulation in addition to blue and red ones. This intermediate subgroup can
be explained by a single stellar population with an age of 1.5-3 Gyr and 0.5-1
Z_o. The GC specific frequency S_N = 1.3+/-0.15 is surprisingly low for a
galaxy of its class. The GC luminosity function (GCLF) is also peculiar, with
an excess of bright GCs compared to the expected gaussian distribution. The
underlying galaxy body has significant substructure, with remnants of spiral
arms, dust filaments, and isophote twisting. This, and the fact that NGC 4753
hosted two type Ia SNe, support the possibility that the intermediate GC
subpopulation may have originated during a recent merger, 1-3 Gyr ago.Comment: 10 pages, 10 figures, accepted on MNRA
Ultra-Compact Dwarfs around NGC 3268
We present radial velocities (from Gemini/GMOS) of the second sample of
ultra-compact dwarfs (UCDs) and bright globular clusters (GCs) in the Antlia
cluster. Twenty-three objects are located around the giant elliptical NGC 3268,
and one is close to the fainter lenticular NGC 3273. Together with previously
found UCDs around NGC 3258 a total of 35 UCDs and bright GCs has been now
identified in the Antlia cluster. Their colours and magnitudes are compared
with those of the nuclei of dE,N galaxies already confirmed as Antlia members.
For a subsample that lie on ACS images and are brighter than M_V = -9 mag, the
effective radii (R_eff) have been measured, the maximum radius being
approximately 10 pc. In addition to the radial velocity sample, we find 10
objects in the magnitude range corresponding to GCs but with 10 < R_eff < 17
pc, resembling the so-called `extended clusters'. By number and magnitude, the
new UCDs fit to the GC luminosity function, supporting their interpretation as
bright GCs. Additionally, we use a tracer mass estimator to calculate the mass
enclosed up to ~47 kpc from NGC 3268, which results in 2.7 x 10^12 M_o.Comment: 10 pages, 5 figures, to be published in MNRA
Galaxy populations in the Antlia cluster - III. Properties of faint early-type galaxies
(Abridge) We present a new analysis of the early-type galaxy population in
the central region of the Antlia cluster, focusing on the faint systems like
dwarf ellipticals (dE) and dwarf spheroidals (dSph). We confirm 22 early-type
galaxies as Antlia members, using GEMINI-GMOS and MAGELLAN-MIKE spectra. Among
them, 2 belong to the rare type of compact ellipticals (cE), and 5 are new
faint dwarfs that had never been catalogued before. In addition, we present 16
newly identified low surface brightness galaxy candidates, almost half of them
displaying morphologies consistent with being Antlia's counterparts of Local
Group dSphs, that extend the faint luminosity limit of our study down to MB =
-10.1 (BT = 22.6) mag. We built an improved CMR in the Washington photometric
system, i.e. integrated T1 magnitudes versus (C - T1) colours, which extends
\sim 4 mag faintwards the limit of spectroscopically confirmed Antlia members.
When only confirmed early-type members are considered, this relation extends
over 10 mag in luminosity with no apparent change in slope or increase in
colour dispersion towards its faint end. The intrinsic colour scatter of the
relation is compared with those reported for other clusters of galaxies; we
argue that it is likely that the large scatter of the CMR, usually reported at
faint magnitudes, is mostly due to photometric errors along with an improper
membership/morphological classification. The distinct behaviour of the
luminosity versus mean effective surface brightness relation at the bright and
faint ends is analyzed, while it is confirmed that dE galaxies on the same
relation present a very similar effective radius, regardless of their colour.
The projected spatial distribution of the member sample confirms the existence
of two groups in Antlia, each one dominated by a giant elliptical galaxy and
with one cE located close to each giant.Comment: 19 pages, 9 figures, 5 tables. Accepted for publication in MNRA
Ultra-Compact Dwarfs around NGC 3258 in Antlia
We present the first compact stellar systems with luminosities in the range
of ultra-compact dwarfs (UCDs), discovered in the Antlia galaxy cluster (-10.5
< M_V < -11.6). The magnitude limit between UCDs and globular clusters (CGs) is
discussed. By means of imaging from VLT (FORS1), CTIO (MOSAIC), and the HST
(ACS) archive, eleven UCDs/bright GCs are selected on the basis of photometry
and confirmed as Antlia members through radial velocities measured on new
GEMINI (GMOS-S) spectra. In addition, nine UCD candidates are identified taking
into account properties derived from their surface brightness profiles. All of
them, members and candidates, are located in the proximity of NGC\,3258, one of
the two brightest elliptical galaxies in the cluster core. Antlia UCDs in this
sample present absolute magnitudes fainter than M_V ~ -11.6 mag and most of
them have colours within the blue GC range, falling only two within the red GC
range. Effective radii measured for the ones lying on the ACS field are in the
range R_eff = 3 - 11 pc and are similar to equivalent objects in other
clusters, obtained from the literature. The UCD sample shares the same
behaviour on the size-luminosity plane: a linear relation between R_eff and M_V
is present for UCDs brighter than M_V ~ -10.5 - -11 mag while no trend is
detected for fainter ones, that have an approximately constant R_eff. The
projected spatial distribution of UCDs, GCs and X-ray emission points to an
ongoing merger between two Antlia groups, dominated by NGC 3258 and NGC 3268.
Nuclei of dwarf elliptical galaxies and blue UCDs share the same locus on the
colour-magnitude diagram, supporting the hypothesis that some blue UCDs may be
remnants of stripped nucleated dwarfs.Comment: 15 pages, 13 figures Accepted for publication in MNRA
J-PLUS : a catalogue of globular cluster candidates around the M 81/M 82/NGC 3077 triplet of galaxies
Globular clusters (GCs) are proxies of the formation assemblies of their host galaxies. However, few studies exist targeting GC systems of spiral galaxies up to several effective radii. Through 12-band Javalambre Photometric Local Universe Survey (J-PLUS) imaging, we study the point sources around the Mâ81/Mâ82/NGCâ3077 triplet in search of new GC candidates. We develop a tailored classification scheme to search for GC candidates based on their similarity to known GCs via a principal component analysis projection. Our method accounts for missing data and photometric errors. We report 642 new GC candidates in a region of 3.5 deg2 around the triplet, ranked according to their Gaia astrometric proper motions when available. We find tantalizing evidence for an overdensity of GC candidate sources forming a bridge connecting Mâ81 and Mâ82. Finally, the spatial distribution of the GC candidates (g â i) colours is consistent with halo/intra-cluster GCs, i.e. it gets bluer as they get further from the closest galaxy in the field. We further employ a regression-tree-based model to estimate the metallicity distribution of the GC candidates based on their J-PLUS bands. The metallicity distribution of the sample candidates is broad and displays a bump towards the metal-rich end. Our list increases the population of GC candidates around the triplet by threefold, stresses the usefulness of multiband surveys in finding these objects, and provides a testbed for further studies analysing their spatial distribution around nearby (spirals) galaxies
Coenzyme Q10 supplementation improves metabolic parameters, liver function and mitochondrial respiration in rats with high doses of atorvastatin and a cholesterol-rich diet
Viral RNA load in plasma is associated with critical illness and a dysregulated host response in COVIDâ19
Background. COVID-19 can course with respiratory and extrapulmonary disease. SARS-CoV-2 RNA is detected in respiratory samples but also in blood, stool and urine. Severe COVID-19 is characterized by a dysregulated host response to this virus. We studied whether viral RNAemia or viral RNA load in plasma is associated with severe COVID-19 and also to this dysregulated response.
Methods. A total of 250 patients with COVID-19 were recruited (50 outpatients, 100 hospitalized ward patients and 100 critically ill). Viral RNA detection and quantification in plasma was performed using droplet digital PCR, targeting the N1 and N2 regions of the SARS-CoV-2 nucleoprotein gene. The association between SARS-CoV-2 RNAemia and viral RNA load in plasma with severity was evaluated by multivariate logistic regression. Correlations between viral RNA load and biomarkers evidencing dysregulation of host response were evaluated by calculating the Spearman correlation coefficients.
Results. The frequency of viral RNAemia was higher in the critically ill patients (78%) compared to ward patients (27%) and outpatients (2%) (pâ<â0.001). Critical patients had higher viral RNA loads in plasma than non-critically ill patients, with non-survivors showing the highest values. When outpatients and ward patients were compared, viral RNAemia did not show significant associations in the multivariate analysis. In contrast, when ward patients were compared with ICU patients, both viral RNAemia and viral RNA load in plasma were associated with critical illness (OR [CI 95%], p): RNAemia (3.92 [1.183â12.968], 0.025), viral RNA load (N1) (1.962 [1.244â3.096], 0.004); viral RNA load (N2) (2.229 [1.382â3.595], 0.001). Viral RNA load in plasma correlated with higher levels of chemokines (CXCL10, CCL2), biomarkers indicative of a systemic inflammatory response (IL-6, CRP, ferritin), activation of NK cells (IL-15), endothelial dysfunction (VCAM-1, angiopoietin-2, ICAM-1), coagulation activation (D-Dimer and INR), tissue damage (LDH, GPT), neutrophil response (neutrophils counts, myeloperoxidase, GM-CSF) and immunodepression (PD-L1, IL-10, lymphopenia and monocytopenia).
Conclusions. SARS-CoV-2 RNAemia and viral RNA load in plasma are associated with critical illness in COVID-19. Viral RNA load in plasma correlates with key signatures of dysregulated host responses, suggesting a major role of uncontrolled viral replication in the pathogenesis of this disease.This work was supported by awards from the Canadian Institutes of Health Research, the Canadian 2019 Novel Coronavirus (COVID-19) Rapid Research Funding initiative (CIHR OV2 â 170357), Research Nova Scotia (DJK), Atlantic Genome/Genome Canada (DJK), Li-Ka Shing Foundation (DJK), Dalhousie Medical Research Foundation (DJK), the âSubvenciones de concesiĂłn directa para proyectos y programas de investigaciĂłn del virus SARSâCoV2, causante del COVIDâ19â, FONDOâCOVID19, Instituto de Salud Carlos III (COV20/00110, CIBERES, 06/06/0028), (AT) and fnally by the âConvocatoria extraordinaria y urgente de la Gerencia Regional de Salud de Castilla y LeĂłn, para la fnanciaciĂłn de proyectos de investigaciĂłn en enfermedad COVID-19â (GRS COVID 53/A/20) (CA). DJK is a recipient of the Canada Research Chair in Translational Vaccinology and Infammation. APT was funded by the Sara Borrell Research Grant CD018/0123 funded by Instituto de Salud Carlos III and co-fnanced by the European Development Regional Fund (A Way to Achieve Europe programme). The funding sources did not play any role neither in the design of the study and collection, not in the analysis, in the interpretation of data or in writing the manuscript
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