101 research outputs found
F-VIPGI: a new adapted version of VIPGI for FORS2 spectroscopy. Application to a sample of 16 X-ray selected galaxy clusters at 0.6 < z < 1.2
The goal of this paper is twofold. Firstly, we present F-VIPGI, a new version
of the VIMOS Interactive Pipeline and Graphical Interface (VIPGI) adapted to
handle FORS2 spectroscopic data. Secondly, we investigate the
spectro-photometric properties of a sample of galaxies residing in distant
X-ray selected galaxy clusters, the optical spectra of which were reduced with
this new pipeline. We provide basic technical information about the innovations
of the new software and, as a demonstration of the capabilities of the new
pipeline, we show results obtained for 16 distant (0.65 < z < 1.25) X-ray
luminous galaxy clusters selected within the XMM-Newton Distant Cluster
Project. We performed a spectral indices analysis of the extracted optical
spectra of their members, based on which we created a library of composite high
signal-to-noise ratio spectra representative of passive and star-forming
galaxies residing in distant galaxy clusters. The spectroscopic templates are
provided to the community in electronic form. By comparing the
spectro-photometric properties of our templates with the local and distant
galaxy population residing in different environments, we find that passive
galaxies in clusters appear to be well evolved already at z = 0.8 and even more
so than the field galaxies at similar redshift. Even though these findings
would point toward a significant acceleration of galaxy evolution in densest
environments, we cannot exclude the importance of the mass as the main
evolutionary driving element either. The latter effect may indeed be justified
by the similarity of our composite passive spectrum with the luminous red
galaxies template at intermediate redshift.Comment: 15 pages, 15 figures, in press on Astronomy and Astrophysic
The reversal of the SF-density relation in a massive, X-ray selected galaxy cluster at z=1.58: results from Herschel
Dusty, star-forming galaxies have a critical role in the formation and
evolution of massive galaxies in the Universe. Using deep far-infrared imaging
in the range 100-500um obtained with the Herschel telescope, we investigate the
dust-obscured star formation in the galaxy cluster XDCP J0044.0-2033 at z=1.58,
the most massive cluster at z >1.5, with a measured mass M200= 4.7x10
Msun. We perform an analysis of the spectral energy distributions (SEDs) of 12
cluster members (5 spectroscopically confirmed) detected with >3
significance in the PACS maps, all ULIRGs. The individual star formation rates
(SFRs) lie in the range 155-824 Ms/yr, with dust temperatures of 2435 K.
We measure a strikingly high amount of star formation (SF) in the cluster core,
SFR ( 1875158 Ms/yr, 4x higher than the amount of star
formation in the cluster outskirts. This scenario is unprecedented in a galaxy
cluster, showing for the first time a reversal of the SF-density relation at
z~1.6 in a massive cluster.Comment: Letter accepted for publication in MNRAS, ESA Press Release on 18
December 201
Discovery of a massive X-ray luminous galaxy cluster at z=1.579
We report on the discovery of a very distant galaxy cluster serendipitously
detected in the archive of the XMM-Newton mission, within the scope of the
XMM-Newton Distant Cluster Project (XDCP). XMMUJ0044.0-2033 was detected at a
high significance level (5sigma) as a compact, but significantly extended
source in the X-ray data, with a soft-band flux f(r<40")=(1.5+-0.3)x10^(-14)
erg/s/cm2. Optical/NIR follow-up observations confirmed the presence of an
overdensity of red galaxies matching the X-ray emission. The cluster was
spectroscopically confirmed to be at z=1.579 using ground-based VLT/FORS2
spectroscopy. The analysis of the I-H colour-magnitude diagram shows a sequence
of red galaxies with a colour range [3.7 < I-H < 4.6] within 1' from the
cluster X-ray emission peak. However, the three spectroscopic members (all with
complex morphology) have significantly bluer colours relative to the observed
red-sequence. In addition, two of the three cluster members have [OII]
emission, indicative of on-going star formation. Using the spectroscopic
redshift we estimated the X-ray bolometric luminosity, Lbol = 5.8x10^44 erg/s,
implying a massive galaxy cluster. This places XMMU J0044.0-2033 at the
forefront of massive distant clusters, closing the gap between lower redshift
systems and recently discovered proto- and low-mass clusters at z >1.6.Comment: letter to appear in A&
A System of ODEs for Representing Trends of CGM Signals
Diabetes Mellitus is a metabolic disorder which may result in severe and
potentially fatal complications if not well-treated and monitored. In this
study, a quantitative analysis of the data collected using CGM (Continuous
Glucose Monitoring) devices from eight subjects with type 2 diabetes in good
metabolic control at the University Polyclinic Agostino Gemelli, Catholic
University of the Sacred Heart, was carried out. In particular, a system of
ordinary differential equations whose state variables are affected by a
sequence of stochastic perturbations was proposed and used to extract more
informative inferences from the patients' data. For this work, Matlab and R
programs were used to find the most appropriate values of the parameters
(according to the Akaike Information Criterion (AIC) and the Bayesian
Information Criterion (BIC)) for each patient. Fitting was carried out by
Particle Swarm Optimization to minimize the ordinary least squares error
between the observed CGM data and the data from the ODE model. Goodness of fit
tests were made in order to assess which probability distribution was best
suitable for representing the waiting times computed from the model parameters.
Finally, both parametric and non-parametric density estimation of the frequency
histograms associated with the variability of the glucose elimination rate from
blood were conducted and their representative parameters assessed from the
data. The results show that the chosen models succeed in capturing most of the
glucose fluctuations for almost every patient
Bone loss in inflammatory Bowel disease: our multicentric study
Patients with inflammatory bowel disease are at increased risk of developing disorder in bone and mineral metabolism The study was aimed to determine if inflammatory bowel disease (IBD) is a risk factor for osteoporosis in 103 adult patients. We included 103 IBD patients, 67 patients with Crohn's disease (CD) and 36 with ulcerative colitis (UC). Bone mineral density was measured by dual-energy X-ray absorptiometry. We used T score to express bone loss (osteopenia: -2.5 SD 2 years) and active disease would be risk factors of bone mineral loss in IBD
The X-ray luminous galaxy cluster XMMU J1007.4+1237 at z=1.56 - The dawn of starburst activity in cluster cores
Observational galaxy cluster studies at z>1.5 probe the formation of the
first massive M>10^14 Msun dark matter halos, the early thermal history of the
hot ICM, and the emergence of the red-sequence population of quenched
early-type galaxies. We present first results for the newly discovered X-ray
luminous galaxy cluster XMMU J1007.4+1237 at z=1.555, detected and confirmed by
the XMM-Newton Distant Cluster Project (XDCP) survey. We selected the system as
a serendipitous weak extended X-ray source in XMM-Newton archival data and
followed it up with two-band near-infrared imaging and deep optical
spectroscopy. We can establish XMMU J1007.4+1237 as a spectroscopically
confirmed, massive, bona fide galaxy cluster with a bolometric X-ray luminosity
of Lx=(2.1+-0.4)\times 10^44 erg/s, a red galaxy population centered on the
X-ray emission, and a central radio-loud brightest cluster galaxy. However, we
see evidence for the first time that the massive end of the galaxy population
and the cluster red-sequence are not yet fully in place. In particular, we find
ongoing starburst activity for the third ranked galaxy close to the center and
another slightly fainter object. At a lookback time of 9.4Gyr, the cluster
galaxy population appears to be caught in an important evolutionary phase,
prior to full star-formation quenching and mass assembly in the core region.
X-ray selection techniques are an efficient means of identifying and probing
the most distant clusters without any prior assumptions about their galaxy
content.Comment: 6 pages, 3 color figures, accepted for publication in A&
A large-scale galaxy structure at z = 2.02 associated with the radio galaxy MRC 0156-252
We present the spectroscopic confirmation of a structure of galaxies surrounding the radio galaxy MRC 0156-252 at z = 2.02. The structure was initially discovered as an overdensity of both near-infrared selected z > 1.6 and mid-infrared selected z > 1.2 galaxy candidates. We used the VLT/FORS2 multi-object spectrograph to target ~80 high-redshift galaxy candidates, and obtain robust spectroscopic redshifts for more than half the targets. The majority of the confirmed sources are star-forming galaxies at z > 1.5. In addition to the radio galaxy, two of its close-by companions (<6″) also show AGN signatures. Ten sources, including the radio galaxy, lie within | z − 2.020 | <0.015 (i.e., velocity offsets <1500 km s^-1) and within projected 2 Mpc comoving of the radio galaxy. Additional evidence suggests not only that the galaxy structure associated with MRC 0156-252 is a forming galaxy cluster but also that this structure is most probably embedded in a larger-scale structure
ExoClock project: an open platform for monitoring the ephemerides of Ariel targets with contributions from the public
The Ariel mission will observe spectroscopically around 1000 exoplanets to further characterise their atmospheres. For the mission to be as efficient as possible, a good knowledge of the planets’ ephemerides is needed before its launch in 2028. While ephemerides for some planets are being refined on a per-case basis, an organised effort to collectively verify or update them when necessary does not exist. In this study, we introduce the ExoClock project, an open, integrated and interactive platform with the purpose of producing a confirmed list of ephemerides for the planets that will be observed by Ariel. The project has been developed in a manner to make the best use of all available resources: observations reported in the literature, observations from space instruments and, mainly, observations from ground-based telescopes, including both professional and amateur observatories. To facilitate inexperienced observers and at the same time achieve homogeneity in the results, we created data collection and validation protocols, educational material and easy to use interfaces, open to everyone. ExoClock was launched in September 2019 and now counts over 140 participants from more than 15 countries around the world. In this release, we report the results of observations obtained until the 15h of April 2020 for 120 Ariel candidate targets. In total, 632 observations were used to either verify or update the ephemerides of 84 planets. Additionally, we developed the Exoplanet Characterisation Catalogue (ECC), a catalogue built in a consistent way to assist the ephemeris refinement process. So far, the collaborative open framework of the ExoClock project has proven to be highly efficient in coordinating scientific efforts involving diverse audiences. Therefore, we believe that it is a paradigm that can be applied in the future for other research purposes, too
- …