The XXL Survey Adami, C.; Giles, P.; Koulouridis, E. ...
Astronomy and astrophysics (Berlin),
12/2018, Volume:
620
Journal Article
Peer reviewed
Open access
Context.
In the currently debated context of using clusters of galaxies as cosmological probes, the need for well-defined cluster samples is critical.
Aims.
The XXL Survey has been specifically ...designed to provide a well characterised sample of some 500 X-ray detected clusters suitable for cosmological studies. The main goal of present article is to make public and describe the properties of the cluster catalogue in its present state, as well as of associated catalogues of more specific objects such as super-clusters and fossil groups.
Methods.
Following from the publication of the hundred brightest XXL clusters, we now release a sample containing 365 clusters in total, down to a flux of a few 10
−15
erg s
−1
cm
−2
in the 0.5–2 keV band and in a 1′ aperture. This release contains the complete subset of clusters for which the selection function is well determined plus all X-ray clusters which are, to date, spectroscopically confirmed. In this paper, we give the details of the follow-up observations and explain the procedure adopted to validate the cluster spectroscopic redshifts. Considering the whole XXL cluster sample, we have provided two types of selection, both complete in a particular sense: one based on flux-morphology criteria, and an alternative based on the 0.5–2 keV flux within 1 arcmin of the cluster centre. We have also provided X-ray temperature measurements for 80% of the clusters having a flux larger than 9 × 10
−15
erg s
−1
cm
−2
.
Results.
Our cluster sample extends from
z
~ 0 to
z
~ 1.2, with one cluster at
z
~ 2. Clusters were identified through a mean number of six spectroscopically confirmed cluster members. The largest number of confirmed spectroscopic members in a cluster is 41. Our updated luminosity function and luminosity–temperature relation are compatible with our previous determinations based on the 100 brightest clusters, but show smaller uncertainties. We also present an enlarged list of super-clusters and a sample of 18 possible fossil groups.
Conclusions.
This intermediate publication is the last before the final release of the complete XXL cluster catalogue when the ongoing C2 cluster spectroscopic follow-up is complete. It provides a unique inventory of medium-mass clusters over a 50 deg
2
area out to
z
~ 1.
We studied the effect of the acute central administration of obestatin on food intake and body weight in short-term starved male rats, and those of 28-day continuous intracerebroventricular (icv) ...infusion of obestatin in free feeding rats. In 16-h starved rats, obestatin induced a trend toward a reduction of food intake that did not reach statistical significance. In fed rats, the icv infusion of obestatin significantly decreased food consumption in the first day of treatment; but the anorexigenic effect of obestatin vanished thereafter. Interestingly, the body weight of rats infused for 28 days with obestatin was superimposable to that of the respective control at all time intervals. In all, our results indicate that the anorexigenic effect of obestatin is of little account and that the peptide does not modify energy metabolism in the long-term administration.
The XXL Survey Pacaud, F; Clerc, N; Giles, P A ...
Astronomy and astrophysics (Berlin),
08/2016, Volume:
592
Journal Article
Peer reviewed
Open access
Context. The XXL Survey is the largest survey carried out by the XMM-Newton satellite and covers a total area of 50 square degrees distributed over two fields. It primarily aims at investigating the ...large-scale structures of the Universe using the distribution of galaxy clusters and active galactic nuclei as tracers of the matter distribution. The survey will ultimately uncover several hundreds of galaxy clusters out to a redshift of ~2 at a sensitivity of ~10 super(-14) ergs super(-1)cm super(-2) in the 0.5-2 keV band. Aims. This article presents the XXL bright cluster sample, a subsample of 100 galaxy clusters selected from the full XXL catalogue by setting a lower limit of 3 x 10 super(-14) erg s super(-1) cm super(-2) on the source flux within a 1? aperture. Methods. The selection function was estimated using a mixture of Monte Carlo simulations and analytical recipes that closely reproduce the source selection process. An extensive spectroscopic follow-up provided redshifts for 97 of the 100 clusters. We derived accurate X-ray parameters for all the sources. Scaling relations were self-consistently derived from the same sample in other publications of the series. On this basis, we study the number density, luminosity function, and spatial distribution of the sample. Results. The bright cluster sample consists of systems with masses between M sub(500)= 7 x 10 super(13) and 3 x 10 super(14)M sub(?), mostly located between z= 0.1 and 0.5. The observed sky density of clusters is slightly below the predictions from the WMAP9 model, and significantly below the prediction from the Planck 2015 cosmology. In general, within the current uncertainties of the cluster mass calibration, models with higher values of sigma sub(8) and/or Omega sub(M) appear more difficult to accommodate. We provide tight constraints on the cluster differential luminosity function and find no hint of evolution out to z~ 1. We also find strong evidence for the presence of large-scale structures in the XXL bright cluster sample and identify five new superclusters.
We present the first results from a galaxy population study in the highest redshift galaxy clusters identified in the 2500 deg
2
South Pole Telescope Sunyaev Zel’dovich effect (SPT-SZ) survey, which ...is sensitive to
M
500
≳ 3 × 10
14
M
⊙
clusters from
z
∼ 0.2 out to the highest redshifts where such massive structures exist. The cluster selection is to first order independent of galaxy properties, making the SPT-SZ sample particularly well suited for cluster galaxy population studies. We carried out a four-band imaging campaign with the
Hubble
and
Spitzer
Space Telescopes of the five
z
≳ 1.4,
S
/
N
SZE
> 5 clusters, that are among the rarest most massive clusters known at this redshift. All five clusters show clear overdensities of red galaxies whose colors agree with the initial cluster redshift estimates, although one (SPT-CLJ0607–4448) shows a galaxy concentration much less prominent than the others. The highest redshift cluster in this sample, SPT-CLJ0459–4947 at
z
∼ 1.72, is the most distant
M
500
> 10
14
M
⊙
cluster discovered thus far through its intracluster medium, and is one of only three known clusters in this mass range at
z
≳ 1.7, regardless of selection. Based on
U
V
J
-like photometric classification of quiescent and star-forming galaxies, we find that the quiescent fraction in the cluster central regions (
r
/
r
500
< 0.7) is higher than in the field at the same redshift, with corresponding environmental quenching efficiencies typically in the range ∼0.5 − 0.8 for stellar masses log(
M
/
M
⊙
) > 10.85. We have explored the impact of emission from star formation on the selection of this sample, concluding that all five clusters studied here would still have been detected with
S
/
N
SZE
> 5, even if they had the same quiescent fraction as measured in the field. Our results thus point towards an efficient suppression of star formation in the central regions of the most massive clusters, occurring already earlier than
z
∼ 1.5.
In the last decades we have come to understand that the hypothalamus is a key region in controlling energy homeostasis. A number of control models have been proposed to explain the regulation of ...feeding behavior in physiological and pathological conditions, but all those based on imbalances of single factors fail to explain the disrupted regulation of energy supply in eating disorders such as anorexia nervosa and bulimia nervosa, as well as other psychiatric disorders. A growing amount of evidence demonstrates that many signaling molecules originated within the brain or coming from the adipose tissue or the gastro-enteric tract are involved in the highly complex process controlling food intake and energy expenditure. The recent discovery of leptin, ghrelin, and other factors have made it possible to penetrate in the still undefined pathophysiology of eating disorders with the hope of finding effective treatments for such diseases.
Ghrelin, the endogenous ligand of the GH secretagogue receptor (GHS‐R) has been previously shown to inhibit gastric acid secretion in pylorus‐ligated rats. Two isoforms of GHS‐R have been identified: ...GHS‐R1a and GHS‐R1b. The present study aimed: (i) to characterise the type of GHS‐R involved in the central gastric inhibitory activity of ghrelin by using des‐octanoyl ghrelin, and synthetic GHS‐R1a agonist (EP1572) and antagonist (D‐Lys3‐GHRP‐6) and (ii) to investigate the relationship between ghrelin and cortistatin (CST) in the control of gastric acid secretion by using the natural neuropeptide CST‐14 and the synthetic octapeptide CST‐8. The specific interactions of all the compounds with GHS‐R1a were determined by comparing their ability to displace labelled ghrelin or somatostatin from its receptors on rat hypothalamic membranes or on rat cardiomyocyte, respectively. Intracerebroventricular administration of 0.01 and 1 nmol/rat des‐octanoyl ghrelin did not affect gastric acid secretion in pylorus‐ligated rats, whereas EP1572 either i.c.v. (0.01–1 nmol/rat) or i.p. (10 and 20 nmol/kg) inhibited acid gastric secretion. Preteatment with D‐Lys3GHRP‐6 (3 nmol/rat, i.c.v.) was able to remove the inhibitory action of ghrelin (0.01 nmol/rat, i.c.v.) on gastric acid volume and acid output, thus indicating that the type 1a GHS‐R likely mediates the gastric inhibitory action of ghrelin. This is supported by binding data showing that D‐Lys3GHRP‐6, but not des‐octanoyl ghrelin, binds to hypothalamic GHS‐R. CST‐14 (1 nmol/rat, i.c.v.) did not affect either basal or ghrelin inhibition of gastric acid secretion. CST‐8 (1 nmol/rat, i.c.v.) was able to counteract the gastric ghrelin response. The observation that CST‐14 binds both GHR‐S and somatostatin receptors, whereas CST‐8 specifically displaces only ghrelin binding, indicates that CST‐8 behaves as a GHS‐R1a antagonist.
Abstract
Ghrelin, the endogenous ligand of the GH secretagogue receptor (GHS‐R) has been previously shown to inhibit gastric acid secretion in pylorus‐ligated rats. Two isoforms of GHS‐R have been ...identified: GHS‐R
1a
and GHS‐R
1b
. The present study aimed: (i) to characterise the type of GHS‐R involved in the central gastric inhibitory activity of ghrelin by using des‐octanoyl ghrelin, and synthetic GHS‐R
1a
agonist (EP1572) and antagonist (D‐Lys
3
‐GHRP‐6) and (ii) to investigate the relationship between ghrelin and cortistatin (CST) in the control of gastric acid secretion by using the natural neuropeptide CST‐14 and the synthetic octapeptide CST‐8. The specific interactions of all the compounds with GHS‐R
1a
were determined by comparing their ability to displace labelled ghrelin or somatostatin from its receptors on rat hypothalamic membranes or on rat cardiomyocyte, respectively. Intracerebroventricular administration of 0.01 and 1 nmol/rat des‐octanoyl ghrelin did not affect gastric acid secretion in pylorus‐ligated rats, whereas EP1572 either i.c.v. (0.01–1 nmol/rat) or i.p. (10 and 20 nmol/kg) inhibited acid gastric secretion. Preteatment with D‐Lys
3
GHRP‐6 (3 nmol/rat, i.c.v.) was able to remove the inhibitory action of ghrelin (0.01 nmol/rat, i.c.v.) on gastric acid volume and acid output, thus indicating that the type 1a GHS‐R likely mediates the gastric inhibitory action of ghrelin. This is supported by binding data showing that D‐Lys
3
GHRP‐6, but not des‐octanoyl ghrelin, binds to hypothalamic GHS‐R. CST‐14 (1 nmol/rat, i.c.v.) did not affect either basal or ghrelin inhibition of gastric acid secretion. CST‐8 (1 nmol/rat, i.c.v.) was able to counteract the gastric ghrelin response. The observation that CST‐14 binds both GHR‐S and somatostatin receptors, whereas CST‐8 specifically displaces only ghrelin binding, indicates that CST‐8 behaves as a GHS‐R
1a
antagonist.
GJ\,581 is a nearby M dwarf known to host a packed multiple planet system composed of two super-Earths and a Neptune-mass planet. We present new orbital analyses of the GJ\,581 system, utilizing ...recent radial velocity (RV) data obtained from the CARMENES spectrograph combined with newly reprocessed archival data from the HARPS and HIRES spectrographs. Our aim was to analyze the post-discovery spectroscopic data of GJ\,581, which were obtained with CARMENES. In addition, we used publicly available HIRES and HARPS spectroscopic data to seek evidence of the known and disputed exoplanets in this system. We aimed to investigate the stellar activity of GJ\,581 and update the planetary system's orbital parameters using state-of-the-art numerical models and techniques. We performed a periodogram analysis of the available precise CARMENES, HIRES, and HARPS RVs and of stellar activity indicators. We conducted detailed orbital analyses by testing various orbital configurations consistent with the RV data. We studied the posterior probability distribution of the parameters fit to the data and we explored the long-term stability and overall orbital dynamics of the GJ\,581 system. We refined the orbital parameters of the GJ\,581 system using the most precise and complete set of Doppler data available. Consistent with the existing literature, our analysis confirms that the system is unequivocally composed of only three planets detectable in the present data, dismissing the putative planet GJ\,581\,d as an artifact of stellar activity. Our N-body fit reveals that the system's inclination is $i = $\,deg, which implies that the planets could be up to 30<!PCT!> more massive than their previously reported minimum masses. Furthermore, we report that the GJ\,581 system exhibits long-term stability, as indicated by the posterior probability distribution, characterized by secular dynamical interactions without the involvement of mean motion resonances.
The XXL Survey Farahi, Arya; Guglielmo, Valentina; Evrard, August E. ...
Astronomy and astrophysics (Berlin),
12/2018, Volume:
620
Journal Article
Peer reviewed
Open access
Context.
An X-ray survey with the
XMM-Newton
telescope, XMM-XXL, has identified hundreds of galaxy groups and clusters in two 25 deg
2
fields. Combining spectroscopic and X-ray observations in one ...field, we determine how the kinetic energy of galaxies scales with hot gas temperature and also, by imposing prior constraints on the relative energies of galaxies and dark matter, infer a power-law scaling of total mass with temperature.
Aims.
Our goals are: i) to determine parameters of the scaling between galaxy velocity dispersion and X-ray temperature,
T
300 kpc
, for the halos hosting XXL-selected clusters, and; ii) to infer the log-mean scaling of total halo mass with temperature, ⟨ln
M
200
|
T
300 kpc
,
z
⟩.
Methods.
We applied an ensemble velocity likelihood to a sample of >1500 spectroscopic redshifts within 132 spectroscopically confirmed clusters with redshifts
z
< 0.6 to model, ⟨ln
σ
gal
|
T
300 kpc
,
z
⟩, where
σ
gal
is the velocity dispersion of XXL cluster member galaxies and
T
300 kpc
is a 300 kpc aperture temperature. To infer total halo mass we used a precise virial relation for massive halos calibrated by
N
-body simulations along with a single degree of freedom summarising galaxy velocity bias with respect to dark matter.
Results.
For the XXL-N cluster sample, we find σ
gal
∝ T
300 kpc
0.63±0.05
, a slope significantly steeper than the self-similar expectation of 0.5. Assuming scale-independent galaxy velocity bias, we infer a mean logarithmic mass at a given X-ray temperature and redshift,
〈ln(
E
(
z
)
M
200
/10
14
M
⊙
)|T
300
kpc,
z
〉 = π
T
+ α
T
ln (
T
300
kpc/
T
p
) +
β
T
ln (
E
(
z
)/
E
(
z
p
)) using pivot values
kT
p
= 2.2 keV and
z
p
= 0.25, with normalization
π
T
= 0.45 ± 0.24 and slope
α
T
= 1.89 ± 0.15. We obtain only weak constraints on redshift evolution,
β
T
= −1.29 ± 1.14.
Conclusions.
The ratio of specific energies in hot gas and galaxies is scale dependent. Ensemble spectroscopic analysis is a viable method to infer mean scaling relations, particularly for the numerous low mass systems with small numbers of spectroscopic members per system. Galaxy velocity bias is the dominant systematic uncertainty in dynamical mass estimates.
This study was designed to evaluate whether or not continuous intracerebroventricular infusion of leptin (1.5
μg/rat/24
h, for 28 days) produced different regional response on the skeleton of growing ...rats. Leptin reduce the accretion of total femoral bone mineral content (BMC) and density (BMD). This effect was related to a reduction of metaphyseal femur as no changes were detected in the diaphysis. Despite the reduced accretion in the volumetric of both femur and tibia compared to controls, leptin had no significant effects on the lumbar vertebrae. Urine deoxypyrydinoline and serum osteocalcin remained more elevated in the leptin-treated group as compared to controls. The results demonstrate that long-term central infusion of leptin activates bone remodeling with a negative balance. Leptin induces distinct responses in the different structure of bone and in the axial and appendicular skeleton.
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