The galaxy phase-space distribution in galaxy clusters provides insights into the formation and evolution of cluster galaxies, and it can also be used to measure cluster mass profiles. We present a ...dynamical study based on $\sim$3000 passive, non-emission line cluster galaxies drawn from 110 galaxy clusters. The galaxy clusters were selected using the Sunyaev-Zel'dovich effect (SZE) in the 2500~deg$^2$ SPT-SZ survey and cover the redshift range $0.2 < z < 1.3$. We model the clusters using the Jeans equation, while adopting NFW mass profiles and a broad range of velocity dispersion anisotropy profiles. The data prefer velocity dispersion anisotropy profiles that are approximately isotropic near the center and increasingly radial toward the cluster virial radius, and this is true for all redshifts and masses we study. The pseudo-phase-space density profile of the passive galaxies is consistent with expectations for dark matter particles and subhalos from cosmological $N$-body simulations. The dynamical mass constraints are in good agreement with external mass estimates of the SPT cluster sample from either weak lensing, velocity dispersions, or X-ray $Y_X$ measurements. However, the dynamical masses are lower (at the 2.2$\sigma$ level) when compared to the mass calibration favored when fitting the SPT cluster data to a $\Lambda$CDM model with external cosmological priors, including CMB anisotropy data from Planck. The discrepancy grows with redshift, where in the highest redshift bin the ratio of dynamical to SPT+Planck masses is $\eta=0.63^{+0.13}_{-0.08}\pm0.06$ (statistical and systematic), corresponding to a $2.6\sigma$ discrepancy.
Energy homeostasis is controlled by a complex regulatory system of molecules that affect food intake and that are critical for maintaining a stable body weight during life. Ghrelin is a peptide of 28 ...amino acid synthesized predominantly by the stomach and the gut, which activate the type 1a growth hormone (GH) secretagogue receptor (GHS-R1a), a G-protein coupled receptor. The acylated form of ghrelin potently stimulates GH secretion both in vitro and in vivo in several animal species, including humans. Beside the endocrine effect, ghrelin shows also extraendocrine activities, including stimulation of feeding behaviour. Several classes of small synthetic peptide and non-peptide ligands of the GHS-R1a have been described and are able to release GH and stimulate food intake. However, in time, it appeared that the stimulating effects on GH secretion could be divorced from those on food intake, suggesting that more than a single receptor might be involved. Several experimental data have even questioned the physiological role of ghrelin in the control of GH secretion and energy metabolism. By using novel agonists, partial agonists, and antagonists for the GHS-R1a receptor, we have studied whether the stimulation of this receptor could account for the purported physiological role of ghrelin. Our results demonstrate that the ability to bind in vitro the GHS-R1a is not predictive of the in vivo biological activity of the compounds and that the endocrine and extraendocrine effects could be mediated also by receptors different from the GHS-R1a.
We present a detection of the splashback feature around galaxy clusters selected using the Sunyaev-Zel'dovich (SZ) signal. Recent measurements of the splashback feature around optically selected ...galaxy clusters have found that the splashback radius, rsp, is smaller than predicted by N-body simulations. A possible explanation for this discrepancy is that rsp inferred from the observed radial distribution of galaxies is affected by selection effects related to the optical cluster-finding algorithms. We test this possibility by measuring the splashback feature in clusters selected via the SZ effect in data from the South Pole Telescope SZ survey and the Atacama Cosmology Telescope Polarimeter survey. The measurement is accomplished by correlating these cluster samples with galaxies detected in the Dark Energy Survey Year 3 data. The SZ observable used to select clusters in this analysis is expected to have a tighter correlation with halo mass and to be more immune to projection effects and aperture-induced biases, potentially ameliorating causes of systematic error for optically selected clusters. We find that the measured rsp for SZ-selected clusters is consistent with the expectations from simulations, although the small number of SZ-selected clusters makes a precise comparison difficult. In agreement with previous work, when using optically selected redMaPPer clusters with similar mass and redshift distributions, rsp is ~2σ smaller than in the simulations. These results motivate detailed investigations of selection biases in optically selected cluster catalogues and exploration of the splashback feature around larger samples of SZ-selected clusters. Additionally, we investigate trends in the galaxy profile and splashback feature as a function of galaxy colour, finding that blue galaxies have profiles close to a power law with no discernible splashback feature, which is consistent with them being on their first infall into the cluster.
We present a detection of the splashback feature around galaxy clusters selected using their Sunyaev-Zel'dovich (SZ) signal. Recent measurements of the splashback feature around optically selected ...galaxy clusters have found that the splashback radius, $r_{\rm sp}$, is smaller than predicted by N-body simulations. A possible explanation for this discrepancy is that $r_{\rm sp}$ inferred from the observed radial distribution of galaxies is affected by selection effects related to the optical cluster-finding algorithms. We test this possibility by measuring the splashback feature in clusters selected via the SZ effect in data from the South Pole Telescope SZ survey and the Atacama Cosmology Telescope Polarimeter survey. The measurement is accomplished by correlating these clusters with galaxies detected in the Dark Energy Survey Year 3 data. The SZ observable used to select clusters in this analysis is expected to have a tighter correlation with halo mass and to be more immune to projection effects and aperture-induced biases than optically selected clusters. We find that the measured $r_{\rm sp}$ for SZ-selected clusters is consistent with the expectations from simulations, although the small number of SZ-selected clusters makes a precise comparison difficult. In agreement with previous work, when using optically selected redMaPPer clusters, $r_{\rm sp}$ is $\sim$ $2\sigma$ smaller than in the simulations. These results motivate detailed investigations of selection biases in optically selected cluster catalogs and exploration of the splashback feature around larger samples of SZ-selected clusters. Additionally, we investigate trends in the galaxy profile and splashback feature as a function of galaxy color, finding that blue galaxies have profiles close to a power law with no discernible splashback feature, which is consistent with them being on their first infall into the cluster.
Abstract
We derive cosmological constraints using a galaxy cluster sample selected from the 2500 deg
2
SPT-SZ survey. The sample spans the redshift range 0.25 <
z
< 1.75 and contains 343 clusters ...with SZ detection significance
ξ
> 5. The sample is supplemented with optical weak gravitational lensing measurements of 32 clusters with 0.29 <
z
< 1.13 (from Magellan and
Hubble Space Telescope
) and X-ray measurements of 89 clusters with 0.25 <
z
< 1.75 (from
Chandra
). We rely on minimal modeling assumptions: (i) weak lensing provides an accurate means of measuring halo masses, (ii) the mean SZ and X-ray observables are related to the true halo mass through power-law relations in mass and dimensionless Hubble parameter
E
(
z
) with a priori unknown parameters, and (iii) there is (correlated, lognormal) intrinsic scatter and measurement noise relating these observables to their mean relations. We simultaneously fit for these astrophysical modeling parameters and for cosmology. Assuming a flat
ν
ΛCDM model, in which the sum of neutrino masses is a free parameter, we measure Ω
m
= 0.276 ± 0.047,
σ
8
= 0.781 ± 0.037, and
σ
8
(Ω
m
/0.3)
0.2
= 0.766 ±0.025. The redshift evolutions of the X-ray
Y
X
–mass and
M
gas
–mass relations are both consistent with self-similar evolution to within 1
σ
. The mass slope of the
Y
X
–mass relation shows a 2.3
σ
deviation from self-similarity. Similarly, the mass slope of the
M
gas
–mass relation is steeper than self-similarity at the 2.5
σ
level. In a
νw
CDM cosmology, we measure the dark energy equation-of-state parameter
w
= −1.55 ± 0.41 from the cluster data. We perform a measurement of the growth of structure since redshift
z
∼ 1.7 and find no evidence for tension with the prediction from general relativity. This is the first analysis of the SPT cluster sample that uses direct weak-lensing mass calibration and is a step toward using the much larger weak-lensing data set from DES. We provide updated redshift and mass estimates for the SPT sample.
Here, we present weak lensing (WL) mass constraints for a sample of massive galaxy clusters detected by the South Pole Telescope (SPT) via the Sunyaev-Zel'dovich effect (SZE). We use griz imaging ...data obtained from the Science Verification (SV) phase of the Dark Energy Survey (DES) to fit the WL shear signal of 33 clusters in the redshift range 0.25 ≤ z ≤ 0.8 with NFW profiles and to constrain a four-parameter SPT mass-observable relation. To account for biases in WL masses, we introduce a WL mass to true mass scaling relation described by a mean bias and an intrinsic, log-normal scatter. We allow for correlated scatter within the WL and SZE mass-observable relations and use simulations to constrain priors on nuisance parameters related to bias and scatter from WL. We constrain the normalization of the $\zeta$-M500 relation, $\mathrm{A_{SZ}}$ = 12.0$+2.6\atop{-6.7}$ when using a prior on the mass slope $B_\mathrm{SZ}$ from the latest SPT cluster cosmology analysis. Without this prior, we recover $A_\mathrm{SZ}=10.8_{-5.2}^{+2.3}$ and $B_\mathrm{SZ}=1.30_{-0.44}^{+0.22}$. Results in both cases imply lower cluster masses than measured in previous work with and without WL, although the uncertainties are large. The WL derived value of $B_\mathrm{SZ}$ is $\approx 20\%$ lower than the value preferred by the most recent SPT cluster cosmology analysis. The method shown in this work is designed to constrain cluster masses and cosmological parameters simultaneously and will form the basis for subsequent studies that employ the full SPT cluster sample together with the DES data.
Central administration of amylin (2.2 μg/rat, i.c.v.) reduces (from a minimum of 67% to 83%) indomethacin (Indo, 20 mg Kg
−1, orally) induced ulcers in rats. The anti-ulcer effect of the peptide is ...not removed by the administration of prokinetic drugs like domperidone or neostigmine but it is reduced by 35% in rats treated with capsaicin or with the CGRP antagonist, CGRP
8–37. These data indicate that amylin gastroprotection involves capsaicin-sensitive nerve fiber leading to CGRP-dependent gastric vasodilatory effect. Additional mechanisms could involve noradrenergic α
2 receptors as the peptide gastroprotective activity is reduced from 67% to 20% by the α
2 antagonist yohimbine.
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