Abstract
The possibly unbiased selection process in surveys of the Sunyaev Zel'dovich effect can unveil new populations of galaxy clusters. We performed a weak lensing analysis of the PSZ2LenS ...sample, i.e. the PSZ2 galaxy clusters detected by the Planck mission in the sky portion covered by the lensing surveys CFHTLenS and RCSLenS. PSZ2LenS consists of 35 clusters and it is a statistically complete and homogeneous subsample of the PSZ2 catalogue. The Planck selected clusters appear to be unbiased tracers of the massive end of the cosmological haloes. The mass–concentration relation of the sample is in excellent agreement with predictions from the Λ cold dark matter model. The stacked lensing signal is detected at 14σ significance over the radial range 0.1 < R < 3.2 Mpc h−1, and is well described by the cuspy dark halo models predicted by numerical simulations. We confirmed that Planck estimated masses are biased low by bSZ = 27 ± 11(stat) ± 8(sys) per cent with respect to weak lensing masses. The bias is higher for the cosmological subsample, bSZ = 40 ± 14(stat) ± 8(sys) per cent.
Mass and concentration of clusters of galaxies are related and evolving with redshift. We study the properties of a sample of 31 massive galaxy clusters at high redshift, 0.8 z 1.5, using weak and ...strong lensing observations. Concentration is a steep function of mass, c
200 ∝ M200
−0.83 ± 0.39, with higher redshift clusters being less concentrated. Mass and concentration from the stacked analysis, M
200 = (4.1 ± 0.4) × 1014 M h
−1 and c
200 = 2.3 ± 0.2, are in line with theoretical results extrapolated from the local Universe. Clusters with signs of dynamical activity preferentially feature high concentrations. We discuss the possibility that the whole sample is a mix of two different kinds of haloes. Overconcentrated clusters might be accreting haloes out of equilibrium in a transient phase of compression, whereas less concentrated ones might be more relaxed.
We present observational evidence of the two-halo term in the stacked shear profile of a sample of ~1200 optically selected galaxy clusters based on imaging data and the public shear catalog from the ...CFHTLenS. We find that the halo bias, a measure of the correlated distribution of matter around galaxy clusters, has amplitude and correlation with galaxy cluster mass in very good agreement with the predictions based on the LCDM standard cosmological model. The mass-concentration relation is flat but higher than theoretical predictions. We also confirm the close scaling relation between the optical richness of galaxy clusters and their mass.
The joint analysis of clustering and stacked gravitational lensing of galaxy clusters in large surveys can constrain the formation and evolution of structures and the cosmological parameters. On ...scales outside a few virial radii, the halo bias, b, is linear and the lensing signal is dominated by the correlated distribution of matter around galaxy clusters. We discuss a method to measure the power spectrum amplitude σ8 and b based on a minimal modelling. We considered a sample of ∼120 000 clusters photometrically selected from the Sloan Digital Sky Survey in the redshift range 0.1 < z < 0.6. The autocorrelation was studied through the two-point function of a subsample of ∼70 000 clusters; the matter–halo correlation was derived from the weak lensing signal of the subsample of ∼1200 clusters with Canada–France–Hawaii Telescope Lensing Survey data. We obtained a direct measurement of b, which increases with mass in agreement with predictions of the Λ cold dark matter paradigm. Assuming ΩM = 0.3, we found σ8 = 0.79 ± 0.16. We used the same clusters for measuring both lensing and clustering and the estimate of σ8 did require neither the mass–richness relation, nor the knowledge of the selection function, nor the modelling of b. With an additional theoretical prior on the bias, we obtained σ8 = 0.75 ± 0.08.
ABSTRACT Based on weak lensing data from the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS), in this paper we study the mass-concentration (M-c) relation for ∼200 redMaPPer clusters in the ...fields. We extract the M-c relation by measuring the density profiles of individual clusters instead of using stacked weak lensing signals. By performing Monte Carlo simulations, we demonstrate that although the signal-to-noise ratio for each individual cluster is low, the unbiased M-c relation can still be reliably derived from a large sample of clusters by carefully taking into account the impacts of shape noise, cluster center offset, dilution effect from member or foreground galaxies, and the projection effect. Our results show that within error bars the derived M-c relation for redMaPPer clusters is in agreement with simulation predictions. There is a weak deviation in that the halo concentrations calibrated by Monte Carlo simulations are somewhat higher than that predicted from Planck cosmology.
Understanding the mechanisms that lead dense environments to host galaxies with redder colors, more spheroidal morphologies, and lower star formation rates than field populations remains an important ...problem. As most candidate processes ultimately depend on host halo mass, accurate characterizations of the local environment, ideally tied to halo mass estimates and spanning a range in halo mass and redshift, are needed. In this work, we present and test a rigorous, probabilistic method for assigning galaxies to groups based on precise photometric redshifts and X-ray-selected groups drawn from the COSMOS field. The groups have masses in the range 1013 M 200c/M 1014 and span redshifts 0 < z < 1. We characterize our selection algorithm via tests on spectroscopic subsamples, including new data obtained at the Very Large Telescope, and by applying our method to detailed mock catalogs. We find that our group member galaxy sample has a purity of 84% and completeness of 92% within . We measure the impact of uncertainties in redshifts and group centering on the quality of the member selection with simulations based on current data as well as future imaging and spectroscopic surveys. As a first application of our new group member catalog which will be made publicly available, we show that member galaxies exhibit a higher quenched fraction compared to the field at fixed stellar mass out to z ~ 1, indicating a significant relationship between star formation and environment at group scales. We also address the suggestion that dusty star-forming galaxies in such groups may impact the high-l power spectrum of the cosmic microwave background and find that such a population cannot explain the low power seen in recent Sunyaev-Zel'dovich measurements.
The space race is entering a new era of exploration, in which the number of robotic and human missions to various places in our solar system is rapidly increasing. Despite the recent advances in ...propulsion and life support technologies, there is a growing need to perform analytical measurements and laboratory experiments across diverse domains of science, while keeping low payload requirements. In this context, lab-on-a-chip nanobiosensors appear to be an emerging technology capable of revolutionizing space exploration, given their low footprint, high accuracy, and low payload requirements. To date, only some approaches for monitoring astronaut health in spacecraft environments have been reported. Although non-invasive molecular diagnostics, like lab-on-a-chip technology, are expected to improve the quality of long-term space missions, their application to monitor microbiological and environmental variables is rarely reported, even for analogous extreme environments on Earth. The possibility of evaluating the occurrence of unknown or unexpected species, identifying redox gradients relevant to microbial metabolism, or testing for specific possible biosignatures, will play a key role in the future of space microbiology. In this review, we will examine the current and potential roles of lab-on-a-chip technology in space exploration and in extreme environment investigation, reporting what has been tested so far, and clarifying the direction toward which the newly developed technologies of portable lab-on-a-chip sensors are heading for exploration in extreme environments and in space.
Lensing cosmic drift Covone, Giovanni; Sereno, Mauro
Monthly notices of the Royal Astronomical Society,
07/2022, Letnik:
513, Številka:
4
Journal Article
Recenzirano
Odprti dostop
ABSTRACT
As the Universe expands, the redshift of distant sources changes with time. Here, we discuss gravitational lensing phenomena that are consequence of the redshift drift between lensed source, ...gravitational lens, and observer. When the source is located very close to the drifting caustics, a pair of images could occur (or disappear) because of the cosmological expansion. Furthermore, lensing systems act as signal converters of the redshift drift. The angular position, magnification, distortion, and time delay of already existing multiple images change. We estimate the expected frequency of these phenomena and the prospects to observe them in the era of deep and large surveys. The drift detection in image separation could be within reach of next-generation surveys with μarcsec angular resolution.
Abstract
Young terrestrial worlds are critical test beds to constrain prevailing theories of planetary formation and evolution. We present the discovery of HD 63433 d—a nearby (22 pc), Earth-sized ...planet transiting a young Sun-like star (TOI-1726, HD 63433). HD 63433 d is the third planet detected in this multiplanet system. The kinematic, rotational, and abundance properties of the host star indicate that it belongs to the young (414 ± 23 Myr) Ursa Major moving group, whose membership we update using new data from the third data release of the Gaia mission and TESS. Our transit analysis of the TESS light curves indicates that HD 63433 d has a radius of 1.1
R
⊕
and closely orbits its host star with a period of 4.2 days. To date, HD 63433 d is the smallest confirmed exoplanet with an age less than 500 Myr, and the nearest young Earth-sized planet. Furthermore, the apparent brightness of the stellar host (
V
≃ 6.9 mag) makes this transiting multiplanet system favorable to further investigations, including spectroscopic follow-up to probe the atmospheric loss in a young Earth-sized world.
In Cosmology and in Fundamental Physics there is a crucial question like: where the elusive substance that we call Dark Matter is hidden in the Universe and what is it made of? that, even after ...40 years from the Vera Rubin seminal discovery
1
does not have a proper answer. Actually, the more we have investigated, the more this issue has become strongly entangled with aspects that go beyond the established Quantum Physics, the Standard Model of Elementary particles and the General Relativity and related to processes like the Inflation, the accelerated expansion of the Universe and High Energy Phenomena around compact objects. Even Quantum Gravity and very exotic Dark Matter particle candidates may play a role in framing the Dark Matter mystery that seems to be accomplice of new unknown Physics. Observations and experiments have clearly indicated that the above phenomenon cannot be considered as already theoretically framed, as hoped for decades. The Special Topic to which this review belongs wants to penetrate this newly realized mystery from different angles, including that of a contamination of different fields of Physics apparently unrelated. We show with the works of this ST that this contamination is able to guide us into the required new Physics. This review wants to provide a good number of these “paths or contamination” beyond/among the three worlds above; in most of the cases, the results presented here open a direct link with the multi-scale dark matter phenomenon, enlightening some of its important aspects. Also in the remaining cases, possible interesting contacts emerges. Finally, a very complete and accurate bibliography is provided to help the reader in navigating all these issues.
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