scholarly journals The XXL Survey

2018 ◽  
Vol 620 ◽  
pp. A10 ◽  
Author(s):  
F. Pacaud ◽  
M. Pierre ◽  
J.-B. Melin ◽  
C. Adami ◽  
A. E. Evrard ◽  
...  
Keyword(s):  
Cold Dark Matter ◽  
Signal To Noise Ratio ◽  
Cosmological Parameters ◽  
Scaling Relations ◽  
High Signal ◽  
Selection Function ◽  
Redshift Distribution ◽  
Self Consistent ◽  
Consistent Manner ◽  
Current Mass

Context. We present an estimation of cosmological parameters with clusters of galaxies. Aims. We constrain the Ωm, σ8, and w parameters from a stand-alone sample of X-ray clusters detected in the 50 deg2 XMM-XXL survey with a well-defined selection function. Methods. We analyse the redshift distribution of a sample comprising 178 high signal-to-noise ratio clusters out to a redshift of unity. The cluster sample scaling relations are determined in a self-consistent manner. Results. In a lambda cold dark matter (ΛCDM) model, the cosmology favoured by the XXL clusters compares well with results derived from the Planck Sunyaev-Zel’dovich clusters for a totally different sample (mass/redshift range, selection biases, and scaling relations). However, with this preliminary sample and current mass calibration uncertainty, we find no inconsistency with the Planck CMB cosmology. If we relax the w parameter, the Planck CMB uncertainties increase by a factor of ~10 and become comparable with those from XXL clusters. Combining the two probes allows us to put constraints on Ωm = 0.316 ± 0.060, σ8 = 0.814 ± 0.054, and w = −1.02 ± 0.20. Conclusions. This first self-consistent cosmological analysis of a sample of serendipitous XMM clusters already provides interesting insights into the constraining power of the XXL survey. Subsequent analysis will use a larger sample extending to lower confidence detections and include additional observable information, potentially improving posterior uncertainties by roughly a factor of 3.

scholarly journals Hemispherical variance anomaly and reionization optical depth

2020 ◽  
Vol 499 (3) ◽  
pp. 3563-3570
Author(s):  
Márcio O’Dwyer ◽  
Craig J Copi ◽  
Johanna M Nagy ◽  
C Barth Netterfield ◽  
John Ruhl ◽  
...  
Keyword(s):  
Optical Depth ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Signal To Noise Ratio ◽  
Cosmological Parameters ◽  
Temperature Data ◽  
Microwave Background ◽  
Parameter Uncertainties ◽  
Polarization Data ◽  
Best Fitting

ABSTRACT Cosmic microwave background (CMB) full-sky temperature data show a hemispherical asymmetry in power nearly aligned with the Ecliptic, with the Northern hemisphere displaying an anomalously low variance, while the Southern hemisphere appears consistent with expectations from the best-fitting theory, Lambda Cold Dark Matter (ΛCDM). The low signal-to-noise ratio in current polarization data prevents a similar comparison. Polarization realizations constrained by temperature data show that in ΛCDM the lack of variance is not expected to be present in polarization data. Therefore, a natural way of testing whether the temperature result is a fluke is to measure the variance of CMB polarization components. In anticipation of future CMB experiments that will allow for high-precision large-scale polarization measurements, we study how the variance of polarization depends on ΛCDM-parameter uncertainties by forecasting polarization maps with Planck’s Markov chain Monte Carlo chains. We show that polarization variance is sensitive to present uncertainties in cosmological parameters, mainly due to current poor constraints on the reionization optical depth τ, which drives variance at low multipoles. We demonstrate how the improvement in the τ measurement seen between Planck’s two latest data releases results in a tighter constraint on polarization variance expectations. Finally, we consider even smaller uncertainties on τ and how more precise measurements of τ can drive the expectation for polarization variance in a hemisphere close to that of the cosmic-variance-limited distribution.

scholarly journals Self-consistent redshift estimation using correlation functions without a spectroscopic reference sample

2019 ◽  
Vol 485 (3) ◽  
pp. 3642-3660 ◽  
Author(s):  
Ben Hoyle ◽  
Markus Michael Rau
Keyword(s):  
Dark Matter ◽  
Correlation Functions ◽  
Reference Sample ◽  
Data Driven ◽  
Model Parameters ◽  
Redshift Distribution ◽  
Self Consistent ◽  
The Galaxy ◽  
Consistent Manner ◽  
Order Of Magnitude

ABSTRACT We present a new method to estimate redshift distributions and galaxy-dark matter bias parameters using correlation functions in a fully data driven and self-consistent manner. Unlike other machine learning, template, or correlation redshift methods, this approach does not require a reference sample with known redshifts. By measuring the projected cross- and auto-correlations of different galaxy sub-samples, e.g. as chosen by simple cells in colour–magnitude space, we are able to estimate the galaxy-dark matter bias model parameters, and the shape of the redshift distributions of each sub-sample. This method fully marginalizes over a flexible parametrization of the redshift distribution and galaxy-dark matter bias parameters of sub-samples of galaxies, and thus provides a general Bayesian framework to incorporate redshift uncertainty into the cosmological analysis in a data-driven, consistent, and reproducible manner. This result is improved by an order of magnitude by including cross-correlations with the cosmic microwave background and with galaxy–galaxy lensing. We showcase how this method could be applied to real galaxies. By using idealized data vectors, in which all galaxy-dark matter model parameters and redshift distributions are known, this method is demonstrated to recover unbiased estimates on important quantities, such as the offset Δz between the mean of the true and estimated redshift distribution and the 68 per cent, 95 per cent, and 99.5 per cent widths of the redshift distribution to an accuracy required by current and future surveys.

scholarly journals Detection of Anisotropy in the Cosmic Microwave Background at Horizon and Sub-Horizon Scales with the BOOMERanG Experiment

2005 ◽  
Vol 201 ◽  
pp. 55-64
Author(s):  
P. de Bernardis ◽  
P. A. R. Ade ◽  
J. J. Bock ◽  
J. R. Bond ◽  
J. Borrill ◽  
...  
Keyword(s):  
Total Mass ◽  
Signal To Noise Ratio ◽  
Cosmological Parameters ◽  
Power Spectra ◽  
High Signal ◽  
Mass Energy ◽  
Microwave Background ◽  
Technical Advances ◽  
The Universe

BOOMERanG has recently resolved structures on the last scattering surface at redshift ˜ 1100 with high signal to noise ratio. We review the technical advances which made this possible, and we focus on the current results for maps and power spectra, with special attention to the determination of the total mass-energy density in the Universe and of other cosmological parameters.

scholarly journals The VANDELS ESO public spectroscopic survey: Observations and first data release

2018 ◽  
Vol 616 ◽  
pp. A174 ◽  
Author(s):  
L. Pentericci ◽  
R. J. McLure ◽  
B. Garilli ◽  
O. Cucciati ◽  
P. Franzetti ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
Spectroscopic Data ◽  
Signal To Noise Ratio ◽  
High Redshift ◽  
Measurement Procedure ◽  
Integration Time ◽  
High Signal ◽  
Redshift Distribution ◽  
Data Set ◽  
Data Release

This paper describes the observations and the first data release (DR1) of the ESO public spectroscopic survey “VANDELS, a deep VIMOS survey of the CANDELS CDFS and UDS fields”. The main targets of VANDELS are star-forming galaxies at redshift 2.4 < z < 5.5, an epoch when the Universe had not yet reached 20% of its current age, and massive passive galaxies in the range 1 < z < 2.5. By adopting a strategy of ultra-long exposure times, ranging from a minimum of 20 h to a maximum of 80 h per source, VANDELS is specifically designed to be the deepest-ever spectroscopic survey of the high-redshift Universe. Exploiting the red sensitivity of the refurbished VIMOS spectrograph, the survey is obtaining ultra-deep optical spectroscopy covering the wavelength range 4800–10 000 Å with a sufficiently high signal-to-noise ratio to investigate the astrophysics of high-redshift galaxy evolution via detailed absorption line studies of well-defined samples of high-redshift galaxies. VANDELS-DR1 is the release of all medium-resolution spectroscopic data obtained during the first season of observations, on a 0.2 square degree area centered around the CANDELS-CDFS (Chandra deep-field south) and CANDELS-UDS (ultra-deep survey) areas. It includes data for all galaxies for which the total (or half of the total) scheduled integration time was completed. The DR1 contains 879 individual objects, approximately half in each of the two fields, that have a measured redshift, with the highest reliable redshifts reaching zspec ~ 6. In DR1 we include fully wavelength-calibrated and flux-calibrated 1D spectra, the associated error spectrum and sky spectrum, and the associated wavelength-calibrated 2D spectra. We also provide a catalog with the essential galaxy parameters, including spectroscopic redshifts and redshift quality flags measured by the collaboration. We present the survey layout and observations, the data reduction and redshift measurement procedure, and the general properties of the VANDELS-DR1 sample. In particular, we discuss the spectroscopic redshift distribution and the accuracy of the photometricredshifts for each individual target category, and we provide some examples of data products for the various target typesand the different quality flags. All VANDELS-DR1 data are publicly available and can be retrieved from the ESO archive. Two further data releases are foreseen in the next two years, and a final data release is currently scheduled for June 2020, which will include an improved rereduction of the entire spectroscopic data set.

scholarly journals Methods for cluster cosmology and application to the SDSS in preparation for DES Year 1 release

2019 ◽  
Vol 488 (4) ◽  
pp. 4779-4800 ◽  
Author(s):  
M Costanzi ◽  
E Rozo ◽  
M Simet ◽  
Y Zhang ◽  
A E Evrard ◽  
...  
Keyword(s):  
Cold Dark Matter ◽  
Cosmological Parameters ◽  
Acoustic Oscillation ◽  
Big Bang ◽  
Sloan Digital Sky Survey ◽  
Selection Function ◽  
Mass Relation ◽  
Data Set ◽  
Dark Energy Survey ◽  
Future Work

ABSTRACT We implement the first blind analysis of cluster abundance data to derive cosmological constraints from the abundance and weak lensing signal of redMaPPer clusters in the Sloan Digital Sky Survey (SDSS). We simultaneously fit for cosmological parameters and the richness–mass relation of the clusters. For a flat Λ cold dark matter cosmological model with massive neutrinos, we find $S_8 \equiv \sigma _{8}(\Omega _\mathrm{ m}/0.3)^{0.5}=0.79^{+0.05}_{-0.04}$. This value is both consistent and competitive with that derived from cluster catalogues selected in different wavelengths. Our result is also consistent with the combined probes analyses by the Dark Energy Survey (DES), the Kilo-Degree Survey (KiDS), and with the cosmic microwave background (CMB) anisotropies as measured by Planck. We demonstrate that the cosmological posteriors are robust against variation of the richness–mass relation model and to systematics associated with the calibration of the selection function. In combination with baryon acoustic oscillation data and big bang nucleosynthesis data (Cooke et al.), we constrain the Hubble rate to be h = 0.66 ± 0.02, independent of the CMB. Future work aimed at improving our understanding of the scatter of the richness–mass relation has the potential to significantly improve the precision of our cosmological posteriors. The methods described in this work were developed for use in the forthcoming analysis of cluster abundances in the DES. Our SDSS analysis constitutes the first part of a staged-unblinding analysis of the full DES data set.

scholarly journals Evolution of the MBH–σ and MBH–Lbulge Relations

2009 ◽  
Vol 5 (S267) ◽  
pp. 183-188
Author(s):  
J.-H. Woo ◽  
N. V. Bennert ◽  
T. Treu ◽  
M. Malkan ◽  
R. Blandford
Keyword(s):  
Black Hole ◽  
Velocity Dispersion ◽  
Signal To Noise Ratio ◽  
Decomposition Analysis ◽  
Scaling Relations ◽  
High Signal ◽  
The Past ◽  
Black Hole Growth ◽  
Stellar Velocity ◽  
Galaxy Assembly

AbstractTo constrain the origin of scaling relations between black hole mass and galaxy properties, i.e., stellar velocity dispersion and bulge luminosity, we investigate the evolution of scaling relations in the past 6 Gyrs. Over the last three years, we have obtained high signal-to-noise ratio Keck spectra of ~ 50 intermediate luminosity broad-line AGNs at z ~ 0.4 and z ~ 0.6, to measure stellar velocity dispersion, and HST (ACS and NICMOS) images of the same objects (~ 40 so far), to measure bulge luminosity from the two-dimensional AGN-galaxy decomposition analysis. In this paper, we will summarize the main results on the MBH–σ and MBH–bulge luminosity relations and their evolution to the present-day universe. The measured scaling relations show that the relations have evolved significantly in the past 6 billion years, and that black hole growth predates the final galaxy assembly.

scholarly journals Navarro-Frenk-White dark matter profile and the dark halos around disk systems

2020 ◽  
Vol 643 ◽  
pp. A161
Author(s):  
R. Dehghani ◽  
P. Salucci ◽  
H. Ghaffarnejad
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Rotational Velocity ◽  
Stellar Disk ◽  
Scaling Relations ◽  
Physical Context ◽  
The Galaxy ◽  
Current Mass ◽  
Supernova Explosions ◽  
Low Surface Brightness Galaxies

Context. The Λ cold dark matter (ΛCDM) scenario is able to describe the Universe at large scales, but clearly shows some serious difficulties at small scales. The core-cusp question is one of these difficulties: the inner dark matter (DM) density profiles of spiral galaxies generally appear to be cored, without the r−1 profile that is predicted by N-body simulations in the above scenario. Aims. It is well known that in a more physical context, the baryons in the galaxy might backreact and erase the original cusp through supernova explosions. Before the efficiency and the presence of this effect is investigated, it is important to determine how wide and frequent the discrepancy between observed and N-body-predicted profiles is and what its features are. Methods. We used more than 3200 quite extended rotation curves (RCs) of good quality and high resolution of disk systems that included normal and dwarf spirals as well as low surface brightness galaxies. The curves cover all magnitude ranges. All these RCs were condensed into 26 coadded RCs, each of them built with individual RCs of galaxies of similar luminosity and morphology. We performed mass models of these 26 RCs using the Navarro-Frenk-White (NFW) profile for the contribution of the DM halo to the circular velocity and the exponential Freeman disk for the contribution of the stellar disk. Results. The fits are generally poor in all the 26 cases: in several cases, we find χred2 > 2. Moreover, the best-fitting values of three parameters of the model (c, MD, and Mvir) combined with those of their 1σ uncertainty clearly contradict well-known expectations of the ΛCDM scenario. We also tested the scaling relations that exist in spirals with the outcome of the current mass modeling: the modeling does not account for these scaling relations. Conclusions. The results of testing the NFW profile in disk systems indicate that this DM halo density law cannot account for the kinematics of the whole family of disk galaxies. It is therefore mandatory for the success of the ΛCDM scenario in any disk galaxy of any luminosity or maximum rotational velocity to transform initial cusps into the observed cores.

A compact guided-wave EMAT with pulsed electromagnet for ferromagnetic tube inspection

2020 ◽  
Vol 64 (1-4) ◽  
pp. 951-958
Author(s):  
Tianhao Liu ◽  
Yu Jin ◽  
Cuixiang Pei ◽  
Jie Han ◽  
Zhenmao Chen
Keyword(s):  
Power Plants ◽  
Signal To Noise Ratio ◽  
Small Diameter ◽  
Performance Testing ◽  
Guided Wave ◽  
High Signal ◽  
Receiver Coil ◽  
Signal To Noise ◽  
Corrosion Defects

Small-diameter tubes that are widely used in petroleum industries and power plants experience corrosion during long-term services. In this paper, a compact inserted guided-wave EMAT with a pulsed electromagnet is proposed for small-diameter tube inspection. The proposed transducer is noncontact, compact with high signal-to-noise ratio and unattractive to ferromagnetic tubes. The proposed EMAT is designed with coils-only configuration, which consists of a pulsed electromagnet and a meander pulser/receiver coil. Both the numerical simulation and experimental results validate its feasibility on generating and receiving L(0,2) mode guided wave. The parameters for driving the proposed EMAT are optimized by performance testing. Finally, feasibility on quantification evaluation for corrosion defects was verified by experiments.

Application of Novel Low Current OBIRCH Amplifier and Nanoprobing to Identify Subtle Leakages in Advanced Node Technologies

2018 ◽  
Author(s):  
Satish Kodali ◽  
Liangshan Chen ◽  
Yuting Wei ◽  
Tanya Schaeffer ◽  
Chong Khiam Oh
Keyword(s):  
Signal To Noise Ratio ◽  
Semiconductor Industry ◽  
Fault Isolation ◽  
Ring Oscillator ◽  
High Signal ◽  
The Novel ◽  
Resistance Change ◽  
Three Samples ◽  
Relative Threshold ◽  
First Time

Abstract Optical beam induced resistance change (OBIRCH) is a very well-adapted technique for static fault isolation in the semiconductor industry. Novel low current OBIRCH amplifier is used to facilitate safe test condition requirements for advanced nodes. This paper shows the differences between the earlier and novel generation OBIRCH amplifiers. Ring oscillator high standby leakage samples are analyzed using the novel generation amplifier. High signal to noise ratio at applied low bias and current levels on device under test are shown on various samples. Further, a metric to demonstrate the SNR to device performance is also discussed. OBIRCH analysis is performed on all the three samples for nanoprobing of, and physical characterization on, the leakage. The resulting spots were calibrated and classified. It is noted that the calibration metric can be successfully used for the first time to estimate the relative threshold voltage of individual transistors in advanced process nodes.

scholarly journals VS2 as saturable absorber for Q-switched pulse generation

Nanophotonics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 2569-2576 ◽  
Author(s):  
Lu Li ◽  
Lihui Pang ◽  
Qiyi Zhao ◽  
Yao Wang ◽  
Wenjun Liu
Keyword(s):  
Saturable Absorber ◽  
Nonlinear Optical ◽  
Modulation Depth ◽  
Signal To Noise Ratio ◽  
Transition Metal Dichalcogenides ◽  
Laser Cavity ◽  
Pulse Generation ◽  
High Signal ◽  
Power Pulse ◽  
Metal Dichalcogenides

AbstractTransition metal dichalcogenides have been widely utilized as nonlinear optical materials for laser pulse generation applications. Herein, we study the nonlinear optical properties of a VS2-based optical device and its application as a new saturable absorber (SA) for high-power pulse generation. Few-layer VS2 nanosheets are deposited on the tapered region of a microfiber to form an SA device, which shows a modulation depth of 40.52%. After incorporating the microfiber-VS2 SA into an Er-doped fiber laser cavity, passively Q-switched pulse trains could be obtained with repetition rates varying from 95 to 233 kHz. Under the pump power of 890 mW, the largest output power and shortest pulse duration are measured to be 43 mW and 854 ns, respectively. The high signal-to-noise ratio of 60 dB confirms the excellent stability of the Q-switching state. To the best of our knolowdge, this is the first illustration of using VS2 as an SA. Our experimental results demonstrate that VS2 nanomaterials have a large potential for nonlinear optics applications.

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