Intrinsic Degeneracy of Gravitational Lens Time Delays: The Case for a Simple Quadruple System in Λ Cold Dark Matter Cosmology

2003 ◽  
Vol 582 (1) ◽  
pp. 2-5 ◽  
Author(s):  
HongSheng Zhao ◽  
Bo Qin
Keyword(s):  
Dark Matter ◽  
Time Delays ◽  
Cold Dark Matter ◽  
Gravitational Lens ◽  
Quadruple System

scholarly journals Gravitational Lens Statistics as a Probe of Halo Profiles

2004 ◽  
Vol 220 ◽  
pp. 143-144
Author(s):  
Masamune Oguri
Keyword(s):  
Dark Matter ◽  
Structure Formation ◽  
Density Profile ◽  
Time Delays ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Gravitational Lens ◽  
Current Status ◽  
Formation Theory ◽  
Multiple Images

Recent development of the structure formation theory based on the cold dark matter scenario implies that a number of larger separation lensed quasars, for which a confirmed detection has not yet been achieved, will be observed in the ongoing large-scale surveys such as the 2dF survey and SDSS. We show that statistics of such large separation lenses can be a powerful probe of the density profile of dark halos. After we summarize the current status of the lens surveys in the 2dF and SDSS, we focus our discussion on what information can be extracted from these lens surveys. in addition, we also propose statistics of differential time delays between multiple images as an alternative probe of the density profile of dark halos.

scholarly journals Low-mass halo perturbations in strong gravitational lenses at redshift z ∼ 0.5 are consistent with CDM

2019 ◽  
Vol 485 (2) ◽  
pp. 2179-2193 ◽  
Author(s):  
E Ritondale ◽  
S Vegetti ◽  
G Despali ◽  
M W Auger ◽  
L V E Koopmans ◽  
...  
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Detection Threshold ◽  
Current Data ◽  
Gravitational Lens ◽  
Detection Sensitivity ◽  
Line Of Sight ◽  
Gravitational Lenses ◽  
Lepton Asymmetry ◽  
Low Mass

ABSTRACT We use a sample of 17 strong gravitational lens systems from the BELLS GALLERY survey to quantify the amount of low-mass dark matter haloes within the lensing galaxies and along their lines of sight, and to constrain the properties of dark matter. Based on a detection criterion of 10σ, we report no significant detection in any of the lenses. Using the sensitivity function at the 10σ level, we have calculated the predicted number of detectable cold dark matter (CDM) line-of-sight haloes to be μl = 1.17 ± 1.08, in agreement with our null detection. Assuming a detection sensitivity that improved to the level implied by a 5σ threshold, the expected number of detectable line-of-sight haloes rises to μl = 9.0 ± 3.0. Whilst the current data find zero detections at this sensitivity level (which has a probability of P$^{{\rm 5}\sigma }_{{\rm CDM}}(n_{\rm det}=0)$ = 0.0001 and would be in strong tension with the CDM framework), we find that such a low-detection threshold leads to many spurious detections and non-detections and therefore the current lack of detections is unreliable and requires data with improved sensitivity. Combining this sample with a subsample of 11 SLACS lenses, we constrain the half-mode mass to be log (Mhm) < 12.26 at the 2σ level. The latter is consistent with resonantly produced sterile neutrino masses ms < 0.8 keV at any value of the lepton asymmetry at the 2σ level.

Dark matter halo as the dispersional gravitational lens

2014 ◽  
Vol 29 (37) ◽  
pp. 1440002 ◽  
Author(s):  
L. M. Chechin
Keyword(s):  
Refractive Index ◽  
Dark Matter ◽  
Cold Dark Matter ◽  
Low Frequency ◽  
Gravitational Lens ◽  
Dark Matter Halo ◽  
Time Variability ◽  
Baryonic Matter ◽  
Galaxy Structure ◽  
X Ray

Based on the time-variability of the dark matter (DM) parameter of state (PoS) type of [Formula: see text], the conception of dispersional gravitational lens (DGL) was proposed. The dependency of refractive index of DM halo on its own global oscillations was found. It was shown that DM does not oscillate with optical or ultraviolet and X-ray diapasons, but it may oscillate with essentially low frequency — ϖ DM ≥10-15 Hz . Hence, it is possible to talk about the ultra weak DM oscillations, and the very cold dark matter (VCDM) particles whose masses are larger than m VCDM ≥10-42 eV . It was marked briefly that DM global oscillations will gradually pump with elastic energy the galaxy's baryonic matter. Hence, they may be the real reason of its subsequent fragmentation and the inner galaxy structure formation.

scholarly journals A high-resolution cosmological simulation of a strong gravitational lens

2021 ◽  
Author(s):  
Jack Richings ◽  
Carlos Frenk ◽  
Adrian Jenkins ◽  
Andrew Robertson ◽  
Matthieu Schaller
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Median Number ◽  
Gravitational Lens ◽  
Galactic Winds ◽  
Hydrodynamical Simulation ◽  
Cold Dark Matter Model ◽  
Lower Amplitude ◽  
Mass Functions

Abstract We present a cosmological hydrodynamical simulation of a 1013 M⊙ galaxy group and its environment (out to 10 times the virial radius) carried out using the Eagle model of galaxy formation. Exploiting a novel technique to increase the resolution of the dark matter calculation independently of that of the gas, the simulation resolves dark matter haloes and subhaloes of mass 5 × 106 M⊙. It is therefore useful for studying the abundance and properties of the haloes and subhaloes targeted in strong lensing tests of the cold dark matter model. We estimate the halo and subhalo mass functions and discuss how they are affected both by the inclusion of baryons in the simulation and by the environment. We find that the halo and subhalo mass functions have lower amplitude in the hydrodynamical simulation than in its dark matter only counterpart. This reflects the reduced growth of haloes in the hydrodynamical simulation due to the early loss of gas by reionisation and galactic winds and, additionally, in the case of subhaloes, disruption by enhanced tidal effects within the host halo due to the presence of a massive central galaxy. The distribution of haloes is highly anisotropic reflecting the filamentary character of mass accretion onto the cluster. As a result, there is significant variation in the number of structures with viewing direction. The median number of structures near the centre of the halo, when viewed in projection, is reduced by a factor of two when baryons are included.

scholarly journals Gravitational lensing study of cold dark matter-led galactic halo

2021 ◽  
pp. 2150089
Author(s):  
Samrat Ghosh ◽  
Arunava Bhadra ◽  
Amitabha Mukhopadhyay
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Cold Dark Matter ◽  
Galactic Halo ◽  
Gravitational Lens ◽  
Galactic Rotation ◽  
Spacetime Geometry ◽  
The Galaxy ◽  
Galactic Rotation Curve ◽  
Fisher Relation

In this work, the spacetime geometry of the halo region in spiral galaxies is obtained considering the observed flat galactic rotation curve feature, invoking the Tully–Fisher relation and assuming the presence of cold dark matter in the galaxy. The gravitational lensing analysis is performed treating the so-obtained spacetime as a gravitational lens. It is found that the aforementioned spacetime as the gravitational lens can consistently explain the galaxy–galaxy weak gravitational lensing observations and the lensing observations of the well-known Abell 370 and Abell 2390 galaxy clusters.

Bolometric Detection of Cold Dark Matter Candidates

1988 ◽  
Author(s):  
A. K. Drukier ◽  
Katherine Freese ◽  
Joshua Frieman
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Bolometric Detection
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