The present status of the decaying neutrino theory

The present status of the decaying neutrino theory is reviewed. Three recent developments are highlighted: ( a ) the proposal that the dark matter in rich clusters of galaxies is mainly baryonic; ( b ) the implications of the hypothesis that decay photons are the solution of the C 0 /CO ratio problem; ( c ) the strong supporting evidence from recent observations with the Hubble space telescope.

2001 ◽  
Vol 18 (2) ◽  
pp. 182-185
Author(s):  
Geraint F. Lewis

AbstractThe true nature of dark matter in the universe still eludes us. This paper discusses a new test for the detection of stellar mass compact dark matter in galaxy clusters by observing its gravitational lensing influence on the surface brightness of giant luminous arcs. If dark matter is in the form of stellar mass compact objects, then the extremes of such variability are accessible to a monitoring campaign with the Hubble Space Telescope. With the advent of the Next Generation Space Telescope, cluster dark matter in the form of compact objects will induce a ubiquitous ‘shimmering’ of the giant arcs.


Author(s):  
Geoff Cottrell

Each question that telescopes have helped answer has led to new questions: what is dark matter and dark energy? How did the first galaxies form? Are there habitable, Earth-like exoplanets? To address these questions, a new generation of telescopes are being built. ‘The next telescopes’ describes some of these, including the three extremely large infrared/optical telescopes, equipped with adaptive optics systems, due to start operating in the next decade. Other new telescopes discussed are the Square Kilometre Array, a radio telescope that will soon be the world’s largest scientific instrument, and the James Webb Space Telescope due to be launched in 2018, which is the 100 times more powerful successor to the Hubble Space Telescope.


2021 ◽  
Vol 914 (1) ◽  
pp. L12
Author(s):  
Zili Shen ◽  
Shany Danieli ◽  
Pieter van Dokkum ◽  
Roberto Abraham ◽  
Jean P. Brodie ◽  
...  

2020 ◽  
Vol 495 (3) ◽  
pp. 3192-3208
Author(s):  
Liang Dai ◽  
Alexander A Kaurov ◽  
Keren Sharon ◽  
Michael Florian ◽  
Jordi Miralda-Escudé ◽  
...  

ABSTRACT We study the highly magnified arc SGAS J122651.3+215220 caused by a star-forming galaxy at zs = 2.93 crossing the lensing caustic cast by the galaxy cluster SDSS J1226+2152 (zl = 0.43), using Hubble Space Telescope observations. We report in the arc several asymmetric surface brightness features whose angular separations are a fraction of an arcsecond from the lensing critical curve and appear to be highly but unequally magnified image pairs of underlying compact sources, with one brightest pair having clear asymmetry consistently across four filters. One explanation of unequal magnification is microlensing by intracluster stars, which induces independent flux variations in the images of individual or groups of source stars in the lensed galaxy. For a second possibility, intracluster dark matter subhaloes invisible to telescopes effectively perturb lensing magnifications near the critical curve and give rise to persistently unequal image pairs. Our modelling suggests, at least for the most prominent identified image pair, that the microlensing hypothesis is in tension with the absence of notable asymmetry variation over a six-year baseline, while subhaloes of ∼106–$10^8\, \mathrm{ M}_\odot$ anticipated from structure formation with cold dark matter typically produce stationary and sizable asymmetries. We judge that observations at additional times and more precise lens models are necessary to stringently constrain temporal variability and robustly distinguish between the two explanations. The arc under this study is a scheduled target of a Director’s Discretionary Early Release Science program of the James Webb Space Telescope, which will provide deep images and a high-resolution view with integral field spectroscopy.


1996 ◽  
Vol 173 ◽  
pp. 113-118 ◽  
Author(s):  
J.P. Kneib ◽  
G. Soucail

The gravitational lensing of faint background galaxies by rich clusters is emerging as a very efficient method both to constrain the mass distribution of clusters of galaxies and to probe the statistical properties of faint background galaxies. We review results concerning the cores of cluster lenses, where recent Hubble Space Telescope (HST) images are giving new insights into the gravitational distortion phenomena.


2015 ◽  
Vol 11 (A29B) ◽  
pp. 795-796
Author(s):  
Markus Rexroth

AbstractFlexion is the second order weak gravitational lensing effect responsible for the arclike appearance of sources. It is highly sensitive to dark matter substructure and can greatly increase the resolution of mass maps, but it is very hard to measure. We present an automated flexion measurement pipeline for Hubble Space Telescope data and a preliminary application to the Frontier Fields cluster MACSJ0416.1-2403.


Author(s):  
TIM SCHRABBACK ◽  
PATRICK SIMON ◽  
THOMAS ERBEN ◽  
PETER SCHNEIDER ◽  
JAN HARTLAP ◽  
...  

2020 ◽  
Vol 895 (1) ◽  
pp. L4 ◽  
Author(s):  
Shany Danieli ◽  
Pieter van Dokkum ◽  
Roberto Abraham ◽  
Charlie Conroy ◽  
Andrew E. Dolphin ◽  
...  

2015 ◽  
Vol 11 (A29B) ◽  
pp. 751-754
Author(s):  
Jennifer Lotz ◽  

AbstractExceptionally deep observations of the distant universe with the Hubble Space Telescope have consistently pushed the frontiers of human knowledge. How deep can we go? What are the faintest and most distant galaxies we can see with the Hubble Space Telescope now, before the launch of the James Webb Space Telescope? This is the challenge taken up by the Frontier Fields, a director's discretionary time campaign with HST and the Spitzer Space Telescope to see deeper into the universe than ever before. The Frontier Fields combines the power of HST with the natural gravitational telescopes of high-magnification clusters of galaxies to produce the deepest observations of clusters and their lensed galaxies ever obtained. I will review the original goals of the Frontier Fields program and its progress over the last several years. In addition to pushing forward the study of the most distant galaxies, the Frontier Fields have been transformative in the study of galaxy clusters and their lensing properties. Finally, I will discuss the prospects for studying galaxies at cosmic dawn with JWST, extremely large ground-based telescopes, and future space missions over the next decade and beyond.


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