Archivi tag: clusters of galaxies

Cosmology and the Epoch of Reionization

During the past decades, significant efforts have been made to investigate the physics in the late time Universe and during the Epoch of Reionization. Theoretical studies, advanced numerical models and observations have led to great insights into the astrophysics as well as the Cosmology present from redshift zero all the way up to redshifts of order 15. However, they also generated a plethora of interesting but thus far unanswered questions. Continua a leggere Cosmology and the Epoch of Reionization

The Role of Hydrogen in the Evolution of Galaxies

As the most abundant element in the Universe, hydrogen is an ubiquitous tracer of structures at various scales and plays a fundamental role in galaxy formation. Accretion of hydrogen from the intergalactic medium (IGM) feeds galaxies with the raw material necessary for the formation of stars. Continua a leggere The Role of Hydrogen in the Evolution of Galaxies

Cosmology and relativistic astrophysics

The 2014 year marks the 100th anniversary of Yakov Zeldovich. The conference will commemorate his contribution to astronomy by concentrating on recent progress in cosmology and high energy astrophysics, the areas where his ideas laid the basis for revolutionary advances. Continua a leggere Cosmology and relativistic astrophysics

The X-ray Universe

The XMM-Newton Science Operations Centre is organising a major astrophysical symposium from Monday 16th to Thursday 19th of June 2014 in Dublin, Ireland. The symposium is the fourth international meeting in the series “The X-ray Universe”. The intention is to gather a general collection of research in high energy astrophysics. The symposium will provide a showcase for results, discoveries and expectations from current and future X-ray missions. Continua a leggere The X-ray Universe

The decay of sterile neutrinos as signal of dark matter presence

Un gruppo di astrofisici dell’Università di Leiden, guidati da Alexey Boyarsky, potrebbero aver identificato alcune tracce della presenza di materia scura attraverso la rivelazione di una nuova particella, il neutrino sterile, un ipotetico tipo di neutrino che non interagisce con nessuna delle interazioni fondamentali. Intanto, qualche giorno fa, un altro gruppo di ricercatori di Harvard hanno riportato risultati simili.

The two groups this week reported that they have found an indirect signal from dark matter in the spectra of galaxies and clusters of galaxies. They made this discovery independent of one another, but came to the same conclusion: a tiny spike is hidden in the X-ray spectra of the Perseus galaxy cluster, at a frequency that cannot be explained by any known atomic transition. The Harvard group see the same spike in many other galaxy clusters, while Boyarsky also finds it in the nearby Andromeda galaxy. The researchers put it down to the decay of a new kind of neutrino, called ‘sterile’ because it has no interaction with other known neutrinos.

A sterile neutrino does have mass, and so could be responsible for the missing dark matter.

The first indications for the existence of dark matter in space were found more than eighty years ago, but there are still many questions surrounding this invisible matter. Sterile neutrinos are a highly attractive candidate for the dark matter particle, because they only call for a minor extension of the already known and extensively tested standard model for elementary particles. Boyarsky and his colleagues have already had this extension of the standard model ready for some time, but were waiting for the first observation of the mysterious particle. Measurements at higher resolution will shed light on the matter, and there is reason to hope that the spectral line just discovered will finally eliminate the problem of the missing mass.

University of Leiden: Glimmer of light in the search for dark matter

arXiv: An unidentified line in X-ray spectra of the Andromeda galaxy and Perseus galaxy cluster 

arXiv: Detection of An Unidentified Emission Line in the Stacked X-ray spectrum of Galaxy Clusters