Archivi tag: cosmic inflation

Primordial gravitational waves: a possible major discovery could be announced today

Alle ore 17 di oggi, alcuni astronomi dell’Harvard-Smithsonian Center for Astrophysics potrebbero annunciare una scoperta clamorosa in cosmologia, il che darebbe enfasi e valore ad un modello che descrive le primissime fasi iniziali della storia cosmica e che risale tra la fine degli anni ’70 e gli inizi degli anni ’80: l’inflazione cosmica. L’obiettivo è quello di rivelare le onde gravitazionali “primordiali” che rappresentano una sorta di residuo fossile del Big Bang da cui si è originato l’Universo circa 14 miliardi di anni fa. Dunque, se saranno mostrate forti evidenze della presenza di onde gravitazionali primordiali, allora si potrà parlare di una scoperta sensazionale che potrebbe modificare le nostre conoscenze fondamentali in cosmologia e fisica delle particelle.

Per saperne di più:

The Harvard-Smithsonian Center for Astrophysics (CfA) will host a press conference at 12:00 noon EDT (16:00 UTC) on Monday, March 17th, to announce a major discovery.

Video > live streaming at 11:55 a.m. EDT from the link at http://www.cfa.harvard.edu/news/news_conferences.html

Press release > it will be available here: http://www.cfa.harvard.edu/news/2014-05

More at viXra log: “first direct evidence of cosmic inflation” BICEP2 results

Paper: http://bicepkeck.org/b2_respap_arxiv_v1.pdf

BICEP2 2014 Results Release

New hints on the primordial gravitational waves in the CMB

Grazie ad una serie di osservazioni realizzate mediante il telescopio del Polo Sud in Antartide e l’osservatorio spaziale Herschel, gli astronomi sono stati in grado di rivelare per la prima volta un segnale molto debole nella radiazione cosmica di fondo che potrebbe fornire informazioni di vitale importanza sui primi momenti della creazione dell’Universo. Le misure di questo segnale elusivo sono state realizzate studiando il modo con cui la luce viene deflessa nel suo viaggio cosmico prima di arrivare sulla Terra, passando attraverso gli ammassi di galassie e la distribuzione della materia scura. La scoperta permette di fornire nuovi indizi su come rivelare le onde gravitazionali che si sono originate durante l’epoca dell’inflazione cosmica, un risultato cruciale anticipato dalla missione Planck (post).

The relic radiation from the Big Bang, the Cosmic Microwave Background, or CMB, was imprinted on the sky when the Universe was just 380 000 years old. Today, some 13.8 billion years later, we see it as a sky filled with radio waves at a temperature of just 2.7 degrees above absolute zero. Tiny variations in this temperature, around a few tens of millionths of a degree, reveal density fluctuations in the early Universe corresponding to the seeds of galaxies and stars we see today. The most detailed all-sky map of temperature variations in the background was revealed by Planck in March (post). But the CMB also contains a wealth of other information. A small fraction of the light is polarised, like the light we can see using polarised glasses. This polarised light has two distinct patterns: E-modes and B-modes. E-modes were first found in 2002 with a ground-based telescope. B-modes, however, are potentially much more exciting to cosmologists, although much harder to detect. They can arise in two ways. The first involves adding a twist to the light as it crosses the Universe and is deflected by galaxies and dark matter, a phenomenon known as gravitational lensing. The second has its roots buried deep in the mechanics of a very rapid phase of enormous expansion of the Universe, which cosmologists believe happened just a tiny fraction of a second after the Big Bang, namely the ‘inflation’.

The new study has combined data from the South Pole Telescope and Herschel to make the first detection of B-mode polarisation in the CMB due to gravitational lensing.

This measurement was made possible by a clever and unique combination of ground-based observations from the South Pole Telescope, which measured the light from the Big Bang, with space-based observations from Herschel, which is sensitive to the galaxies that trace the dark matter which caused the gravitational lensing,” says Joaquin Vieira, of the California Institute of Technology and the University of Illinois at Urbana-Champaign, who led the Herschel survey used in the study. By using Herschel’s observations, the scientists mapped the gravitational lensing material along the line of sight, and then searched for correlations between that pattern and the polarised light coming from the CMB, as measured by the South Pole Telescope. “It’s an important checkpoint that we’re able to detect this small lensing B-mode signal and it bodes well for our ability to ultimately measure an even more elusive type of B-mode created during the inflationary Big Bang”, adds Duncan Hanson of McGill University, Montreal, Canada. Scientists believe that during inflation, violent collisions between clumps of matter and between matter and radiation, should have created a sea of gravitational waves. Today, those waves would be imprinted in a primordial B-mode component of the CMB.

Finding such a signal would yield crucial information about the very early Universe, well before the time when the CMB itself was generated, and would provide confirmation of the inflation scenario.

In 2014, new results will be released from ESA’s Planck, and the most eagerly anticipated is whether primordial B-modes have been detected. In the meantime, Herschel has helped to point the way.

ESA: HERSCHEL THROWS NEW LIGHT ON OLDEST COSMIC LIGHT

arXiv: Detection of B-mode Polarization in the Cosmic Microwave Background with Data from the South Pole Telescope

arXiv: A CMB lensing mass map and its correlation with the cosmic infrared background

A new approach to exploring quantum gravity

I fisici Lawrence Krauss e Frank Wilczek, rispettivamente dell’Arizona State University e dell’Australian National University, hanno pubblicato un lavoro in cui essi propongono una nuovo approccio sulla possibilità di quantizzare la forza di gravità misurando la polarizzazione della radiazione cosmica di fondo. Secondo gli scienziati, questo metodo potrebbe portare ad una connessione tra la radiazione cosmica di fondo e le onde gravitazionali causate dall’inflazione cosmica durante le epoche primordiali della storia cosmica.

Physicists, as most are aware, have been stymied in their efforts to discover a way to unify quantum mechanics and gravity, most scientists in the field believe there is likely a gravity particle they call it a graviton, that carries the force known as gravity. No one of course has ever seen one, or been able to prove it exists. This is because, they say, of how weak it is compared to the other forces, such as electromagnetism, to be able to see it, some have suggested, would require a device so massive that it would collapse in on itself into a black hole. For this reason, some researchers have suggested that we will never be able to see it.

In their paper, Krauss and Wilczek suggest that it might not be necessary to see it, because there might be a way to infer its existence by measuring the CMB.

Their idea is that in the early Universe, just after the Big Bang, as inflation was occurring, gravitational waves should have been created which in turn would have caused photons present in the CMB to scatter in a certain pattern. Finding that pattern would mean finding evidence of a particle that was carrying the gravitational force, the graviton. And if evidence for the existence of a graviton could be found, then physicists would finally have their “universal theory”. They add that they believe that dimensional analysis could provide a link between those early gravitational waves and Planck’s constant, which is of course used in quantum mechanics. There are a couple of issues with the new theory, the first is that technology does not yet exist to measure the CMB in a way that would allow scientists to detect those early gravitational waves and another is proving that any polarization found in the CMB can indeed be attributable to gravitational waves and not some other mechanism, force or process.

arXiv: Using Cosmology to Establish the Quantization of Gravity