After primordial inflation

D. V. Nanopoulos, K. A. Olive, M. Srednicki
We consider the history of the early universe in the locally supersymmetric model we have previously discussed. We pay particular attention to the requirement of converting the quanta of the field which drives primordial inflation (inflatons) to ordinary particles which can produce the cosmological baryon asymmetry without producing too many gravitinos. An inflaton mass of about 1013 GeV (a natural value in our model) produces a completely acceptable scenario.
Read more at https://lib-extopc.kek.jp/preprints/PDF/1983/8305/8305219.pdf

Is our universe one of many?

BY KER THAN
As physicists have delved deeper and deeper into nature’s mysteries, they have been forced to accept the unsettling fact that our universe is suspiciously fine-tuned to support life. The amount of matter in the universe, the mass of the electron, the strength of gravity – if the value of any of these deviated only a tiny bit from what they actually are, then galaxies and stars could not form and biological life could not exist. The best theory that physicists have come up with to explain this cosmic coincidence is called the String Theory Landscape.

The String Theory Landscape combines elements from two of the strangest and most enduring ideas in modern physics – string theory and cosmic inflation – to argue that we live in a multiverse made up of infinitely many “pocket universes,” of which our perfectly calibrated universe is just one. This five-part series tells the story of how theoretical physicists at Stanford helped develop the String Theory Landscape – and in the process sparked a fierce and still ongoing debate about what science is and what it should be…

Read more at https://news.stanford.edu/2018/09/10/landscape-theory/

Introduction to neutrino astronomy

neutrino flux

Energy dependence of the neutrino fluxes produced by the different nuclear processes in the Sun

Andrea Gallo Rosso, Carlo Mascaretti, Andrea Palladino, Francesco Vissani
This writeup is an introduction to neutrino astronomy, addressed to astronomers and written by astroparticle physicists. While the focus is on achievements and goals in neutrino astronomy, rather than on the aspects connected to particle physics, we will introduce the particle physics concepts needed to appreciate those aspects that depend on the peculiarity of the neutrinos. The detailed layout is as follows: In Sect.~1, we introduce the neutrinos, examine their interactions, and present neutrino detectors and telescopes. In Sect.~2, we discuss solar neutrinos, that have been detected and are matter of intense (theoretical and experimental) studies. In Sect.~3, we focus on supernova neutrinos, that inform us on a very dramatic astrophysical event and can tell us a lot on the phenomenon of gravitational collapse. In Sect.~4, we discuss the highest energy neutrinos, a very recent and lively research field. In Sect.~5, we review the phenomenon of neutrino oscillations and assess its relevance for neutrino astronomy. Finally, we offer a brief overall assessment and a summary in Sect.~6. The material is selected – i.e., not all achievements are reviewed – and furthermore it is kept to an introductory level, but efforts are made to highlight current research issues. In order to help the beginner, we prefer to limit the list of references, opting whenever possible for review works and books.

Read more at https://arxiv.org/pdf/1806.06339.pdf

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Gravitational Waves: A New Astronomy


Luc Blanchet
Contemporary astronomy is undergoing a revolution, perhaps even more important than that which took place with the advent of radioastronomy in the 1960s, and then the opening of the sky to observations in the other electromagnetic wavelengths. The gravitational wave detectors of the LIGO/Virgo collaboration have observed since 2015 the signals emitted during the collision and merger of binary systems of massive black holes at a large astronomical distance. This major discovery opens the way to the new astronomy of gravitational waves, drastically different from the traditional astronomy based on electromagnetic waves. More recently, in 2017, the detection of gravitational waves emitted by the inspiral and merger of a binary system of neutron stars has been followed by electromagnetic signals observed by the γ and X satellites, and by optical telescopes. A harvest of discoveries has been possible thanks to the multi-messenger astronomy, which combines the information from the gravitational wave with that from electromagnetic waves. Another important aspect of the new gravitational astronomy concerns fundamental physics, with the tests of general relativity and alternative theories of gravitation, as well as the standard model of cosmology.
Read more at https://arxiv.org/pdf/1805.08563.pdf

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Lets Talk About Black Hole Singularities

Abraham Loeb
Does the collision of black hole singularities imprint an observable quantum signature on the resulting gravitational wave signal?

The singularities at the centers of astrophysical black holes mark the breakdown of Einstein’s theory of gravity, General Relativity. They represent the only breakdown sites accessible to experimentalists, since the other known singularity, the Big Bang,is believed to be invisible due to the vast expansion that occurred afterwards during cosmic inflation…
Read more https://arxiv.org/ftp/arxiv/papers/1805/1805.05865.pdf