Soft gamma ray lines from radioactive decay
of 26Al and 60Fe as well as annihilation of positrons have been
observed from the Milky Way. The respective emission contains information
about the ejecta of supernovae, massive-star winds and possibly winds related to neutron stars and
black holes. The distinct spatial structure of the different lines allows
to trace the flow of the ejecta...
The most metal-poor low-mass stars formed in the very Early Universe, at about 300 Myr after the Big Bang, are still observable today in the Galactic Halo. These stars hold crucial information of the early epochs of the Universe, such as the properties of the first stars and supernovae and the early chemical evolution of the Universe, and the formation of low-mass stars in the Early Universe....
Very metal-poor stars that have [Fe/H]$< -2$ and are enhanced in C relative to Fe ([C/Fe]$>0.7$) but have low enhancement of heavy elements ([Ba/Fe]$<0$) are known as carbon-enhanced metal-poor-no (CEMP-no) stars. These stars are thought to be produced from the interstellar medium (ISM) polluted by the supernova (SN) ejecta of the very first generation (Pop III) massive stars. Although...
The 12C/13C isotopic ratio is an important diagnostic tool in astrophysics, providing insights into the formation and evolution of stars and galaxies. In this talk, we will discuss the measurement of this ratio using data from the ESPRESSO instrument, which is one of the most powerful spectrographs in the world.
We will focus on the information obtained from the oldest stars in the Milky...
TBD
The Majoron, the Goldstone boson from the spontaneous lepton number symmetry breaking, is a theoretically and phenomenologically well-motivated hypothetical particle. As it is typically believed to be long-lived, it has the potential power of altering the big bang nucleosynthesis.
We find that non-thermal energetic neutrinos produced by decays of Majoron can cause various neutrino-induced...
Nuclear chronometer provides an independent dating technique for the cosmos by predicting the ages of the oldest stars. Similar to geochronology, the ages are determined by comparing the present and initial abundances of long-lived radioactive nuclides. In nuclear cosmochronology, the present abundances can be obtained from the astrophysical observations whereas the initial abundances have to...
