Periodic Reporting for period 4 - JetNS (Relativistic Jets in Astrophysics -Compact binary mergers, Gamma-Ray Bursts, and Beyond)
Periodo di rendicontazione: 2023-07-01 al 2024-12-31
What is the origin of the heavy element (such as gold) we find on Earth? What is the source of the light that follows gravitational waves observed from mergers of two neutron stars? How well binary neutron star mergers can be used to measure the expansion rate of the Universe? What are the sources of high-energy neutrinos seen on Earth? Are all stars exploding via the same mechanism? These are some of the puzzles that have emerged with the rapid progress of time domain astronomy. Relativistic jets in exploding stars and in binary neutron star and neutron star black hole mergers hold the key to these, and other, seemingly unrelated broad-impact questions. These jets also serve as a laboratory of physics at the most extreme conditions, which can never be explored on Earth and that Nature kindly provides us.
This project carries out a new forefront study of how relativistic jets interact with their environment and of its numerous implications, focusing on compact binary mergers exploding stars. The goal is to answer the aforementioned big questions as well as many other questions which are more specific to physics and astrophysics. This is done using theoretical analytic study, extensive high-performance computing simulations and comparison to the immense continuous flow of new astrophysical observations.
This project carries out a new forefront study of how relativistic jets interact with their environment and of its numerous implications, focusing on compact binary mergers exploding stars. The goal is to answer the aforementioned big questions as well as many other questions which are more specific to physics and astrophysics. This is done using theoretical analytic study, extensive high-performance computing simulations and comparison to the immense continuous flow of new astrophysical observations.
The project explores several avenues in parallel. Below I give some details on two of those.
(i) The physics of binary neutron star and neutron star black hole mergers (a.k.a compact binary mergers):
We wrote a comprehensive review of the subject in Physics Reports. This review summarizes the current knowledge on the subject and expands it in some areas, focusing on the light emitted following the merger. The review was followed by a series of novel studies on the subject. For example, the material that is thrown out of the merger glows in optical and IR due to the power of radioactive decay of the very heavy elements synthesized during the merger. We carried out a detailed calculation of the heat deposited by this radioactive decay and derived an improved method to calculate the resulting emitted light. Another example is a study of the detectability of the relativistic jet that is launched following the merger, where we found that the emission from the jet is expected to be detected only if it is pointing not too far away from us.
(ii) The propagation of relativistic jets in dense medium
We carried out a large set of simulations that follows the propagation of various types of jets in dense medium, as expected in cases of exploding stars or compact binary mergers. We focused on the structure that the jets attain due to this interaction after they emerge out of the dense medium.
(i) The physics of binary neutron star and neutron star black hole mergers (a.k.a compact binary mergers):
We wrote a comprehensive review of the subject in Physics Reports. This review summarizes the current knowledge on the subject and expands it in some areas, focusing on the light emitted following the merger. The review was followed by a series of novel studies on the subject. For example, the material that is thrown out of the merger glows in optical and IR due to the power of radioactive decay of the very heavy elements synthesized during the merger. We carried out a detailed calculation of the heat deposited by this radioactive decay and derived an improved method to calculate the resulting emitted light. Another example is a study of the detectability of the relativistic jet that is launched following the merger, where we found that the emission from the jet is expected to be detected only if it is pointing not too far away from us.
(ii) The propagation of relativistic jets in dense medium
We carried out a large set of simulations that follows the propagation of various types of jets in dense medium, as expected in cases of exploding stars or compact binary mergers. We focused on the structure that the jets attain due to this interaction after they emerge out of the dense medium.
By the end of the project we will use the results of the theoretical study obtained so far, as well as those that will be obtained in the coming year, together with available observations to address the high impact questions listed above. We will also derive (i) General models for the propagation of relativistic jets in various media types; (ii) Improved modeling of the light generated by jet-media interaction following compact binary mergers; (iii) Estimates of the neutrino signal from jet-media interaction in exploding stars; and (iv) Constraints on the role of jets in exploding stars.