astro-ph.HE Archives

A comparison of measured element abundances in the Earth’s crust (24) (dotted line) with r-process portion (solid line) calculated using the r-process fractions from (23). Elements for which the calculated r-process fractions exceed 75% are labelled. These include the elements bromine, iodine, thorium and uranium, whose relevance to life on Earth is discussed in the text. -- astro-ph.HE

Astrochemistry, Astrogeology, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biophysics, Status Report

Do We Owe Our Existence To Gravitational Waves?

by Keith CowingFebruary 7, 2024February 7, 2024

Two heavy elements essential to human biology are thought to have been produced by the astrophysical r-process, which occurs in neutron-rich environments: iodine is a constituent of thyroid hormones that […]

Schematic diagram demonstrating interstellar ices within dark clouds made of molecular hydrogen being processed by photochemistry involving the production of electronically excited water and radiation chemistry involving the production of ionized water and secondary electrons. This work focuses on the interaction depicted in the second of the two CRs (blue lines) in which a CR interacts in the ice mantle to produce secondary electrons. Reproduced from Ref. 4. Copyright 2019, The Royal Society of Chemistry. -- astro-ph.HE

Astrochemistry, Status Report

The Role of Low-energy (< 20 eV) Secondary Electrons in the Extraterrestrial Synthesis of Prebiotic Molecules

by Keith CowingDecember 6, 2023December 6, 2023

We demonstrate for the first time that Galactic cosmic rays with energies as high as 1e10 eV can trigger a cascade of low-energy (< 20 eV) secondary electrons that could […]

Schematic diagrams highlighting the interesting components of emission from a binary neutron star merger at two different temporal and spatial scales. In (a), the system is shown at sub-parsec scales and within the first few years after the merger. The locations of gamma-ray emission in the dynamical ejecta and the cocoon surrounding the jet are highlighted, as well as the X-ray emission from the interaction between the jet and the interstellar medium (ISM). While the jet and cocoon emission are short-lived, the afterglow produces continuum emission for many years. Only the emitted X-rays produce the fluence that could be lethal. The kilonova, i.e., the UV/optical/IR emission powered by radioactivity in the ejecta, is also shown for additional context, but is undetectable after a week. In (b), the larger, late-time structure of the remnant is shown with the long-since dissipated jet location indicated. The explosion from the merger will launch a strong shock that sweeps out a bubble-like structure as it expands through the ISM, which is a source of potentially threatening cosmic rays. -- astro-ph.HE

Astronomy & Telescopes, Extinction events, Radiation, Status Report

Could A Kilonova Kill: A Threat Assessment

by Keith CowingOctober 19, 2023October 19, 2023

Binary neutron star mergers (BNS) produce high-energy emissions from several physically different sources, including a gamma-ray burst (GRB) and its afterglow, a kilonova, and, at late times, a remnant many […]

Upper limits on the transmitter rates as a function of EIRPmin in this work and previous studies are presented. The dot-dash lines show our result for the case of GBT-L, using the statistical method described in Section 3.2.1. The results based on the crossmatching method are shown in arrows, with different colours corresponding to different surveys. Other markers in different colours represent the upper limits presented in previous studies (Gray & Mooley 2017; Enriquez et al. 2017; Price et al. 2020; Wlodarczyk-Sroka et al. 2020; Garrett & Siemion 2023). The grey dotted line connecting the previous most constraining values reported by Wlodarczyk-Sroka et al. (2020) and Garrett & Siemion (2023) was introduced as terra incognita (Garrett & Siemion 2023). The terra incognita indicates the line below which the parameter space needs to be explored at better sensitivity and a broader search area. -- astro-ph.HE

Astronomy & Telescopes, SETI & Technosignatures, Status Report

Upper Limits On Transmitter Rate Of Extragalactic Civilizations Placed By Breakthrough Listen Observations

by Keith CowingApril 10, 2023April 10, 2023

The Search for Extra-Terrestrial Intelligence (SETI) has been conducted for over sixty years, yet no technosignatures have been identified. Previous studies have focused on stars in our galaxy, with few […]

AI - Data - Apps - Cybernetics, Astronomy & Telescopes, Intelligence & Language, Interstellar, SETI & Technosignatures, Status Report

Black Holes As Tools For Quantum Computing By Advanced Extraterrestrial Civilizations

by Keith CowingFebruary 14, 2023

We explain that black holes are the most efficient capacitors of quantum information. It is thereby expected that all sufficiently advanced civilizations ultimately employ black holes in their quantum computers.

Intelligence & Language, Interstellar, SETI & Technosignatures, Status Report

Black Holes As Tools For Quantum Computing By Advanced Extraterrestrial Civilizations

by Keith CowingJanuary 24, 2023January 24, 2023

Astronomy & Telescopes, Extinction events, Habitable Zones, Press Release, Radiation

X-Ray Luminous Supernovae: Threats To Terrestrial Biospheres

by Keith CowingOctober 24, 2022October 24, 2022

The spectacular outbursts of energy associated with supernovae (SNe) have long motivated research into their potentially hazardous effects on Earth and analogous environments.

Press Release, SETI & Technosignatures

Constraints On Extragalactic Transmitters Via Breakthrough Listen

by Keith CowingSeptember 19, 2022September 19, 2022

The Breakthrough Listen Initiative has embarked on a comprehensive SETI survey of nearby stars in the Milky Way that is vastly superior to previous efforts as measured by a wide […]

Astrochemistry

Future Radioisotope Measurements To Clarify The Origin Of Deep-ocean 244Pu

by Keith CowingDecember 20, 2021

244Pu has been discovered in deep-ocean deposits spanning the past 10 Myr, a period that includes two 60Fe pulses from nearby supernovae. 244Pu is among the heaviest r-process products, and […]

SETI & Technosignatures

The Breakthrough Listen Search For Intelligent Life Near the Galactic Center I

by Keith CowingApril 29, 2021

A line-of-sight towards the Galactic Center (GC) offers the largest number of potentially habitable systems of any direction in the sky. The Breakthrough Listen program is undertaking the most sensitive […]