BEGIN:VCALENDAR VERSION:2.0 PRODID:-//linuxsoftware.nz//NONSGML Joyous v1.4//EN BEGIN:VEVENT SUMMARY:Dark Matter in Compact Stars DTSTART:20250925T143000Z DTEND:20250925T160000Z DTSTAMP:20260703T131958Z UID:4c9879fb-dee9-4f62-b3f8-387f509cb15d SEQUENCE:2 CREATED:20250925T091752Z DESCRIPTION:Compact stellar objects are promising cosmic laboratories to t est fundamental interactions\, in particular they could shed light on the nature of dark matter (DM). DM captured by the strong gravitational field of these stellar remnants transfers kinetic energy to the star during the collision. This together with further DM annihilation in the stellar inter ior can have various observational consequences such as the anomalous heat ing of old compact stars and compact star destruction for non-annihilating DM. We have improved former calculations of the capture and thermalizatio n rates in both white dwarfs (WDs) and neutron stars (NSs)\, making little approximations about the physics of compact stars. While DM deposits its kinetic energy in the star quite quickly\, for appreciable annihilation he ating to be achieved\, capture and annihilation processes should reach a s tate of equilibrium. We also revisit the calculation of the capture-annihi lation equilibrium timescales in neutron stars. For NSs\, we show that cap ture-annihilation equilibrium\, and hence maximal annihilation heating\, c an be achieved without complete thermalization of the captured dark matter for all types of dark matter - baryon interactions. This includes cases w here the scattering or annihilation cross sections are momentum or velocit y suppressed in the non-relativistic limit. For scattering cross sections that saturate the capture rate\, we find that capture-annihilation equilib rium is typically reached on a timescale of less than a year for vector in teractions and 10 thousand years for scalar interactions. For fermionic no n-annihilating heavy DM\, we also revisit black hole (BH) formation\, accr etion\, and evaporation. We find that previous results on the DM-nucleon s cattering cross section for a NS to be destructed by a BH from accumulated DM can be relaxed by a few orders of magnitude. LAST-MODIFIED:20250925T091806Z LOCATION:DF Seminar Room (2-8.3)\, 2nd floor of Physics Building URL:http://df.vps.tecnico.ulisboa.pt/pt/eventos/dark-matter-in-compact-sta rs/ X-ALT-DESC;FMTTYPE=text/html:

Compact stellar obj ects are promising cosmic laboratories to test fundamental interactions\, in particular they could shed light on the nature of dark matter (DM). DM captured by the strong gravitational field of these stellar remnants trans fers kinetic energy to the star during the collision. This together with f urther DM annihilation in the stellar interior can have various observatio nal consequences such as the anomalous heating of old compact stars and co mpact star destruction for non-annihilating DM.

We have improved former calculations of the capture and thermalization rates in both white dwarfs (WDs) and neutron stars (NSs)\, making little approximations about the physics of compact stars. While DM deposits its kinetic energy in the star quite quickly\, for appreciable annihilation heating to be achieved\ , capture and annihilation processes should reach a state of equilibrium. We also revisit the calculation of the capture-annihilation equilibrium ti mescales in neutron stars. For NSs\, we show that capture-annihilation equ ilibrium\, and hence maximal annihilation heating\, can be achieved withou t complete thermalization of the captured dark matter for all types of dar k matter - baryon interactions.

This includes cases where the sc attering or annihilation cross sections are momentum or velocity suppresse d in the non-relativistic limit. For scattering cross sections that satura te the capture rate\, we find that capture-annihilation equilibrium is typ ically reached on a timescale of less than a year for vector interactions and 10 thousand years for scalar interactions. For fermionic non-annihilat ing heavy DM\, we also revisit black hole (BH) formation\, accretion\, and evaporation. We find that previous results on the DM-nucleon scattering c ross section for a NS to be destructed by a BH from accumulated DM can be relaxed by a few orders of magnitude.

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