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:20260725T153741Z UID:4c9879fb-dee9-4f62-b3f8-387f509cb15d SEQUENCE:1 CREATED:20250925T091744Z DESCRIPTION: Compact stellar objects 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 transfers kinetic energy to the star during the collision. This together with further DM annihilation in the stellar inte rior can have various observational consequences such as the anomalous hea ting of old compact stars and compact star destruction for non-annihilatin g DM. We have improved former calculations of the capture and thermalizati on rates in both white dwarfs (WDs) and neutron stars (NSs)\, making littl e approximations about the physics of compact stars. While DM deposits its kinetic energy in the star quite quickly\, for appreciable annihilation h eating to be achieved\, capture and annihilation processes should reach a state of equilibrium. We also revisit the calculation of the capture-annih ilation equilibrium timescales in neutron stars. For NSs\, we show that ca pture-annihilation equilibrium\, and hence maximal annihilation heating\, can be achieved without complete thermalization of the captured dark matte r for all types of dark matter - baryon interactions. This includes cases where the scattering or annihilation cross sections are momentum or veloci ty suppressed in the non-relativistic limit. For scattering cross sections that saturate the capture rate\, we find that capture-annihilation equili brium is typically reached on a timescale of less than a year for vector i nteractions and 10 thousand years for scalar interactions. For fermionic n on-annihilating heavy DM\, we also revisit black hole (BH) formation\, acc retion\, and evaporation. We find that previous results on the DM-nucleon scattering cross section for a NS to be destructed by a BH from accumulate d DM can be relaxed by a few orders of magnitude. LAST-MODIFIED:20250925T091744Z LOCATION:DF Seminar Room (2-8.3)\, 2nd floor of Physics Building URL:http://df.vps.tecnico.ulisboa.pt/en/events/dark-matter-in-compact-star s/ X-ALT-DESC;FMTTYPE=text/html:

Compact stellar ob jects 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 tran sfers kinetic energy to the star during the collision. This together with further DM annihilation in the stellar interior can have various observati onal consequences such as the anomalous heating of old compact stars and c ompact star destruction for non-annihilating DM.

We have improve d former calculations of the capture and thermalization rates in both whit e dwarfs (WDs) and neutron stars (NSs)\, making little approximations abou t the physics of compact stars. While DM deposits its kinetic energy in th e 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 t imescales in neutron stars. For NSs\, we show that capture-annihilation eq uilibrium\, and hence maximal annihilation heating\, can be achieved witho ut complete thermalization of the captured dark matter for all types of da rk matter - baryon interactions.

This includes cases where the s cattering or annihilation cross sections are momentum or velocity suppress ed in the non-relativistic limit. For scattering cross sections that satur ate the capture rate\, we find that capture-annihilation equilibrium is ty pically reached on a timescale of less than a year for vector interactions and 10 thousand years for scalar interactions. For fermionic non-annihila ting heavy DM\, we also revisit black hole (BH) formation\, accretion\, an d evaporation. We find that previous results on the DM-nucleon scattering cross 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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