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PRODID:www-nat-fau-eu//Events//EN
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SUMMARY:Physikalisches Kolloquium: Dr. Ekaterina Sokolova-Lapa - Magne
 tic fields shaping X-ray emission from accreting neutron stars: from v
 acuum polarisation to field geometry (Habilitationsvortrag)
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 00000010000000BEB060FEC9762C43927071AB32719CD2
DESCRIPTION:Titel: Magnetic fields shaping X-ray emission from accreti
 ng neutron stars: from vacuum polarisation to field geometry (Habilita
 tionsvortrag) Abstract: Neutron stars are remnants of stellar evolutio
 n that contain some of the densest stable matter and possess some of t
 he strongest magnetic fields in the Universe. In binary systems where 
 a neutron star accretes matter from a massive stellar companion\, its 
 magnetic field shapes the accretion process\, the deceleration of matt
 er and the emission mechanisms that produce X-rays. Near the surface\,
  competition between gas\, radiation and magnetic pressure creates com
 plex flow dynamics\, with emission emerging from a compact hot spot or
  an extended accretion column. At typical surface field strengths of h
 undreds of millions of Tesla\, the polarised quantum-electrodynamic (Q
 ED) vacuum can further modify matter-radiation interactions\, affectin
 g X-ray formation and even plasma dynamics. The origin of the X-rays r
 emains debated: they may form mainly through thermal Comptonization in
  a decelerated region or be reprocessed by bulk Comptonization in the 
 accretion flow\, a mechanism that also has implications for how the ma
 tter slows down. In this talk\, I will present a new approach to testi
 ng these scenarios through radiation beaming and cyclotron lines &#821
 2\; the absorption features seen in X-ray spectra. I will show how mag
 netised plasma and the QED vacuum shape these angle-dependent signatur
 es and the polarisation of the radiation. Combined with gravitational 
 light bending and neutron star rotation\, the signatures offer a way t
 o infer the large-scale magnetic field and spin orientation\, which ca
 n constrain the history of mass transfer and binary evolution. Polaris
 ation offers a further test: vacuum-plasma interplay can help explain 
 the unexpectedly low linear polarisation and its complex variation wit
 h energy and rotational phase found in recent observations. Future X-r
 ay missions promise higher-resolution spectra and mo
DTSTART:20261104T110000Z
DTEND:20261104T120000Z
LOCATION:Hörsaal H\, Staudtstr. 5\, 91058 Erlangen
DTSTAMP:20261016T064426Z
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