Description
Chair: Greg Marcel
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Tuomo Salmi (University of Helsinki)27/05/2026, 16:45Oral
Coherent radio emission is observed from a variety of compact astrophysical objects with relatively weak magnetic fields, including white dwarfs, millisecond pulsars, and possibly long-period radio transients and black hole magnetospheres. In such environments, the standard pair discharge mechanism—driven by synchrotron radiation and one-photon pair production—fails because the low magnetic...
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Mr Olavi Kiuru (University of Helsinki)27/05/2026, 17:00Oral
In the magnetospheres of magnetars, strongly magnetized neutron stars, the magnetic field can be tens of times the critical Schwinger field $B_Q = m^2/e \approx 4.41\cdot 10^{13}$ G. In this strong field regime quantum electrodynamics (QED) becomes nonlinear, which has profound effects on the plasma dynamics of the magnetosphere. Most notably the energies of electrons and positrons become...
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Vadzim Krautsou (University of Turku)27/05/2026, 17:15Oral
In this talk, I’ll present the results of a comprehensive, 3-year-long multiwavelength polarimetric campaign on the prototypical black hole X-ray binary Cygnus X-1, conducted between 2022 and 2024. Using data from the Imaging X-ray Polarimetry Explorer (IXPE), we measured X-ray polarization 13 times across both hard and soft spectral states. We found that the polarization degree in the hard...
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Anna Bobrikova (University of Turku)27/05/2026, 17:30Oral
Weakly magnetized neutron stars are among the brightest objects in the X-ray sky. Unlike pulsars, in these systems, magnetic field is not strong enough to affect the accretion flow, so the accreted matter falls directly onto the neutron star surface. The exact geometry of the accretion flow in these systems is still unknown, and until recently, we did not have an appropriate tool to study this...
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Alexander Salganik (University of Turku)27/05/2026, 17:45Oral
We report the first detection of X-ray polarization with the Imaging X-ray Polarimetry Explorer (IXPE) from the X-ray pulsar (XRP) 4U 1954+319. The source belongs to an extremely rare class of systems in which a slowly rotating neutron star accretes from the dense wind of a red supergiant companion. Coherent pulsations are detected at $P_{\rm spin}=5.49\pm0.05$ h, which is one of the longest...
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Sofia Forsblom (University of Turku)27/05/2026, 18:00Oral
Observations of accreting X-ray pulsars (XRPs) carried out by the Imaging X-ray Polarimetry Explorer (IXPE) have provided completely new insight into these fascinating objects, thanks to the indispensable information embedded in their linear X-ray polarization. X-ray polarimetry enables us to measure the polarization angle (PA) and degree (PD) as a function of pulse phase for XRPs, which...
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