How strong magnetic fields shape jets: insights from ALMA observations of a transitional millisecond pulsar

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The process of accretion onto compact objects and its role in the production of relativistic, collimated jets remains a major open question in astronomy. Transitional millisecond pulsars (tMSPs) provide a rare opportunity to study the formation of relativistic jets in neutron stars that experience low-level accretion yet possess strong magnetic fields. By analyzing archival multiwavelength…

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PSR J2055: a gentle spider

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Spiders are millisecond pulsars in compact binary systems. The variable optical emission from their companion stars reveals how the relativistic pulsar wind irradiates the companion and interacts with its outflowing matter. By modelling this optical emission, we can precisely constrain the fundamental parameters of spiders and find super-massive neutron stars, which are usually hosted in…

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Investigating cannibalistic millisecond pulsar binaries using MESA: new constraints from pulsar spin and mass evolution

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Compact millisecond pulsar (MSP) binaries are crucial for understanding the formation of massive pulsars and the boundary between neutron stars (NSs) and black holes (BHs). Often referred to as “spiders” due to the cannibalistic interaction between the pulsar and its companion, these systems are broadly categorized into redbacks (RBs, with companion masses between 0.1 and…

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COBIPULSE: the discovery of three new spider pulsars

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Compact binary millisecond pulsars, also known as “spiders”, host the most massive neutron stars ever observed to date. Expanding the currently known spider population holds the key to determining the maximum neutron star mass, which has crucial implications for astrophysics, nuclear physics and gravitational wave astronomy. Searching for the variable optical emission of their companions…

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“The invisible black widow” is changing our view on the structure of ionized matter in our Galaxy

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Pulsar radio emission, associated with rapidly spinning neutron stars, enables the estimation of their distances in the Galaxy through dispersion measure (DM). The DM quantifies the dispersive delay experienced by electromagnetic radiation as it traverses ionized matter, such as the interstellar medium (ISM). By measuring this delay across a range of frequencies, astronomers can obtain…

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Arachnid astrometry: Charting the distances to celestial spiders with Gaia

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Compact binary millisecond pulsars are captivating celestial objects comprised of fast-spinning neutron stars orbiting closely with lighter companion stars. Neutron stars are ultra-dense remnants of massive stars resulting from supernova explosions at the culmination of their lifecycles. These binary pulsars exhibit distinct behaviors due to intense gravitational interactions between the stars. Pulsars emit particle “winds”…

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The power of irradiation: How vicious can spider pulsars be?

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We present the first multi-band optical light curves of PSR J1622-0315, among the most compact known redback binary millisecond pulsars, with an orbital period Porb=3.9 h. We find a flux modulation with two maxima per orbital cycle and a peak-to-peak amplitude of about 0.3 mag, which we attribute to the ellipsoidal shape of the tidally distorted companion star. The optical colours imply a late-F to early-G spectral type companion and do not show any detectable temperature changes along the orbit. This suggests that the irradiation of the star’s inner face by the pulsar wind is unexpectedly missing despite its short orbital period.

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