Publications by authors named "Laura Di Gesu"

Article Synopsis
  • The Milky Way's center contains a dormant black hole, Sagittarius A (Sgr A), with a mass of about 4 million solar masses and low luminosity compared to active galactic nuclei.
  • Researchers have studied X-ray reflections from surrounding dense gas to investigate Sgr A's past activity, suggesting it flared up significantly in the past.
  • Observations from the Imaging X-ray Polarimetry Explorer revealed a 31% polarization degree in X-rays, indicating Sgr A was much more active around 200 years ago, with luminosity similar to that of a Seyfert galaxy.
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Pulsar wind nebulae are formed when outflows of relativistic electrons and positrons hit the surrounding supernova remnant or interstellar medium at a shock front. The Vela pulsar wind nebula is powered by a young pulsar (B0833-45, aged 11,000 years) and located inside an extended structure called Vela X, which is itself inside the supernova remnant. Previous X-ray observations revealed two prominent arcs that are bisected by a jet and counter jet.

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Most of the light from blazars, active galactic nuclei with jets of magnetized plasma that point nearly along the line of sight, is produced by high-energy particles, up to around 1 TeV. Although the jets are known to be ultimately powered by a supermassive black hole, how the particles are accelerated to such high energies has been an unanswered question. The process must be related to the magnetic field, which can be probed by observations of the polarization of light from the jets.

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A black hole x-ray binary (XRB) system forms when gas is stripped from a normal star and accretes onto a black hole, which heats the gas sufficiently to emit x-rays. We report a polarimetric observation of the XRB Cygnus X-1 using the Imaging X-ray Polarimetry Explorer. The electric field position angle aligns with the outflowing jet, indicating that the jet is launched from the inner x-ray-emitting region.

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Magnetars are neutron stars with ultrastrong magnetic fields, which can be observed in x-rays. Polarization measurements could provide information on their magnetic fields and surface properties. We observed polarized x-rays from the magnetar 4U 0142+61 using the Imaging X-ray Polarimetry Explorer and found a linear polarization degree of 13.

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Synopsis of recent research by authors named "Laura Di Gesu"

  • - Laura Di Gesu's recent research primarily focuses on the polarization of X-rays from various astronomical phenomena, providing insights into high-energy processes and the geometries of cosmic structures.
  • - Key findings include evidence of past flaring activity in the black hole Sagittarius A (Sgr A) and the identification of polarized X-rays from magnetars, which help illuminate their magnetic field properties.
  • - Her work also examines particle acceleration in blazar jets and the geometry of the disk-jet system in black hole X-ray binary Cygnus X-1, highlighting the role of magnetic fields in these extreme environments.

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