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Astronomy Colloquium
X-Ray Spectroscopic Insights Into the Microphysics of Collisionless Shocks
Date: Thursday, February 8th
Time: 3:30 pm - 4:30 pm
Place: 4421 Sterling Hall
Speaker: Ehud Behar, Technion
Abstract: The theory of collisionless shocks is well established and explains a multitude of astrophysical phenomena, while their microphysics is extremely difficult to probe with observations.
Narrow radiative recombination continua are the smoking gun of highly ionized species recombining with cold (kT ~ eV) electrons.
They are naturally observed in photo-ionized plasmas of active galaxies and X-Ray binaries, but what are they doing in hot (kT ~ keV) shocked plasmas, such as those observed in colliding wind binaries, supernova remnants, planetary nebulae, and novae?
The talk will present line-resolved X-ray spectra of these sources, the highlight of which will be spectacular XMM-Newton and Chandra X-ray observations of the 2020 nova YZ Ret.
The data provide a unique insight into the microphysics of shocked gases that no other measurement can, delivering unambiguous evidence for hot shocked gas directly mixing with cold electrons and neutral atoms, likely right around the shock front.
Host: Ke Zhang
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