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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
NASA NTRS1996

Visual Utility for the Localization of Corona-Accelerated Nuclei

There is considerable controversy as to whether flares are the sole producers of energetic protons or whether coronal mass ejections play a central role. We note that the system described in this paper is presently capable of computing flux predictions only for protons associated with solar-flare activity.

flares↗
NASA NTRS2024

X-Ray Polarization Measurement of the Gold Standard of Radio-Quiet Active Galactic Nuclei: NGC 1068

Context.NGC 1068 is the most observed radio-quiet active galactic nucleus (AGN) in polarimetry, yet its high-energy polarization has never been probed before due to a lack of dedicated polarimeters.Aims.Using the first X-ray polarimeter sensitive enough to measure the polarization of AGNs, we want to probe the orientation and geometric arrangement of (sub)parsec-scale matter around the X-ray source. Methods. We used the Imaging X-ray Polarimetry Explorer (IXPE) satellite to measure, for the first time, the 2–8 keV polarization of NGC 1068.We pointed IXPE at the target for a net exposure time of 1.15 Ms, in addition to using two Chandra snapshots of∼10 ks each in order to account for the potential impact of several ultraluminous X-ray sources (ULXs) within IXPE’s field of view. Results. We measured a 2–8 keV polarization degree of 12.4%±3.6% and an electric vector polarization angle of 101◦±8◦at a 68% confidence level. If we exclude the spectral region containing bright Fe K lines and other soft X-ray lines where depolarization occurs, the polarization fraction rises to 21.3%±6.7% in the 3.5–6.0 keV band, with a similar polarization angle. The observed polarization angle is found to be perpendicular to the parsec-scale radio jet. Using a combined Chandra and IXPE analysis plus multiwavelength constraints, we estimated that the circum nuclear“torus” may sustain a half-opening angle of 50–55◦(from the vertical axis of the system). Conclusions. Thanks to IXPE, we have measured the X-ray polarization of NGC 1068 and found comparable results, both in terms of the polarization angle orientation with respect to the radio jet and the torus half-opening angle, to the X-ray polarimetric measurement achieved for the other archetypal Compton-thick AGN: the Circinus galaxy. Probing the geometric arrangement of parsec-scale matter in extragalactic objects is now feasible thanks to X-ray polarimetry

active galaxies↗