Browsing by Author "Zajczyk, Anna"
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Item An Analysis of the North Polar Spur Using HaloSat(IOP, 2020-11-20) LaRocca, Daniel M.; Kaaret, Philip; Kuntz, K. D.; Hodges-Kluck, Edmund; Zajczyk, Anna; Bluem, Jesse; Ringuette, Rebecca; Jahoda, Keith M.We present HaloSat X-ray observations of the entirety of the bright X-ray emitting feature known as the North Polar Spur (NPS). The large field of view of HaloSat enabled coverage of the entire bright NPS in only 14 fields, which were each observed for ≈30,000 s. We find that the NPS fields are distinct in both brightness and spectral shape from the surrounding halo fields. We fit the NPS as two thermal components in ionization equilibrium with temperatures kT keV cool » 0.087 and kT keV hot » 0.28 . We note a temperature gradient in the NPS hot component with an inner arc temperature warmer than the outer arc. The emission measures we find for the cool component of the NPS is a factor of 3–5 greater than that of the hot component, which suggests that the bulk of the NPS material is in the ≈0.1 keV component. We evaluate distance estimates of 0.4 and 8.0 kpc for the NPS. Our findings suggest a preference for a distant NPS with an energy of ≈ 6 × 10⁵⁴ erg, an age of ≈ 10 Myr, and pressures consistent with a 10μG magnetic field associated with the Fermi bubbles. The electron density ≈10 × 10⁻³ cm⁻³ is consistent with estimates for the shock region surrounding a Galactic-scale event.Item Development of the ComPair gamma-ray telescope prototype(SPIE, 2022-08-31) Shy, Daniel; Kierans, Carolyn; Cannady, Nicholas; Caputo, Regina; Schoenwald, Adam J.; Zajczyk, Anna; et alThere is a growing interest in the science uniquely enabled by observations in the MeV range, particularly in light of multi-messenger astrophysics. The Compton Pair (ComPair) telescope, a prototype of the AMEGO Probe-class concept, consists of four subsystems that together detect and characterize gamma rays in the MeV regime. A double-sided strip silicon Tracker gives a precise measure of the first Compton scatter interaction and tracks pair-conversion products. A novel cadmium zinc telluride (CZT) detector with excellent position and energy resolution beneath the Tracker detects the Compton-scattered photons. A thick cesium iodide (CsI) calorimeter contains the high-energy Compton and pair events. The instrument is surrounded by a plastic anticoincidence (ACD) detector to veto the cosmic-ray background. In this work, we will give an overview of the science motivation and a description of the prototype development and performance.Item Double-Sided Silicon Strip Detectors for Next-Generation Gamma-ray Telescopes(American Physical Society) Cannady, Nick; Krizmanic, John; Ojha, Roopesh; Zajczyk, Anna; et alThis Letter of Intent describes the motivation for the continued development of double-sided silicon strip detectors (DSSDs). Silicon detectors have a long history of groundbreaking measurements in astroparticle physics, and in the new era of multimessanger astrophysics, they will continue to be instrumental through refinement in the MeV regime. DSSDs provide high resolution measurements of the position and energy of photon and charged particle interactions necessary to enable an MeV gamma-ray mission and bolster the advancement of mulitmessenger astrophysics.Item Widespread Detection of Two Components in the Hot Circumgalactic Medium of the Milky Way(2022-08-04) Bluem, Jesse; Kaaret, Philip; Kuntz, K. D.; Jahoda, Keith M.; Koutroumpa, Dimitra; Hodges-Kluck, Edmund J.; Fuller, Chase A.; LaRocca, Daniel M.; Zajczyk, AnnaSurrounding the Milky Way (MW) is the circumgalactic medium (CGM), an extended reservoir of hot gas that has significant implications for the evolution of the MW. We used the HaloSat all-sky survey to study the CGM's soft X-ray emission in order to better define its distribution and structure. We extend a previous HaloSat study of the southern CGM (Galactic latitude b < -30 deg) to include the northern CGM (b > 30 deg) and find evidence that at least two hot gas model components at different temperatures are required to produce the observed emission. The cooler component has a typical temperature of kT ~ 0.18 keV, while the hotter component has a typical temperature of kT ~ 0.7 keV. The emission measure in both the warm and hot components has a wide range (~ 0.005 - 0.03, ~ 0.0005 - 0.004 cm-6 pc respectively), indicating that the CGM is clumpy. A patch of relatively consistent CGM was found in the north, allowing for the CGM spectrum to be studied in finer detail using a stacked spectrum. The stacked spectrum is well described with a model including two hot gas components at temperatures of kT = 0.166 +/- 0.005 keV and kT = 0.69 +0.04 -0.05 keV. As an alternative to adding a hot component, a neon-enhanced single-temperature model of the CGM was also tested and found to have worse fit statistics and poor residuals.