Browsing by Author "Nynka, Melania"

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    G359.97-0.038: A HARD X-RAY FILAMENT ASSOCIATED WITH A SUPERNOVA SHELL–MOLECULAR CLOUD INTERACTION
    (2015) Nynka, Melania; Hailey, Charles J.; Zhang, Shuo; Morris, Mark M.; Zhao, Jun-Hui; Goss, Miller; Bauer, Franz Erik; Boggs, Stephen E.; Craig, William W.; Christensen, Finn E.; Gotthelf, Eric V.; Harrison, Fiona A.; Mori, Kaya; Perez, Kerstin M.; Stern, Daniel; Zhang, William W.
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    HARD X-RAY MORPHOLOGICAL AND SPECTRAL STUDIES OF THE GALACTIC CENTER MOLECULAR CLOUD SGR B2: CONSTRAINING PAST SGR A☆ FLARING ACTIVITY
    (2015) Zhang, Shuo; Hailey, Charles J.; Mori, Kaya; Clavel, Maica; Terrier, Regis; Ponti, Gabriele; Goldwurm, Andrea; Bauer, Franz E.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Harrison, Fiona A.; Hong, Jaesub; Nynka, Melania; Soldi, Simona; Stern, Daniel; Tomsick, John A.; Zhang, William W.
    In 2013, NuSTAR observed the Sgr B2 region and for the first time resolved its hard X-ray emission on subarcminute scales. Two prominent features are detected above 10 keV:. a newly emerging cloud, G0.66-0.13, and the central 90 '' radius region containing two compact cores, Sgr B2(M) and Sgr B2(N), surrounded by diffuse emission. It is inconclusive whether the remaining level of Sgr. B2 emission is still decreasing or has reached a constant background level. A decreasing X-ray emission can be best explained by the X-ray reflection nebula scenario, where the cloud reprocesses a past giant outburst from Sgr A(star). In the X-ray reflection nebula (XRN) scenario, the 3-79 keV Sgr. B2 spectrum allows us to self-consistently test the XRN model using both the Fe K alpha line and the continuum emission. The peak luminosity of the past Sgr A(star) outburst is constrained to L3-79keV similar to 5 x 10(38) ergs s(-1). A newly discovered cloud feature, G0.66-0.13, shows different timing variability. We suggest that it could be a molecular clump located in the Sgr B2 envelope reflecting the same Sgr A(star) outburst. In contrast, if the Sgr. B2 X-ray emission has reached a constant background level, it would imply an origin of low-energy cosmic-ray (CR) proton bombardment. In this scenario, from the NuSTAR measurements we infer a CR ion power of dW/dt = (1 - 4) x 10(39) erg s(-1) and a CR ionization rate of zeta(H) = (6 - 10) x 10(-15) H-1 s(-1). measurements can become powerful tools to constrain the GC CR population.
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    High-energy x-rays from j174545.5-285829, the cannonball: a candidate pulsar wind nebula associated with Sgr a east
    (2013) Nynka, Melania; Hailey, Charles J.; Mori, Kaya; Baganoff, Frederick K; Bauer, Franz Erik; Boggs, Steven E.; Craig, William W.; Christensen, Finn E.; Gotthelf, Eric V.; Harrison, Fiona A.
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    The high energy X-ray probe (HEX-P): Resolving the nature of Sgr A* flares, compact object binaries and diffuse X-ray emission in the Galactic center and beyond
    (2024) Mori, Kaya; Ponti, Gabriele; Bachetti, Matteo; Bodaghee, Arash; Grindlay, Jonathan; Hong, Jaesub; Krivonos, Roman; Kuznetsova, Ekaterina; Mandel, Shifra; Rodriguez, Antonio; Stel, Giovanni; Zhang, Shuo; Bao, Tong; Bauer, Franz; Clavel, Maica; Coughenour, Benjamin; Garcia, Javier A.; Gerber, Julian; Grefenstette, Brian; Jaodand, Amruta; Lehmer, Bret; Madsen, Kristin; Nynka, Melania; Predehl, Peter; Salcedo, Ciro; Stern, Daniel; Tomsick, John
    HEX-P is a probe-class mission concept that will combine high spatial resolution X-ray imaging (<10 '' FWHM) and broad spectral coverage (0.2-80 keV) with an effective area far superior to current facilities' (including XMM-Newton and NuSTAR). These capabilities will enable revolutionary new insights into a variety of important astrophysical problems. We present scientific objectives and simulations of HEX-P observations of the Galactic Center (GC) and Bulge. We demonstrate the unique and powerful capabilities of the HEX-P observatory for studying both X-ray point sources and diffuse X-ray emission. HEX-P will be uniquely equipped to explore a variety of major topics in Galactic astrophysics, allowing us to 1) investigate broad-band properties of X-ray flares emitted from the supermassive black hole (BH) at Sgr A* and probe the associated particle acceleration and emission mechanisms; 2) identify hard X-ray sources detected by NuSTAR and determine X-ray point source populations in different regions and luminosity ranges; 3) determine the distribution of compact object binaries in the nuclear star cluster and the composition of the Galactic Ridge X-ray emission; 4) identify X-ray transients and measure fundamental parameters such as black hole spin; 5) find hidden pulsars in the Galactic Center; 6) search for BH-OB binaries and hard X-ray flares from young stellar objects in young massive clusters; 7) measure white dwarf (WD) masses of magnetic CVs to deepen our understanding of CV evolution and the origin of white dwarf magnetic fields; 8) explore primary particle accelerators in the GC in synergy with future TeV and neutrino observatories; 9) map out cosmic-ray distributions by observing non-thermal X-ray filaments; 10) explore past X-ray outbursts from Sgr A* through X-ray reflection components from giant molecular clouds.