Browsing by Author "Corrales, Lia"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item AXIS Advanced X-ray Imaging Satellite(2019-03-11) Mushotzky, Richard F.; Aird, James; Barger, Amy J.; Cappelluti, Nico; Chartas, George; Corrales, Lia; Eufrasio, Rafael; Fabian, Andrew C.; Falcone, Abraham D.; Gallo, Elena; Gilli, Roberto; Grant, Catherine E.; Hardcastle, Martin; Hodges-Kluck, Edmund; Kara, Erin; Koss, Michael; Li, Hui; Lisse, Carey M.; Loewenstein, Michael; Markevitch, Maxim; Meyer, Eileen T.; Miller, Eric D.; Mulchaey, John; Petre, Robert; Ptak, Andrew J.; Reynolds, Christopher S.; Russell, Helen R.; Safi-Harb, Samar; Smith, Randall K.; Snios, Bradford; Tombesi, Francesco; Valencic, Lynne; Walker, Stephen A.; Williams, Brian J.; Winter, Lisa M.; Yamaguchi, Hiroya; Zhang, William W.Much of the baryonic matter in the Universe, including the most active and luminous sources, are best studied in the X-ray band. Key advances in X-ray optics and detectors have paved the way for the Advanced X-ray Imaging Satellite (AXIS), a Probe-class mission that is a major improvement over Chandra, which has generated a steady stream of important discoveries for the past 2 decades. AXIS can be launched in the late 2020s and will transform our understanding in several major areas of astrophysics, including the growth and fueling of supermassive black holes, galaxy formation and evolution, the microphysics of cosmic plasmas, the time-variable universe, and a wide variety of cutting-edge studies. Relative to Chandra, the AXIS PSF is nearly twice as sharp on-axis; its field of view for subarcsecond imaging 70 times larger by area; its effective area at 1 keV is 10 times larger. The low-Earth orbit ensures a low and stable detector background, resulting in 50 times greater sensitivity than Chandra for extended sources. AXIS has a rapid repointing response with operations similar to Swift, but is 100 times more sensitive for time-domain science. These capabilities open up a vast discovery space and complement the next generation of astronomical observatories. A high-spectral-resolution mission (Athena) operating at the same time as a high-angular-resolution mission (AXIS) greatly increases the range of scientific discovery. AXIS will use lightweight X-ray optics made of thin single-crystal silicon mirrors developed at NASA Goddard. The detector array builds on a long legacy of X-ray CCD and provides improved photon localization, much faster readout time, and broader energy band. The estimated mission costs are consistent with the $1B Probe mission cost guideline.Item Dust and gas absorption in the high mass X-ray binary IGR J16318−4848(EDP sciences, 2020-09-15) Ballhausen, Ralf; Lorenz, Maximilian; Fürst, Felix; Pottschmidt, Katja; Corrales, Lia; Tomsick, John A.; Kühnel, Matthias Bissinger né; Kretschmar, Peter; Kallman, Timothy R.; Grinberg, Victoria; Hell, Natalie; Psadaraki, Ioanna; Rogantini, Daniele; Wilms, JörnContext. With an absorption column density on the order of 1024 cm−2, IGR J16318−4848 is one of the most extreme cases of a highly obscured high mass X-ray binary. In addition to the overall continuum absorption, the source spectrum exhibits a strong iron and nickel fluorescence line complex at 6.4 keV. Previous empirical modeling of these features and comparison with radiative transfer simulations raised questions about the structure and covering fraction of the absorber and the profile of the fluorescence lines. Aims. We aim at a self-consistent description of the continuum absorption, the absorption edges, and the fluorescence lines to constrain the properties of the absorbing material, such as ionization structure and geometry. We further investigate the effects of dust absorption on the observed spectra and the possibility of fluorescence emission from dust grains. Methods. We used XMM-Newton and NuSTAR spectra to first empirically constrain the incident continuum and fluorescence lines. Next we used XSTAR to construct a customized photoionization model where we vary the ionization parameter, column density, and covering fraction. In the third step we modeled the absorption and fluorescence in a dusty olivine absorber and employed both a simple analytical model for the fluorescence line emission and a Monte Carlo simulation of radiative transfer that generates line fluxes, which are very close to the observational data. Results. Our empirical spectral modeling is in agreement with previous works. Our second model, the single gas absorber does not describe the observational data. In particular, irrespective of the ionization state or column density of the absorber, a much higher covering fraction than previously estimated is needed to produce the strong fluorescence lines and the large continuum absorption. A dusty, spherical absorber (modeled as consisting of olivine dust, although the nature of dust cannot be constrained) is able to produce the observed continuum absorption and edges. Conclusions. A dense, dusty absorber in the direct vicinity of the source consisting of dust offers a consistent description of both the strong continuum absorption and the strong emission features in the X-ray spectrum of IGR J16318−4848. In particular, for low optical depth of individual grains, which is the case for typical volume densities and grain size distribution models, the dust will contribute significantly to the fluorescence emission.Item Leveraging High Resolution Spectroscopy to Understand the Disk and Relativistic Iron Line of Cygnus X-1Nowak, Michael A.; Wilms, Jörn; Pottschmidt, Katja; Grinberg, Victoria; Schulz, Norbert; Corrales, Lia