Browsing by Author "Eufrasio, Rafael"
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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 The Stellar Age Dependence of X-ray Emission from Normal Star-Forming Galaxies in the GOODS Fields(2021-12-20) Gilbertson, Woodrow; Lehmer, Bret; Doore, Keith; Eufrasio, Rafael; Basu-Zych, Antara; Brandt, William; Fragos, Tassos; Garofali, Kristen; Kovlakas, Konstantinos; Luo, Bin; Tozzi, Paolo; Vito, Fabio; Williams, Benjamin F.; Xue, YongquanThe Chandra Deep Field-South and North surveys (CDFs) provide unique windows into the cosmic history of X-ray emission from normal (non-active) galaxies. Scaling relations of normal galaxy X-ray luminosity (Lₓ The Chandra Deep Field-South and North surveys (CDFs) provide unique windows into the cosmic history of X-ray emission from normal (non-active) galaxies. Scaling relations of normal galaxy X-ray luminosity (Lₓ) with star formation rate (SFR) and stellar mass (M⋆) have been used to show that the formation rates of lowmass and high-mass X-ray binaries (LMXBs and HMXBs, respectively) evolve with redshift across z ≈ 0–2 following LHMXB/SFR ∝ (1 + z) and Lₗₘₓ/M⋆ ∝ (1 + z) ²−³. However, these measurements alone do not directly reveal the physical mechanisms behind the redshift evolution of X-ray binaries (XRBs). We derive star-formation histories for a sample of 344 normal galaxies in the CDFs, using spectral energy distribution (SED) fitting of FUV-to-FIR photometric data, and construct a self-consistent, age-dependent model of the Xray emission from the galaxies. Our model quantifies how X-ray emission from hot gas and XRB populations vary as functions of host stellar-population age. We find that (1) the ratio Lₓ/M⋆ declines by a factor of ∼1000 from 0–10 Gyr and (2) the X-ray SED becomes harder with increasing age, consistent with a scenario in which the hot gas contribution to the X-ray SED declines quickly for ages above 10 Myr. When dividing our sample into subsets based on metallicity, we find some indication that Lₓ/M⋆ is elevated for low-metallicity galaxies, consistent with recent studies of X-ray scaling relations. However, additional statistical constraints are required to quantify both the age and metallicity dependence of X-ray emission from star-forming galaxies.The Chandra Deep Field-South and North surveys (CDFs) provide unique windows into the cosmic history of X-ray emission from normal (non-active) galaxies. Scaling relations of normal galaxy X-ray luminosity (Lₓ) with star formation rate (SFR) and stellar mass (M⋆) have been used to show that the formation rates of lowmass and high-mass X-ray binaries (LMXBs and HMXBs, respectively) evolve with redshift across z ≈ 0–2 following LHMXB/SFR ∝ (1 + z) and Lₗₘₓ/M⋆ ∝ (1 + z) ²−³. However, these measurements alone do not directly reveal the physical mechanisms behind the redshift evolution of X-ray binaries (XRBs). We derive star-formation histories for a sample of 344 normal galaxies in the CDFs, using spectral energy distribution (SED) fitting of FUV-to-FIR photometric data, and construct a self-consistent, age-dependent model of the Xray emission from the galaxies. Our model quantifies how X-ray emission from hot gas and XRB populations vary as functions of host stellar-population age. We find that (1) the ratio Lₓ/M⋆ declines by a factor of ∼1000 from 0–10 Gyr and (2) the X-ray SED becomes harder with increasing age, consistent with a scenario in which the hot gas contribution to the X-ray SED declines quickly for ages above 10 Myr. When dividing our sample into subsets based on metallicity, we find some indication that Lₓ/M⋆ is elevated for low-metallicity galaxies, consistent with recent studies of X-ray scaling relations. However, additional statistical constraints are required to quantify both the age and metallicity dependence of X-ray emission from star-forming galaxies.) with star formation rate (SFR) and stellar mass (M⋆) have been used to show that the formation rates of lowmass and high-mass X-ray binaries (LMXBs and HMXBs, respectively) evolve with redshift across z ≈ 0–2 following LHMXB/SFR ∝ (1 + z) and Lₗₘₓ/M⋆ ∝ (1 + z) ²−³. However, these measurements alone do not directly reveal the physical mechanisms behind the redshift evolution of X-ray binaries (XRBs). We derive star-formation histories for a sample of 344 normal galaxies in the CDFs, using spectral energy distribution (SED) fitting of FUV-to-FIR photometric data, and construct a self-consistent, age-dependent model of the Xray emission from the galaxies. Our model quantifies how X-ray emission from hot gas and XRB populations vary as functions of host stellar-population age. We find that (1) the ratio Lₓ/M⋆ declines by a factor of ∼1000 from 0–10 Gyr and (2) the X-ray SED becomes harder with increasing age, consistent with a scenario in which the hot gas contribution to the X-ray SED declines quickly for ages above 10 Myr. When dividing our sample into subsets based on metallicity, we find some indication that Lₓ/M⋆ is elevated for low-metallicity galaxies, consistent with recent studies of X-ray scaling relations. However, additional statistical constraints are required to quantify both the age and metallicity dependence of X-ray emission from star-forming galaxies.