Physics

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The Physics department is committed to education and research in physics, the study of the fundamental universal laws that govern the behavior of matter and energy, and the exploration of the consequences and applications of those laws. Our department is widely known for its excellent teaching and student mentoring. Our department plays an important role in the university’s Core Curriculum. We have strong academic programs with several options for undergraduate physics majors, leading to the B.S. degree, as well as graduate curricula leading to the M.S. and Ph.D. degrees. Our research groups span a variety of fields within physics. Our principal concentrations are in Astrophysics, Relativity, Gravitation and Cosmology, Condensed Matter Physics, Lasers and Optics, Physics Education, Solar Physics, and the Space Science and Engineering Lab.

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Author: search.filters.author.Hickox, Ryan C.Subject: search.filters.subject.Dwarf Galaxy

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    NuSTAR Observations of a Heavily X-Ray-obscured AGN in the Dwarf Galaxy J144013+024744
    (American Astronomical Society, 2023-01) Ansh, Shrey; Chen, Chien-Ting J.; Brandt, W. N.; Hood, Carol E.; Kammoun, E. S.; Lansbury, G.; Paltani, Stéphane; Reines, Amy E.; Ricci, C.; Swartz, Douglas A.; Trump, Jonathan R.; Vito, F.; Hickox, Ryan C.
    We present a multiwavelength analysis of the dwarf Seyfert 2 galaxy J144013+024744, a candidate obscured active galactic nucleus (AGN) thought to be powered by an intermediate-mass black hole (IMBH, M • ≈ 104−106 M ⊙) of mass M • ∼ 105.2 M ⊙. To study its X-ray properties, we targeted J144013+024744 with NuSTAR for ≈100 ks. The X-ray spectrum was fitted with an absorbed power law, Pexmon, and a physical model (RXTorus). A Bayesian X-ray analysis was performed to estimate the posteriors. The phenomenological and the physical models suggest the AGN to be heavily obscured by a column density of N H = (3.4–7.0) × 1023 cm−2. In particular, the RXTorus model with a subsolar metallicity suggests the obscuring column to be almost Compton-thick. We compared the 2–10 keV intrinsic X-ray luminosity with the inferred X-ray luminosities based on empirical scaling relations for unobscured AGNs using L [Oiv] 25.89 μm, L [Oiii] λ5007, and L 6μm and found that the high-excitation [Oiv] line provides a better estimate of the intrinsic 2–10 keV X-ray luminosity ( L 2 – 10 int ∼ 10 41.41 erg s−1). Our results suggest that J144013+024744 is the first type 2 dwarf galaxy that shows X-ray spectroscopic evidence for obscuration. The column density that we estimated is among the highest measured to date for IMBH-powered AGNs, implying that a typical AGN torus geometry might extend to the low-mass end. This work has implications for constraining the BH occupation fraction in dwarf galaxies using X-ray observations.
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