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.Reines, Amy E.Subject: search.filters.subject.black hole

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    An Outflow-driven Water Maser Associated with Positive Black Hole Feedback in the Dwarf Galaxy Henize 2–10
    (American Astronomical Society, 2024-07) Gim, Hansung B.; Reines, Amy E.; Momjian, Emmanuel; Darling, Jeremy
    Henize 2–10 is a dwarf galaxy experiencing positive black hole (BH) feedback from a radio-detected low-luminosity active galactic nucleus. Previous Green Bank Telescope (GBT) observations detected a H2O "kilomaser" in Henize 2–10, but the low angular resolution (33'') left the location and origin of the maser ambiguous. We present new Karl G. Jansky Very Large Array observations of the H2O maser line at 22.23508 GHz in Henize 2–10 with ∼2'' resolution. These observations reveal two maser sources distinct in position and velocity. The first maser source is spatially coincident with the known BH outflow and the region of triggered star formation ∼70 pc to the east. Combined with the broad width of the maser (W50 ∼ 66 km s−1), this confirms our hypothesis that part of the maser detected with the GBT is produced by the impact of the BH outflow shocking the dense molecular gas along the flow and at the interface of the eastern star-forming region. The second maser source lies to the southeast, far from the central BH, and has a narrow width (W50 ∼ 8 km s−1), suggesting a star formation–related origin. This work has revealed the nature of the H2O kilomaser in Henize 2–10 and illustrates the first known connection between outflow-driven H2O masers and positive BH feedback.
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    Wandering Black Hole Candidates in Dwarf Galaxies at VLBI Resolution
    (American Astronomical Society, 2022-07) Sargent, Andrew J.; Johnson, Megan C.; Reines, Amy E.; Secrest, Nathan J.; van der Horst, Alexander J.; Cigan, Phil J.; Darling, Jeremy; Greene, Jenny E.
    Thirteen dwarf galaxies have recently been found to host radio-selected accreting massive black hole (MBH) candidates, some of which are “wandering” in the outskirts of their hosts. We present 9 GHz Very Long Baseline Array (VLBA) observations of these sources at milliarcsecond resolution. Our observations have beam solid angles ∼104 times smaller than the previous Very Large Array (VLA) observations at 9 GHz, with comparable point-source sensitivities. We detect milliarcsecond-scale radio sources at the positions of the four VLA sources most distant from the photocenters of their associated dwarf galaxies. These sources have brightness temperatures of >106 K, consistent with active galactic nuclei (AGNs), but the significance of their preferential location at large distances (p-value = 0.0014) favors a background AGN interpretation. The VLBA nondetections toward the other nine galaxies indicate that the VLA sources are resolved out on scales of tens of milliarcseconds, requiring extended radio emission and lower brightness temperatures consistent with either star formation or radio lobes associated with AGN activity. We explore the star formation explanation by calculating the expected radio emission for these nine VLBA nondetections, finding that about five have VLA luminosities that are inconsistent with this scenario. Of the remaining four, two are associated with spectroscopically confirmed AGNs that are consistent with being located at their galaxy photocenters. There are therefore between five and seven wandering MBH candidates out of the 13 galaxies we observed, although we cannot rule out background AGNs for five of them with the data in hand.
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