Bulletin of the American Physical Society
APS April Meeting 2023
Volume 68, Number 6
Minneapolis, Minnesota (Apr 15-18)
Virtual (Apr 24-26); Time Zone: Central Time
Session QQ01: V: Medium: Cosmic Rays, AGN, & Galaxies |
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Sponsoring Units: DAP Chair: Tianqi Zhao, Ohio University (OU) Room: Virtual Room 1 |
Tuesday, April 25, 2023 12:00PM - 12:12PM |
QQ01.00001: Recent results from CALET on the International Space Station Nicholas W Cannady The Calorimetric Electron Telescope (CALET) is an astroparticle physics telescope deployed on the International Space Station (ISS) since August 2015. The primary instrument is a 30 radiation-length deep electromagnetic calorimeter sensitive to cosmic-ray electrons in the range from 1 GeV to above 10 TeV and cosmic-ray hadrons up to PeV total energies. We present here an overview of the results after 7 years of stable, continuous operation, focusing on results published in the past year. |
Tuesday, April 25, 2023 12:12PM - 12:24PM |
QQ01.00002: X-ray Coverage of the LSST Deep-Drilling Fields: Current XMM-Newton Results and STAR-X Future Prospects William N Brandt Cosmic X-ray surveys over the past two decades have played a critical role in transforming our understanding of growing supermassive black holes (SMBHs) in the distant universe. I will describe one key survey, recently completed, advancing this effort: the 13.1 deg2 XMM-SERVS survey. XMM-SERVS has successfully mapped three LSST Deep-Drilling Fields (DDFs) at 50 ks XMM-Newton depth, focusing on the SERVS areas of CDF-S, XMM-LSS, and ELAIS-S1. These fields have first-rate multiwavelength coverage already and are LSST/DES DDFs, MOONS/PFS massive spectroscopy fields, prime TolTEC/ALMA fields, and SDSS-V/4MOST multi-object reverberation-mapping fields. About 12,000 X-ray sources have been detected and characterized, the majority of which (86%) are active galactic nuclei (AGNs), and these are presently being studied. I will briefly summarize ongoing science investigations in these fields, including multiwavelength fitting of infrared-to-X-ray spectral energy distributions, identification of the most highly X-ray obscured AGNs, dwarf AGN studies, and combined radio/X-ray AGN investigations. I will also highlight how the proposed STAR-X MIDEX mission will obtain much more sensitive X-ray coverage of the LSST DDFs as it conducts its 12 deg2 Deep and 300 deg2 Medium-Deep time-domain surveys. STAR-X will detect about 74,000 X-ray sources in its planned Deep surveying of the DDFs and thereby illuminate the growth modes of the first SMBHs, obscured SMBH growth through the era of galaxy assembly, novel X-ray transients, high-redshift clusters, and protoclusters. |
Tuesday, April 25, 2023 12:24PM - 12:36PM |
QQ01.00003: Detection Advancement and Variability Modeling of Ultra-Fast Outflows to Constrain AGN Feedback Mechanisms Labani Mallick The discovery of energetic ultra-fast outflows (UFOs) in luminous active galactic nuclei (AGN) via the detection of highly blueshifted absorption lines in the X-ray count spectra is considered to provide the `feedback' mechanisms linking the central supermassive black holes with their host galaxies. To characterize UFOs, we traditionally perform photoionization modeling of the observed absorption lines using X-ray flux spectra. However, the detection significance of UFO features strongly depends on the model used for the continuum. To overcome this issue, we developed a variability technique for advancing the detection of UFOs and created physical models to fit variability spectra. Our variability method of UFO detection is fast and less biased by the continuum shape. The UFO features appear as positive 'spikes' since they respond rapidly to the central X-ray source and are more pronounced than in traditional flux spectra. By fitting a simple spline to the variability spectra of a sample of bright AGN, we detected several UFO spikes of velocity 0.1-0.3c, unlike the flux spectra, which did not always show strong UFO absorption lines. This coherent UFO variability gives us a powerful probe of outflows in a whole new dimension. We also created physical models to fit the variability spectra of the sample and confirmed the presence of wind absorption (e.g., FeXXV or FeXXVI) outflowing with velocities 0.1-0.3c. Our variability models can constrain parameters inaccessible through conventional flux spectroscopy, such as the correlations between the wind and the accretion disk and the response time of the gas. One of the most important applications of such methods/models would be on X-ray microcalorimeter data from XRISM and Athena, where we can separate different layers of absorption in the wind with distinct variability properties. |
Tuesday, April 25, 2023 12:36PM - 12:48PM |
QQ01.00004: Tidal Disruption Events of Stars by Intermediate-Mass Black Holes Fulya Kiroglu, Kyle Kremer, Fred Rasio, James Lombardi, Giacomo Fragione IMBHs may form in dense star clusters via the merger of stellar-mass black holes or the collapse of very massive stars. Within these dense environments, tidal disruption events (TDEs) of cluster stars by IMBHs are likely to produce electromagnetic signatures with a long-lived super-Eddington accretion phase. In this talk, I will present the outcomes of hydrodynamic calculations of TDEs of Main-Sequence stars by IMBHs. Depending upon the distance at the closest approach, these events can lead to a fully disrupted star or partially disrupted bound/unbound remnant. We find that stronger encounters lead to increased mass loss at the first pericenter passage, in many cases ejecting the partially disrupted star on an unbound orbit. For encounters that initially produce a bound system, with only partial stripping of the star, the fraction of mass stripped from the star increases with each subsequent pericenter passage and a stellar remnant of finite mass is ultimately ejected in all cases. We also find that the number of successive close passages before ejection decreases as we go from the stellar-mass black hole to the intermediate-mass black hole regime. For instance, after an initial encounter right at the classical tidal disruption limit, a 1M? star undergoes 16 (5) pericenter passages before ejection from a 10M? (100M?) black hole. Observations of consecutive electromagnetic flares from these repeated close passages could in principle be used to determine the mass of the black hole, thus possibly proving the existence of intermediate-mass black holes. |
Tuesday, April 25, 2023 12:48PM - 1:00PM |
QQ01.00005: Analysis of a Sample of Extreme High-Frequency Peaked BL Lac Objects with the HAWC Observatory Erica Heller, Hugo Ayala, Miguel A Mostafa Starting from a sample of extreme high-frequency-peaked BL Lac objects (EHBLs) analyzed by the MAGIC telescopes, we searched for very-high-energy (VHE) gamma-ray emission from these objects using the six-year data set from the HAWC Observatory. We established flux upper limits assuming extrapolated power laws for each source, and we will present the results of our search in the VHE range. |
Tuesday, April 25, 2023 1:00PM - 1:12PM |
QQ01.00006: Tau Appearance from High-Energy Neutrino Interactions Pavel Zhelnin, Carlos A Arguelles Delgado, Alfonso Garcia, Ibrahim Safa High-energy muon and electron neutrinos yield a non-negligible flux of tau neutrinos as they propagate through Earth. In this talk, the impact of this additional component in the PeV and EeV energy regimes is addressed for the first time. This contribution is predicted to be significantly larger than the atmospheric background above 300 TeV, and so effects future cosmic tau neutrino flux discovery in current/future neutrino telescopes. Further we demonstrate that Earth-skimming neutrino experiments, designed to observe tau neutrinos, will be sensitive to cosmogenic neutrinos, even in extreme scenarios without a primary tau neutrino component. |
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