Bulletin of the American Physical Society
APS April Meeting 2019
Volume 64, Number 3
Saturday–Tuesday, April 13–16, 2019; Denver, Colorado
Session B10: Dark Matter Astrophysics |
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Sponsoring Units: DAP Room: Sheraton Governor's Square 12 |
Saturday, April 13, 2019 10:45AM - 10:57AM |
B10.00001: Searching for Gamma-ray Spectral Lines in Dwarf Galaxies with HAWC Andrea Albert Observational evidence strongly suggests the majority of matter in the Universe is non-baryonic dark matter. Several models suggest dark matter is a particle, yet the particle nature of dark matter is still unknown. In several theories dark matter annihilation or decay produces gamma rays. Specifically, if dark matter annihilates or decays directly into two gamma rays (or a gamma ray and a neutral particle like a Z boson), a monochromatic spectral line is created. At TeV energies, no other processes are expected to produce spectral lines, making this a very clean indirect dark matter search channel. With the development of event-by-event energy reconstruction, we can search for spectral lines with the High Altitude Water Cherenkov (HAWC) Observatory. HAWC is a wide field of view survey instrument located in central Mexico that observes gamma rays from hundreds of GeV to >100 TeV. We will present results from a recent search for spectral lines from local dark matter dominated dwarf galaxies. |
Saturday, April 13, 2019 10:57AM - 11:09AM |
B10.00002: Astrophysical Systematics on Anti-nuclei Cosmic-Rays and Dark Matter Ilias Cholis, Tim Linden, Dan Hooper Antimatter cosmic-rays are used to study high energy astrophysical phenomena in the Galaxy. Using the antiproton cosmic-ray measurements by the Alpha Magnetic Spectrometer (AMS) on board ISS, I will present work in search of unexpected sources of antiprotons. I will discuss the uncertainties related to the interstellar propagation of cosmic-rays, the antiproton production cross-section from inelastic cosmic-ray collisions the interstellar medium, as well as the uncertainties from the effects of the solar wind. At the GeV range there is an excess of cosmic-ray antiprotons that could be accounted for by a dark matter particle in the mass range of 50 to 90 GeV. Also I will discuss the prospects of detecting anti-deuterons and anti-Helium nuclei produced both from inelastic collisions of high energy cosmic-rays with the interstellar medium gas and from dark matter annihilations. Interestingly, under certain astrophysical assumptions AMS may detect cosmic-ray anti-deuterons and anti-Helium from annihilating dark matter particles.
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Saturday, April 13, 2019 11:09AM - 11:21AM |
B10.00003: Astrophysical signatures of caustic ring of dark matter Sankha Subhra Chakrabarty, Pierre Sikivie The caustic ring model is a proposal for full phase space distribution of cold dark matter in the galactic halo which predicts the existence of ring caustics in the galactic plane. Under self-similarity, the radius of a caustic ring increases on cosmological time scales. We have studied the effects of a caustic ring on the stars and interstellar gas as the caustic sweeps through the stellar disk. We have found that a stellar orbit is strongly perturbed by the gravitational field of a nearby caustic. Simulating the dynamics of half a million stars under the influence of each caustic ring, we have predicted the relative over-densities of the stars to be approximately 120, 45, 30 and 15% near the 2nd, 3rd, 4th and 5th caustic rings. We have also determined the density profile of interstellar gas near each caustic ring. |
Saturday, April 13, 2019 11:21AM - 11:33AM |
B10.00004: New Evidence for Caustic Rings based on GAIA and 3D Dustmap Yaqi Han, Pierre Sikivie, Sankha Subhra Chakrabarty The infall of cold dark matter produces discrete flows and caustic structures in the galactic halo. Under axial and reflection symmetry, and dominated by a net overall rotation, the caustic structure would take the shape of a ring with a ‘tricusp’ cross section. We present features found in the GAIA skymap and the 3D dustmap with Pan-STARRS 1 as possible evidence for such a caustic ring structure. We give an estimate of the location and dimensions of the ring and its implication on the local dark matter flow density and the velocity vector. |
Saturday, April 13, 2019 11:33AM - 11:45AM |
B10.00005: Accretion of Dissipative Dark Matter onto Active Galactic Nuclei Walter O Tangarife We examine the possibility that accretion of Dissipative Dark Matter (DDM) onto Active Galactic Nuclei (AGN) contributes to the growth rate of Super Massive Black Holes (SMBHs). Such a scenario could alleviate tension associated with anomalously large SMBHs measured at very early cosmic times, as well as observations that indicate that the growth of the most massive SMBHs occurs before z~6, with little growth at later times. These observations are not readily explained within standard AGN theory. We find a range in the parameter space of DDM models where we both expect efficient accretion to occur and which is consistent with observations of a large sample of measured SMBHs. When DDM accretion is included, the predicted evolution of this sample seems to be more consistent with assumptions regarding maximal BH seed masses and maximal AGN luminosities. |
Saturday, April 13, 2019 11:45AM - 11:57AM |
B10.00006: Dynamical analysis of the dark matter and black hole mass in the dwarf spheroidal LEO I MARIA JOSE BUSTAMANTE ROSELL, EVA NOYOLA, KARL GEBHARDT, MAXIMILIAN FABRICIUS, JENS THOMAS, XIMENA MAZZALAY, GREG ZEIMANN We take new central kinematic measurements of the Milky Way dwarf spheroidal Leo I, finding a steady rise in the velocity dispersion in the central 300”, suggesting the existence of a black hole. We revisit previously published data on the same central region and identify crowding effects, which lower the prior measured dispersions. Combining our measurements and those of the literature unaffected by crowding, we apply axisymmetric, orbit-based models to measure the stellar mass-to-light ratio, black hole mass and a cored-logarithmic dark halo. We use a few models that include possible tidal effects of the Milky Way, and find in all a consistent value for the mass of the black hole of 3.4±1.5×106 solar masses, with the no black-hole case excluded at high significance (7<Δχ2<13). The dark halo parameters are heavily affected by the tidal models though, with their circular velocities among 10 km/s to 60 km/s. If confirmed, a black hole of this mass, about 10% of the host mass, would a have a significant effect on dwarf galaxy formation and evolution. |
Saturday, April 13, 2019 11:57AM - 12:09PM |
B10.00007: Micro-X Sounding Rocket: 1st Flight Performance and Future Prospects Antonia Hubbard The Micro-X Microcalorimeter X-Ray Imaging Rocket is a sounding rocket mission that launched on July 22, 2018. This was the first operation of high resolution Transition Edge Sensors in space, opening up sensitivity to new physics. Micro-X is designed to observe Supernova Remnants and BSM X-ray interactions, like those proposed from keV-scale sterile neutrino dark matter. I will present the engineering results of the first flight, with special emphasis on the successful performance of the cryostat and electronics within the challenging conditions of a sounding rocket flight. While a rocket pointing error led to minimal time on-target, the science instrument operated as expected, and data from this flight will be used to establish background flux limits and as calibration data in preparation for future flights. The rocket will re-fly in the fall of 2019 to observe the CasA SNR, after which modifications will be made to the payload to optimize it for a keV dark matter search. |
Saturday, April 13, 2019 12:09PM - 12:21PM |
B10.00008: First Space Flight of TESs with the Micro-X Rocket: Performance and Projections David C Goldfinger Micro-X had its maiden flight in the summer of 2018, representing the first operation of Transition Edge Sensors in space. This rocket borne instrument uses these cryogenic microcalorimeters to perform imaging spectroscopy in the soft X-ray band. In this talk, we present the in-flight performance of these detectors. Additionally, the detector performance from that flight is compared to instrument projections for its science goals, including imaging observations of the Cassiopiea A supernova remnant and wide field of view observations of the Milky Way dark matter halo to search for keV scale decaying dark matter, such as a sterile neutrino. |
Saturday, April 13, 2019 12:21PM - 12:33PM |
B10.00009: In-flight Magnetic Field Environment for the Micro-X Sounding Rocket Renee E Manzagol-Harwood The Micro-X project is an X-ray sounding rocket payload that had its first flight on July 22, 2018 from the White Sands Missile Range in New Mexico. The flight’s aim was to operate a Transition Edge Sensor (TES) X-ray microcalorimeter array in space and take a high-resolution, imaged spectrum of the Cassiopeia A (Cas-A) supernova remnant. A failure in the rocket's Attitude Control System caused the payload to experience excessive spinning and not observe its target, Cas-A. The SQUID readout chain lost lock for part of the observation, which indicates that its operational parameters may have been changed by a new environmental factor. In this talk, I will investigate when the readout failed relative to the exposure of magnetic fields; I will present how the trajectory, pointing direction, and rotation of the tumbling payload was used to find the experienced magnetic field by the detector readout and how that impacted performance. |
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