Bulletin of the American Physical Society
20th Annual Meeting of the APS Northwest Section
Volume 64, Number 9
Thursday–Saturday, May 16–18, 2019; Western Washington University, Bellingham, Washington
Session C3: Astronomy and Cosmology |
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Chair: Kenneth Rines, Western Washington University Room: Viking Union 462B |
Friday, May 17, 2019 1:30PM - 2:00PM |
C3.00001: The role of morphological quenching in galaxy transformation. Invited Speaker: Alison Crocker Morphological quenching posits that galaxies might cease star formation based upon galaxy structural properties instead of any dramatic evolutionary processes such as galaxy-galaxy mergers or feedback from an active galactic nucleus. In particular, morphological quenching is invoked to explain the observed lower star formation efficiencies of cold-gas hosting, bulge-dominated galaxies. This talk will summarize the physics behind morphological quenching as well as evidence of morphological quenching of galaxies at both low and high redshift. [Preview Abstract] |
Friday, May 17, 2019 2:00PM - 2:30PM |
C3.00002: Searching for Lumbering Giants Invited Speaker: Jeffrey Hazboun Pulsar timing arrays will detect gravitational waves from the super-massive black hole binaries at the centers of merged galaxies in the next few years. The strongest signal is expected to be the unresolvable background from these binaries out to $z\approx 2$ ($8400 {\rm Mpc}$). Soon afterwards PTAs will be able to resolve single sources. The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) is an NSF funded Physics Frontiers Center monitoring over 70 millisecond pulsars for the signature of these gravitational waves. The most recent results from the NANOGrav 11-year and 12.5-year datasets, including limits on the stochastic background and single sources, will be presented. [Preview Abstract] |
Friday, May 17, 2019 2:30PM - 2:42PM |
C3.00003: Predictions of the canonical-mass neutron star radius based on chiral effective field theory Randy Millerson, Francesca Sammarruca Neutron stars are of great interest for studies in both astrophysics and nuclear physics. The central densities of these highly exotic objects can exceed several times normal nuclear density. In this work [1] we use a method for obtaining the radius of canonical-mass neutron stars (that is, stars with a mass of approximately 1.4 solar masses). We start with equations of state for beta-stable matter based on high-quality chiral two-nucleon forces and the leading chiral three-nucleon force up to moderately high density and then use polytropic extrapolation to extend the equation of state to higher densities. We find good agreement between our predictions and recent observational constraints, such as those from LIGO/Virgo measurements. [1] F. Sammarruca and Randy Millerson, J. Phys. G Nucl. Part. Phys. 46, 024001 (2019) [Preview Abstract] |
Friday, May 17, 2019 2:42PM - 2:54PM |
C3.00004: Dynamic Relativity: How Extra Gravity Halos are Projected from Galactic Cores John Huenefeld Adding an inward dynamic to General Relativity provides the basis for ongoing space-time contraction within a gravitational field. Unlike Hubble expansion, this contraction field is non linear with distance and is dependent on the amount of concentrated matter generating the field. Rather than assuming additional mass to boost the orbital velocity of stars around a galactic core, this field acts to boost the acceleration of Newtonian gravity to achieve rotation curves consistent with observation. Using only the normal matter within the galaxy, it can be shown how Extra Gravity Halos (EGH), are generated by galactic nuclei. As the search for dark matter particles continues to bear no fruit, it becomes ever more important to consider alternatives. The gravity scale factor, which falls easily from the math, has just the right shape with radius to replicate the effects of assumed dark matter distributions. Not only do these contraction fields explain galaxy rotation curves, they also explain the Bullet Cluster, and Ultra Diffuse galaxies composed of either nearly all or nearly no dark matter. [Preview Abstract] |
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