Astrophysics and Astronomy Commons^™

Evolution Of A Relativistic Electron Beam For Tracing Magnetospheric Field Lines, Andrew T. Powis, Peter Porazik, Michael Greklek-Mckeon, Kailas Amin, David Shaw, Igor D. Kaganovich, Jay R. Johnson, Ennio Sanchez

Faculty Publications

Tracing magnetic field-lines of the Earth's magnetosphere using beams of relativistic electrons will open up new insights into space weather and magnetospheric physics. Analytic models and a single-particle-motion code were used to explore the dynamics of an electron beam emitted from an orbiting satellite and propagating until impact with the Earth. The impact location of the beam on the upper atmosphere is strongly influenced by magnetospheric conditions, shifting up to several degrees in latitude between different phases of a simulated storm. The beam density cross-section evolves due to cyclotron motion of the beam centroid and oscillations of the beam envelope. …

Spatially Resolved Stellar Kinematics Of The Ultra-Diffuse Galaxy Dragonfly 44. Ii. Constraints On Fuzzy Dark Matter, Asher Wasserman, Pieter Van Dokkum, Aaron Romanowsky, Jean Brodie, Shany Danieli, Duncan Forbes, Roberto Abraham, Christopher Martin, Matt Matuszewski, Alexa Villaume, John Tamanas, Stefano Profumo

Faculty Publications

Given the absence of directly detected dark matter (DM) as weakly interacting massive particles, there is strong interest in the possibility that DM is an ultralight scalar field, here denoted as "fuzzy" DM. Ultra-diffuse galaxies, with the sizes of giant galaxies and the luminosities of dwarf galaxies, have a wide range of DM halo masses, thus providing new opportunities for exploring the connections between galaxies and their DM halos. Following up on new integral field unit spectroscopic observations and dynamics modeling of the DM-dominated ultra-diffuse galaxy Dragonfly 44 in the outskirts of the Coma Cluster, we present models of fuzzy …

Dark Matter And No Dark Matter: On The Halo Mass Of Ngc 1052, Duncan Forbes, Adebusola Alabi, Jean Brodie, Aaron Romanowsky

Faculty Publications

The NGC 1052 group, and in particular the discovery of two ultra-diffuse galaxies with very low internal velocity dispersions, has been the subject of much attention recently. Here we present radial velocities for a sample of 77 globular clusters associated with NGC 1052 obtained on the Keck telescope. Their mean velocity and velocity dispersion are consistent with that of the host galaxy. Using a simple tracer mass estimator, we infer the enclosed dynamical mass and dark matter fraction of NGC 1052. Extrapolating our measurements with a Navarro–Frenk–White (NFW) mass profile we infer a total halo mass of 6.2(±0.2) × 1012 …

Relativistic Particle Beams As A Resource To Solve Outstanding Problems In Space Physics, Ennio R. Sanchez, Andrew T. Powis, Igor D. Kaganovich, Robert Marshall, Peter Porazik, Jay R. Johnson, Michael Greklek-Mckeon, Kailas S. Amin, David Shaw, Micale Nicolls

Faculty Publications

The Sun's connection with the Earth's magnetic field and atmosphere is carried out through the exchange of electromagnetic and mass flux and is regulated by a complex interconnection of processes. During space weather events, solar flares, or fast streams of solar atmosphere strongly disturb the Earth's environment. Often the electric currents that connect the different parts of the Sun-Earth system become unstable and explosively release the stored electromagnetic energy in one of the more dramatic expressions of space weather—the geomagnetic storm and substorm. Some aspects of the magnetosphere-ionosphere connection that generates auroral arcs during space weather events are well-known. However, …

First Measurement Of Neutrino Oscillation Parameters Using Neutrinos And Antineutrinos By Nova, M. A. Acero, P. Adamson, L. Aliaga, T. Alion, V. Allakhverdian, S. Altakarli, N. Anfimov, A. Antoshkin, A. Aurisano, A. Back, C. Backhouse, M. Baird, N. Balashov, P. Baldi, B. A. Bambah, S. Bashar, K. Bays, S. Bending, R. Bernstein, V. Bhatnagar, Roberto Petti, Et. Al.

Faculty Publications

The NOvA experiment has seen a 4.4σ signal of ⊽ _e appearance in a 2 GeV⊽_μ beam at a distance of 810 km. Using 12.33×10²⁰ protons on target delivered to the Fermilab NuMI neutrino beamline, the experiment recorded 27 ⊽_μ→⊽_e candidates with a background of 10.3 and 102⊽_μ→⊽_μ candidates. This new antineutrino data are combined with neutrino data to measure the parameters |Δm ² ₃₂ | = 2.48 ^+0.11 _-0.06 x 10 ^-3 eV² / c⁴ and sin² θ₂₃ in the ranges …

Byu’S Connection To The Development Of Optical Memory: Innovation Takes Multiple Disciplines, Dan Broadbent

Faculty Publications

Optical memory technology is a way to store information using lasers and is used in videodiscs, CDs, DVDs, Blu-rays, M-Discs, etc. This technology was developed in Torrance, California in the 1970s by a team lead by Kent D. Broadbent, who graduated from BYU with a degree in Physics in 1949.

This display showcases the technology and those involved in its development.

Search For Intermediate Mass Black Hole Binaries In The First And Second Observing Runs Of The Advanced Ligo And Virgo Network, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration

Faculty Publications

Gravitational-wave astronomy has been firmly established with the detection of gravitational waves from the merger of ten stellar-mass binary black holes and a neutron star binary. This paper reports on the all-sky search for gravitational waves from intermediate mass black hole binaries in the first and second observing runs of the Advanced LIGO and Virgo network. The search uses three independent algorithms: two based on matched filtering of the data with waveform templates of gravitational-wave signals from compact binaries, and a third, model-independent algorithm that employs no signal model for the incoming signal. No intermediate mass black hole binary event …

Search For Eccentric Binary Black Hole Mergers With Advanced Ligo And Advanced Virgo During Their First And Second Observing Runs, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration

Faculty Publications

When formed through dynamical interactions, stellar-mass binary black holes (BBHs) may retain eccentric orbits (e > 0.1 at 10 Hz) detectable by ground-based gravitational-wave detectors. Eccentricity can therefore be used to differentiate dynamically formed binaries from isolated BBH mergers. Current template-based gravitational-wave searches do not use waveform models associated with eccentric orbits, rendering the search less efficient for eccentric binary systems. Here we present the results of a search for BBH mergers that inspiral in eccentric orbits using data from the first and second observing runs (O1 and O2) of Advanced LIGO and Advanced Virgo. We carried out the search …

Method For Approximating Field-Line Curves Using Ionospheric Observations Of Energy-Variable Electron Beams Launched From Satellites, Jake M. Willard, Jay R. Johnson, Jesse M. Snelling, Andrew T. Powis, Igor D, Kaganovich, Ennio R. Sanchez

Faculty Publications

Using electron beam accelerators attached to satellites in Earth orbit, it may be possible to measure arc length and curvature of field-lines in the inner magnetosphere if the accelerator is designed with the capability to vary the beam energy. In combination with additional information, these measurements would be very useful in modeling the magnetic field of the inner magnetosphere. For this purpose, a three step data assimilation modeling approach is discussed. The first step in the procedure would be to use prior information to obtain an initial forecast of the inner magnetosphere. Then, a family of curves would be defined …

Gwtc-1: A Gravitational-Wave Transient Catalog Of Compact Binary Mergers Observed By Ligo And Virgo During The First And Second Observing Runs, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration

Faculty Publications

We present the results from three gravitational-wave searches for coalescing compact binaries with component masses above 1  M_⊙ during the first and second observing runs of the advanced gravitational-wave detector network. During the first observing run (O1), from September 12, 2015 to January 19, 2016, gravitational waves from three binary black hole mergers were detected. The second observing run (O2), which ran from November 30, 2016 to August 25, 2017, saw the first detection of gravitational waves from a binary neutron star inspiral, in addition to the observation of gravitational waves from a total of seven binary black hole …

Search For The Isotropic Stochastic Background Using Data From Advanced Ligo's Second Observing Run, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration

Faculty Publications

The stochastic gravitational-wave background is a superposition of sources that are either too weak or too numerous to detect individually. In this study we present the results from a cross-correlation analysis on data from Advanced LIGO's second observing run (O2), which we combine with the results of the first observing run (O1). We do not find evidence for a stochastic background, so we place upper limits on the normalized energy density in gravitational waves at the 95% credible level of Ω_GW<6.0×10⁻⁸ for a frequency-independent (flat) background and Ω_GW<4.8×10⁻⁸ at 25 Hz for a background of compact …

Effect Of Field-Line Curvature On The Ionospheric Accessibility Of Relativistic Electron Beam Experiments, Jake M. Willard, Jay R. Johnson, Jesse M. Snelling, Andrew T. Powis, Igor D. Kaganovich, Ennio R, Sanchez

Faculty Publications

Magnetosphere-ionosphere coupling is a particularly important process that regulates and controls magnetospheric dynamics such as storms and substorms. However, in order to understand magnetosphere-ionosphere coupling it is necessary to understand how regions of the magnetosphere are connected to the ionosphere. It has been proposed that this connection may be established by firing electron beams from satellites that can reach an ionospheric footpoint creating detectable emissions. This type of experiment would greatly aid in identifying the relationship between convection processes in the magnetotail and the ionosphere and how the plasma sheet current layer evolves during the growth phase preceding substorms. For …

A Precise Determination Of (Anti)Neutrino Fluxes With (Anti)Neutrino-Hydrogen Interactions, H. Duyang, B. Guo, Roberto Petti

Faculty Publications

We present a novel method to accurately determine the flux of neutrinos and antineutrinos, one of the dominant systematic uncertainty affecting current and future long-baseline neutrino experiments, as well as precision neutrino scattering experiment. Using exclusive topologies in v(⊽)-hydrogen interactions, v_µp→µpπ ⁺, ⊽ _µp → µ ⁺pπ, and ⊽_µp → µ ⁺ n with small hadronic energy, we achieve an overall accuracy on the relative fluxes better than 1% in the energy range covering most of the available flux. Since we cannot rely on simulations nor model …

Formation Of Ultra-Diffuse Galaxies In The Field And In Galaxy Groups, Fangzhou Jiang, Avishai Dekel, Jonathan Freundlich, Aaron Romanowsky, Aaron Dutton, Andrea Macciò, Arianna Di Cintio

Faculty Publications

We study ultra-diffuse galaxies (UDGs) in zoom in cosmological simulations, seeking the origin of UDGs in the field versus galaxy groups. We find that while field UDGs arise from dwarfs in a characteristic mass range by multiple episodes of supernova feedback (Di Cintio et al.), group UDGs may also form by tidal puffing up and they become quiescent by ram-pressure stripping. The field and group UDGs share similar properties, independent of distance from the group centre. Their dark-matter haloes have ordinary spin parameters and centrally dominant dark-matter cores. Their stellar components tend to have a prolate shape with a Sérsic …

Electron Energization By Parallel Electric Fields In Poloidal Standing Waves, P. A. Damiano, Eun-Hwa Kim, Jay R. Johnson, P. Porazik

Faculty Publications

A hybrid gyrofluid‐kinetic electron model is adapted and used to simulate poloidal standing modes for different electron temperatures and azimuthal mode numbers. As in previous studies of toroidal standing modes, mirror force effects lead to increased parallel potential drops, monoenergetic electron energization, and wave energy dissipation as the ambient electron temperature is increased. A similar trend is also observed when the electron temperature is held fixed and the azimuthal mode number increased—owing to the narrowing of the azimuthal flux tube width, which necessitates more electron energization to carry the increased parallel current density. In both cases, the increase in electron …

Hyper Wide Field Imaging Of The Local Group Dwarf Irregular Galaxy Ic 1613: An Extended Component Of Metal-Poor Stars, Ragadeepika Pucha, Jeffrey Carlin, Beth Willman, Jay Strader, David Sand, Keith Bechtol, Jean Brodie, Denija Crnojević, Duncan Forbes, Christopher Garling, Jonathan Hargis, Annika Peter, Aaron Romanowsky

Faculty Publications

Stellar halos offer fossil evidence for hierarchical structure formation. Since halo assembly is predicted to be scale-free, stellar halos around low-mass galaxies constrain properties such as star formation in the accreted subhalos and the formation of dwarf galaxies. However, few observational searches for stellar halos in dwarfs exist. Here we present gi photometry of resolved stars in isolated Local Group dwarf irregular galaxy IC 1613 (M sstarf ~ 108 M ⊙). These Subaru/Hyper Suprime-Cam observations are the widest and deepest of IC 1613 to date. We measure surface density profiles of young main-sequence, intermediate to old red giant branch, and …

Spatially Resolved Stellar Kinematics Of The Ultra-Diffuse Galaxy Dragonfly 44. I. Observations, Kinematics, And Cold Dark Matter Halo Fits, Pieter Van Dokkum, Asher Wasserman, Shany Danieli, Roberto Abraham, Jean Brodie, Charlie Conroy, Duncan Forbes, Christopher Martin, Matt Matuszewski, Aaron Romanowsky, Alexa Villaume

Faculty Publications

We present spatially resolved stellar kinematics of the well-studied ultra-diffuse galaxy (UDG) Dragonfly 44, as determined from 25.3 hr of observations with the Keck Cosmic Web Imager. The luminosity-weighted dispersion within the half-light radius is ${\sigma }_{1/2}={33}_{-3}^{+3}$ km s−1, lower than what we had inferred before from a DEIMOS spectrum in the Hα region. There is no evidence for rotation, with ${V}_{\max }/\langle \sigma \rangle \lt 0.12$ (90% confidence) along the major axis, in possible conflict with models where UDGs are the high-spin tail of the normal dwarf galaxy distribution. The spatially averaged line profile is more peaked than a …

All-Sky Search For Continuous Gravitational Waves From Isolated Neutron Stars Using Advanced Ligo O2 Data, Tiffany Summerscales

Faculty Publications

We present results of an all-sky search for continuous gravitational waves (CWs), which can be produced by fast spinning neutron stars with an asymmetry around their rotation axis, using data from the second observing run of the Advanced LIGO detectors. Three different semicoherent methods are used to search in a gravitational-wave frequency band from 20 to 1922 Hz and a first frequency derivative from −1×10⁻⁸ to 2×10⁻⁹  Hz/s. None of these searches has found clear evidence for a CW signal, so upper limits on the gravitational-wave strain amplitude are calculated, which for this broad range in parameter space …

New Constraints On Early-Type Galaxy Assembly From Spectroscopic Metallicities Of Globular Clusters In M87, Alexa Villaume, Aaron Romanowsky, Jean Brodie, Jay Strader

Faculty Publications

The observed characteristics of globular cluster (GC) systems, such as metallicity distributions, are commonly used to place constraints on galaxy formation models. However, obtaining reliable metallicity values is particularly difficult because of our limited means to obtain high quality spectroscopy of extragalactic GCs. Often, "color–metallicity relations" are invoked to convert easier-to-obtain photometric measurements into metallicities, but there is no consensus on what form these relations should take. In this paper we make use of multiple photometric data sets and iron metallicity values derived from applying full-spectrum stellar population synthesis models to deep Keck/LRIS spectra of 177 GCs centrally located around …

Tests Of General Relativity With Gw170817, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration

Faculty Publications

The recent discovery by Advanced LIGO and Advanced Virgo of a gravitational wave signal from a binary neutron star inspiral has enabled tests of general relativity (GR) with this new type of source. This source, for the first time, permits tests of strong-field dynamics of compact binaries in the presence of matter. In this Letter, we place constraints on the dipole radiation and possible deviations from GR in the post-Newtonian coefficients that govern the inspiral regime. Bounds on modified dispersion of gravitational waves are obtained; in combination with information from the observed electromagnetic counterpart we can also constrain effects due …

Narrow-Band Search For Gravitational Waves From Known Pulsars Using The Second Ligo Observing Run, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration

Faculty Publications

Isolated spinning neutron stars, asymmetric with respect to their rotation axis, are expected to be sources of continuous gravitational waves. The most sensitive searches for these sources are based on accurate matched filtering techniques that assume the continuous wave to be phase locked with the pulsar beamed emission. While matched filtering maximizes the search sensitivity, a significant signal-to-noise ratio loss will happen in the case of a mismatch between the assumed and the true signal phase evolution. Narrow-band algorithms allow for a small mismatch in the frequency and spin-down values of the pulsar while coherently integrating the entire dataset. In …

Searches For Gravitational Waves From Known Pulsars At Two Harmonics In 2015–2017 Ligo Data, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration

Faculty Publications

We present a search for gravitational waves from 222 pulsars with rotation frequencies 10 Hz. We use advanced LIGO data from its first and second observing runs spanning 2015–2017, which provides the highest-sensitivity gravitational-wave data so far obtained. In this search we target emission from both the l = m = 2 mass quadrupole mode, with a frequency at twice that of the pulsar's rotation, and the l = 2, m = 1 mode, with a frequency at the pulsar rotation frequency. The search finds no evidence for gravitational-wave emission from any pulsar at either frequency. For the l = …

Spatially Resolved Stellar Populations And Kinematics With Kcwi: Probing The Assembly History Of The Massive Early-Type Galaxy Ngc 1407, Anna Ferré-Mateu, Duncan Forbes, Richard Mcdermid, Aaron Romanowsky, Jean Brodie

Faculty Publications

Using the newly commissioned Keck Cosmic Web Imager (KCWI) instrument on the Keck II telescope, we analyze the stellar kinematics and stellar populations of the well-studied massive early-type galaxy (ETG) NGC 1407. We obtained high signal-to-noise integral field spectra for a central and an outer (around one effective radius toward the southeast direction) pointing with integration times of just 600 s and 2400 s, respectively. We confirm the presence of a kinematically distinct core also revealed by VLT/MUSE data of the central regions. While NGC 1407 was previously found to have stellar populations characteristic of massive ETGs (with radially constant …

Searches For Continuous Gravitational Waves From 15 Supernova Remnants And Fomalhaut B With Advanced Ligo, B. P. Abbott, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, C. Adams, R. X. Adhikari, V. B. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, G. Allen, A. Allocca, M. A. Aloy, P. A. Altin, A. Amato, A. Ananyeva, S. B. Anderson, W. G. Anderson, S. V. Angelova, S. Antier, S. Appert, K. Arai, M. C. Araya, J. S. Areeda, Tiffany Z. Summerscales

Faculty Publications

© 2019. The American Astronomical Society. All rights reserved. We describe directed searches for continuous gravitational waves (GWs) from 16 well-localized candidate neutron stars, assuming none of the stars has a binary companion. The searches were directed toward 15 supernova remnants and Fomalhaut b, a directly imaged extrasolar planet candidate that has been suggested to be a nearby old neutron star. Each search covered a broad band of frequencies and first and second time derivatives. After coherently integrating spans of data from the first Advanced LIGO observing run of 3.5-53.7 days per search, applying data-based vetoes, and discounting known instrumental …

Still Missing Dark Matter: Kcwi High-Resolution Stellar Kinematics Of Ngc1052-Df2, Shany Danieli, Pieter Van Dokkum, Charlie Conroy, Roberto Abraham, Aaron Romanowsky

Faculty Publications

The velocity dispersion of the ultra diffuse galaxy NGC1052-DF2 was found to be σgc = 7.8 +5.2/-2.2 km s−1, much lower than expected from the stellar mass–halo mass relation and nearly identical to the expected value from the stellar mass alone. This result was based on the radial velocities of 10 luminous globular clusters that were assumed to be associated with the galaxy. A more precise measurement is possible from high-resolution spectroscopy of the diffuse stellar light. Here we present an integrated spectrum of the diffuse light of NGC1052-DF2 obtained with the Keck Cosmic Web Imager (KCWI), with an instrumental …

Extreme Chemical Abundance Ratio Suggesting An Exotic Origin For An Ultradiffuse Galaxy, Ignacio Martín-Navarro, Aaron Romanowsky, Jean Brodie, Anna Ferr´E-Mateu, Adebusola Alabi, Duncan Forbes, Margarita Sharina, Alexa Villaume, Viraj Pandya, David Martinez-Delgado

Faculty Publications

Ultradiffuse galaxies (UDGs) are a population of extended galaxies but with relatively low luminosities. The origin of these objects remains unclear, largely due to the observational challenges of the low surface brightness Universe. We present here a detailed stellar population analysis of a relatively isolated UDG, DGSAT I, based on spectroscopic data from the Keck Cosmic Web Imager integral field unit. The star formation history of DGSAT I seems to be extended, with a mean luminosity-weighted age of ∼3 Gyr, in agreement with previous photometric studies. However, we find a very high [Mg/Fe] abundance ratio, which is extreme even in …

Carrington-Class Events As A Great Filter For Electronic Civilizations In The Drake Equation, Robert D. Loper

Faculty Publications

The Drake equation is a calculation providing an upper bound on the likely number of intelligent species in our galaxy. In order to reconcile a potentially high occurrence of intelligent extraterrestrial species with the current non-observation of them, we frequently resort to some Great Filter which represents some inevitable, cataclysmic fate (such as nuclear war, pandemic, or asteroid impact) that tends to await enough worlds to negate the expectation that the galaxy ought to be teeming with intelligent life. This paper is intended to examine one potential Great Filter for electronic-based civilizations, the impact of a Carrington-class coronal mass ejection …

A Second Galaxy Missing Dark Matter In The Ngc 1052, Pieter Van Dokkum, Shany Danieli, Roberto Abraham, Charlie Conroy, Aaron Romanowsky

Faculty Publications

The ultra-diffuse galaxy NGC1052-DF2 has a very low velocity dispersion, indicating that it has little or no dark matter. Here we report the discovery of a second galaxy in this class, residing in the same group. NGC1052-DF4 closely resembles NGC1052-DF2 in terms of its size, surface brightness, and morphology; has a similar distance of Dsbf =  19.9 2.8 Mpc; and also has a population of luminous globular clusters extending out to 7 kpc from the center of the galaxy. Accurate radial velocities of the diffuse galaxy light and seven of the globular clusters were obtained with the Low Resolution …

A Second Galaxy Missing Dark Matter In The Ngc 1052 Group, Pieter Van Dokkum, Shany Danieli, Roberto Abraham, Charlie Conroy, Aaron Romanowsky

Faculty Publications

The ultra-diffuse galaxy NGC1052-DF2 has a very low velocity dispersion, indicating that it has little or no dark matter. Here we report the discovery of a second galaxy in this class, residing in the same group. NGC1052-DF4closely resembles NGC1052-DF2 in terms of its size, surface brightness, and morphology; has a similar distance of Dsbf = 19.9 +/- 2.8 Mpc; and also has a population of luminous globular clusters extending out to >7 kpc from the center of the galaxy. Accurate radial velocities of the diffuse galaxy light and seven of the globular clusters were obtained with the Low Resolution Imaging …

Erratum: “The Sluggs Survey: A Catalog Of Globular Cluster Radial Velocities” (2017, Aj, 153, 114), Duncan Forbes, Adebusola Alabi, Jean Brodie, Aaron Romanowsky, Jay Strader, Caroline Foster, Christopher Usher, Lee Spitler, Sabine Bellstedt, Nicola Pastorello, Sreeja Kartha, Zach Jennings, Alexa Villaume, Asher Wasserman, Vincenzo Pota

Faculty Publications

We would like to point out to the reader that the catalog of globular cluster (GC) radial velocities (listed in Table 5) still contains some multiple entries. In such cases GCs were observed more than once and are recorded in Table 5 with a unique GC ID, along with their coordinates and radial velocity measurement. If the reader wishes to exclude, or average, multiple measurements then GCs within one spatial pixel (i.e., 0.119 arcsec) in R.A. and decl. can be identified. This would include two dozen GCs in the galaxies NGC 720, 1407, 2768, 3608, 4365, 4459, 4474, and 4697. …