Physical Sciences and Mathematics | Open Access Articles

Starlight In The Night: Discovering The Secret Lives Of Stars, Shane L. Larson

Public Talks

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Dark Side Of The Universe: Dark Matter In The Galaxy And Cosmos, Shane L. Larson

Public Talks

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From Quarks To The Cosmos, Shane L. Larson

Colloquia and Seminars

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Whispers From The Cosmos: Seeing The Universe In Gravitational Waves, Shane L. Larson

Colloquia and Seminars

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The First Frontier: Harbor In Near Space, Shane L. Larson

Public Talks

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Connections To The Cosmos: The Search For Life Beyond Earth, Shane L. Larson

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The First Frontier: High Altitude Ballooning And Access To Near Space, Shane L. Larson

Colloquia and Seminars

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Monsters In The Cosmic Sea: Black Holes And Einstein's Astrophysical Legacy, Shane L. Larson

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Oases In The Dark: Galaxies As Probes Of The Cosmos, Shane L. Larson

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Gravitational Wave Bursts From The Galactic Massive Black Hole, Clovis Hopman, Marc Freitag, Shane L. Larson

All Physics Faculty Publications

The Galactic massive black hole (MBH), with a mass of M_•= 3.6 × 10⁶ M_⊙, is the closest known MBH, at a distance of only 8 kpc. The proximity of this MBH makes it possible to observe gravitational waves (GWs) from stars with periapse in the observational frequency window of the Laser Interferometer Space Antenna (LISA). This is possible even if the orbit of the star is very eccentric, so that the orbital frequency is many orders of magnitude below the LISA frequency window, as suggested by Rubbo, Holley-Bockelmann & Finn (2006). …

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Semi-Relativistic Approximation To Gravitational Radiation From Encounters With Non-Spinning Black Holes, Jonathan R. Gair, Daniel J. Kennefick, Shane L. Larson

All Physics Faculty Publications

The capture of compact bodies by black holes in galactic nuclei is an important prospective source for low frequency gravitational wave detectors, such as the planned Laser Interferometer Space Antenna. This paper calculates, using a semirelativistic approximation, the total energy and angular momentum lost to gravitational radiation by compact bodies on very high eccentricity orbits passing close to a supermassive, nonspinning black hole; these quantities determine the characteristics of the orbital evolution necessary to estimate the capture rate. The semirelativistic approximation improves upon treatments which use orbits at Newtonian order and quadrupolar radiation emission, and matches well onto accurate Teukolsky …

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Lisa Time-Delay Interferometry Zero-Signal Solution: Geometrical Properties, Massimo Tinto, Shane L. Larson

All Physics Faculty Publications

Time-delay interferometry (TDI) is the data processing technique needed for generating interferometric combinations of data measured by the multiple Doppler readouts available onboard the three Laser Interferometer Space Antenna (LISA) spacecraft. Within the space of all possible interferometric combinations TDI can generate, we have derived a specific combination that has zero response to the gravitational wave signal, and called it the zero-signal solution (ZSS). This is a two-parameter family of linear combinations of the generators of the TDI space, and its response to a gravitational wave becomes null when these two parameters coincide with the values of the angles of …

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Lisa Data Analysis: Source Identification And Subtraction, Neil J. Cornish, Shane L. Larson

All Physics Faculty Publications

The Laser Interferometer Space Antenna will operate as an AM-FM receiver for gravitational waves. For binary systems, the source location, orientation and orbital phase are encoded in the amplitude and frequency modulation. The same modulations spread a monochromatic signal over a range of frequencies, making it difficult to identify individual sources. We present a method for detecting and subtracting individual binary signals from a data stream with many overlapping signals.

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Lisa, Binary Stars, And The Mass Of The Graviton, Curt Cutler, William A. Hiscock, Shane L. Larson

All Physics Faculty Publications

We extend and improve earlier estimates of the ability of the proposed LISA (Laser Interferometer Space Antenna) gravitational wave detector to place upper bounds on the graviton mass m_g by comparing the arrival times of gravitational and electromagnetic signals from binary star systems. We show that the best possible limit on m_g obtainable this way is ∼50 times better than the current limit set by solar system measurements. Among currently known, well-understood binaries, 4U1820-30 is the best for this purpose; LISA observations of 4U1820-30 should yield a limit ≈3-4 times better than the present solar system bound. AM …

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The Lisa Optimal Sensitivity, Thomas A. Prince, Massimo Tinto, Shane L. Larson, J. W. Armstrong

All Physics Faculty Publications

The multiple Doppler readouts available on the Laser Interferometer Space Antenna (LISA) permit simultaneous formation of several interferometric observables. All these observables are independent of laser frequency fluctuations and have different couplings to gravitational waves and to the various LISA instrumental noises. Within the functional space of interferometric combinations LISA will be able to synthesize, we have identified a triplet of interferometric combinations that show optimally combined sensitivity. As an application of the method, we computed the sensitivity improvement for sinusoidal sources in the nominal, equal-arm LISA configuration. In the part of the Fourier band where the period of the …

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Unequal Arm Space-Borne Gravitational Wave Detectors, Shane L. Larson, Ronald W. Hellings, William A. Hiscock

All Physics Faculty Publications

Unlike ground-based interferometric gravitational wave detectors, large space-based systems will not be rigid structures. When the end stations of the laser interferometer are freely flying spacecraft, the armlengths will change due to variations in the spacecraft positions along their orbital trajectories, so the precise equality of the arms that is required in a laboratory interferometer to cancel laser phase noise is not possible. However, using a method discovered by Tinto and Armstrong, a signal can be constructed in which laser phase noise exactly cancels out, even in an unequal arm interferometer. We examine the case where the ratio of the …

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Testing Of The New Usgs K Index Algorithm At Bear Lake, Ariel O. Acebal

All U.S. Government Documents (Utah Regional Depository)

The K index was developed by Bartels in 1939 as an estimate of the level of geomagnetic activity caused by the Sun. This index was computed manually every three hours at geomagnetic observatories using the magnetic traces of the surface planetary magnetic field. In 1991, the International Association of Geomagnetism and Aeronomy approved four additional methods to compute the K index; all of them were computer algorithms. One of the approved methods, the Wilson code, recently underwent some modifications. The new algorithm is now part of a Windows-based computer program being developed by the United States Geological Survey (USGS). After …

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Sensitivity Curves For Spaceborne Gravitational Wave Interferometers, Shane L. Larson, William A. Hiscock, Ronald W. Hellings

All Physics Faculty Publications

To determine whether particular sources of gravitational radiation will be detectable by a specific gravitational wave detector, it is necessary to know the sensitivity limits of the instrument. These instrumental sensitivities are often depicted (after averaging over source position and polarization) by graphing the minimal values of the gravitational wave amplitude detectable by the instrument versus the frequency of the gravitational wave. This paper describes in detail how to compute such a sensitivity curve given a set of specifications for a spaceborne laser interferometer gravitational wave observatory. Minor errors in the prior literature are corrected, and the first (mostly) analytic …

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Using Binary Star Observations To Bound The Mass Of The Graviton, Shane L. Larson, William A. Hiscock

All Physics Faculty Publications

Interacting white dwarf binary star systems, including helium cataclysmic variable (HeCV) systems, are expected to be strong sources of gravitational radiation, and should be detectable by proposed space-based laser interferometer gravitational wave observatories such as LISA. Several HeCV star systems are presently known and can be studied optically, which will allow electromagnetic and gravitational wave observations to be correlated. Comparisons of the phases of a gravitational wave signal and the orbital light curve from an interacting binary white dwarf star system can be used to bound the mass of the graviton. Observations of typical HeCV systems by LISA could potentially …

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Temporal Change Enhancement In Multispectral Images Remotely Sensed From Satellites, William P. Pfaff

Utah Space Grant Consortium

The application of principal components analysis to multispectral satellite images is a routine way to present the data in false-color composite images. These composite images include a very high percentage of available information and have no correlation between the displayed colors. The transformation of multispectral image data into its principal components is also an effective way to separate image information from noise. This paper describes a procedure for temporal change enhancement which exploits both the decorrelation and noise isolation properties of the principal components transformation. Using simulated temporal change, this procedure was demonstrated to be more effective than the standard …

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Astrophysical Bounds On Global Strings, Shane L. Larson, William A. Hiscock

All Physics Faculty Publications

Global topological defects produce nonzero stress energy throughout spacetime, and as a result can have observable gravitational influence on surrounding matter. Gravitational effects of global strings are used to place bounds on their cosmic abundance. The minimum separation between global strings is estimated by considering the defects' contribution to the cosmological energy density. More rigorous constraints on the abundance of global strings are constructed by examining the tidal forces such defects will have on observable astrophysical systems. The small number of observed tidally disrupted systems indicates there can be very few of these objects in the observable Universe.

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Semiclassical Effects In Black Hole Interiors, William A. Hiscock, Shane L. Larson, Paul R. Anderson

All Physics Faculty Publications

First-order semiclassical perturbations to the Schwarzschild black hole geometry are studied within the black hole interior. The source of the perturbations is taken to be the vacuum stress-energy of quantized scalar, spinor, and vector fields, evaluated using analytic approximations developed by Page and others (for massless fields) and the DeWitt-Schwinger approximation (for massive fields). Viewing the interior as an anisotropic collapsing cosmology, we find that minimally or conformally coupled scalar fields, and spinor fields, decrease the anisotropy as the singularity is approached, while vector fields increase the anisotropy. In addition, we find that for massless fields of all spins, the …

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Full-Text Articles in Physical Sciences and Mathematics

Starlight In The Night: Discovering The Secret Lives Of Stars, Shane L. Larson

Public Talks

Dark Side Of The Universe: Dark Matter In The Galaxy And Cosmos, Shane L. Larson

Public Talks

From Quarks To The Cosmos, Shane L. Larson

Colloquia and Seminars

Whispers From The Cosmos: Seeing The Universe In Gravitational Waves, Shane L. Larson

Colloquia and Seminars

The First Frontier: Harbor In Near Space, Shane L. Larson

Public Talks

Connections To The Cosmos: The Search For Life Beyond Earth, Shane L. Larson

Public Talks

The First Frontier: High Altitude Ballooning And Access To Near Space, Shane L. Larson

Colloquia and Seminars

Monsters In The Cosmic Sea: Black Holes And Einstein's Astrophysical Legacy, Shane L. Larson

Public Talks

Oases In The Dark: Galaxies As Probes Of The Cosmos, Shane L. Larson

Public Talks

Gravitational Wave Bursts From The Galactic Massive Black Hole, Clovis Hopman, Marc Freitag, Shane L. Larson

All Physics Faculty Publications

Semi-Relativistic Approximation To Gravitational Radiation From Encounters With Non-Spinning Black Holes, Jonathan R. Gair, Daniel J. Kennefick, Shane L. Larson

All Physics Faculty Publications

Lisa Time-Delay Interferometry Zero-Signal Solution: Geometrical Properties, Massimo Tinto, Shane L. Larson

All Physics Faculty Publications

Lisa Data Analysis: Source Identification And Subtraction, Neil J. Cornish, Shane L. Larson

All Physics Faculty Publications

Lisa, Binary Stars, And The Mass Of The Graviton, Curt Cutler, William A. Hiscock, Shane L. Larson

All Physics Faculty Publications

The Lisa Optimal Sensitivity, Thomas A. Prince, Massimo Tinto, Shane L. Larson, J. W. Armstrong

All Physics Faculty Publications

Unequal Arm Space-Borne Gravitational Wave Detectors, Shane L. Larson, Ronald W. Hellings, William A. Hiscock

All Physics Faculty Publications

Testing Of The New Usgs K Index Algorithm At Bear Lake, Ariel O. Acebal

All U.S. Government Documents (Utah Regional Depository)

Sensitivity Curves For Spaceborne Gravitational Wave Interferometers, Shane L. Larson, William A. Hiscock, Ronald W. Hellings

All Physics Faculty Publications

Using Binary Star Observations To Bound The Mass Of The Graviton, Shane L. Larson, William A. Hiscock

All Physics Faculty Publications

Temporal Change Enhancement In Multispectral Images Remotely Sensed From Satellites, William P. Pfaff

Utah Space Grant Consortium

Astrophysical Bounds On Global Strings, Shane L. Larson, William A. Hiscock

All Physics Faculty Publications

Semiclassical Effects In Black Hole Interiors, William A. Hiscock, Shane L. Larson, Paul R. Anderson

All Physics Faculty Publications