Leonard E Parker

Center for Gravitation, Cosmology & Astrophysics

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Leonard E Parker Center for Gravitation, Cosmology and Astrophysics

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The Leonard E Parker Center for Gravitation, Cosmology and Astrophysics is supported by NASA, the National Science Foundation, UW-Milwaukee College of Letters and Science, and UW-Milwaukee Graduate School. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of these organizations.


GW150914: First results from the search for binary black hole coalescence with Advanced LIGO

The results on the most significant Gravitational Wave event, GW150914, during LIGO’s first observation run using relativistic models of compact binary waveforms Read more small arrow icon

Properties of the binary black hole merger GW150914

We characterize the properties of the source of the first gravitational wave directly detected in history and estimate the values of its parameters. Read more small arrow icon

The First Two Years of Electromagnetic Follow-Up with Advanced LIGO and Virgo

Observing both gravitational and electromagnetic channels simultaneously! Read more small arrow icon

Search for gravitational wave ringdowns from perturbed intermediate mass black holes in LIGO-Virgo data from 2005-2010

Searching for an elusive class of objects that have masses up to 100,000 times the mass of our Sun - intermediate mass black holes. Read more small arrow icon

Systematic and statistical errors in a bayesian approach to the estimation of the neutron-star equation of state using advanced gravitational wave detectors

Measurements of gravitational wave parameters, using the Advanced gravitational-waves detectors, can be used to constrain the neutron-star equation of state. Read more small arrow icon

Advanced LIGO's ability to detect apparent violations of the cosmic censorship conjecture and the no-hair theorem through compact binary coalescence detections

The Advanced LIGO gravitational wave detectors will be capable of detecting violations of cherished beliefs about the nature of gravity. Read more small arrow icon

Extracting equation of state parameters from black hole-neutron star mergers

Next-generation telescopes will capture gravitational waveforms with sufficient accuracy to describe the departure from point-particle dynamics during the inward spiral of two objects. Constraints will be placed on the neutron star equation of state. Read more small arrow icon

Discovery of the Optical/Ultraviolet/Gamma-Ray Counterpart to the Eclipsing Millisecond Pulsar J1816+4510

The discovery of a gamma-ray counterpart to the 3.2-ms pulsar J1816+4510 is reported, along with strong evidence of an optical / ultraviolet companion. Read more small arrow icon

First Low-Latency LIGO+Virgo Search for Binary Inspirals and their Electromagnetic Counterparts

Much can be learned from the coincident observation of electromagnetic radiation and gravitational waves. For the first time, LIGO and Virgo performed a low-latency search for gravitational waves and provided alerts to ten partner telescopes. Read more small arrow icon

Eccentric Black Hole-Neutron Star Mergers

New simulations of black hole - neutron star mergers with high eccentricity show a wide range of outcomes, depending on the impact parameter. The observed variations may help explain the diverse characteristics in gamma-ray bursts. Read more small arrow icon

A Closer Look at a Young, Distant Galaxy

Many galaxies have recently been discovered at very high redshift (z>5). The properties of galaxy Q2343-BX418 at z=2.3 may shed light on the likely physical conditions in these higher redshift objects before they can be measured directly. Read more small arrow icon

Calculating the Gravitational Self-Force

The gravitational self-force experienced by a particle is essential to developing accurate gravitational waveforms. The calculation of the self-force was performed in the radiation gauge, assuming a circular orbit in a Schwarzschild spacetime. Read more small arrow icon

Home Computers Discover New Pulsar through Einstein@Home

Einstein@Home harnesses the computing power of hundreds of thousands of home computers. For the first time, home computers enrolled in Einstein@Home discovered a new pulsar. Read more small arrow icon

Astronomers make first-time measurement using binary system

Ground-based observations of a newly-discovered binary white dwarf system (NLTT 11748) were used to measure the relativistic beaming effect. This is the first such observation for a binary white dwarf system. Read more small arrow icon

New Simulations Explore Preheating in the Early Universe

After the universe expanded during inflation, models suggest a 'preheating' process occurred. Simulations of the inflaton interacting with multiple matter fields during preheating are used to predict the resulting gravitational-wave spectrum today. Read more small arrow icon

Auger reaches for highest energy particles to look beyond the standard model

The Pierre Auger Observatory provides a laboratory for studying fundamental physics at energies far beyond those available at particle colliders. Cosmic neutrino observations will probe for new physics phenomena beyond the standard model. Read more small arrow icon

Cosmic Collisions: Searching for Gravitational-wave Signatures

The violent collisions and mergers of neutron stars and black holes create distinct gravitational-wave signatures. For the first time, the LIGO and Virgo collaborations joined forces to search for gravitational waves from these cosmic events. Read more small arrow icon

Guiding Light: A Gravitational-Wave Search Based on Gamma-Ray Burst Observations

Fantastic explosions known as gamma-ray bursts have been captured by several satellites. Some of these events may produce gravitational waves. LIGO and Virgo search for them just seconds before the satellite observations occurred. Read more small arrow icon

Seeking Messengers from the Early Universe

Gravitational waves emitted shortly after the Big Bang carry unaltered information about the physical processes that generated them. A major milestone was achieved when LIGO's search resulted in new constraints on early universe models. Read more small arrow icon

Correlation of the Highest-Energy Cosmic Rays with Nearby Extragalactic Objects

Origin of the highest-energy cosmic rays discovered? Read more small arrow icon

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