Ulrich Sperhake named APS Fellow

Tuesday, October 11, 2016

Ulrich Sperhake, Adjunct Professor at the University of Mississippi and long-term collaborator of our group, is one of the newly elected Fellows of the American Physical Society. A list of all Fellows elected by the Division of Gravitational Physics in 2016 is available here. Congratulations, Uli!

Black Hole Spectroscopy in Physical Review Letters

Friday, September 2, 2016

Our paper Spectroscopy of Kerr black holes with Earth- and space-based interferometers was published today in Physical Review Letters.

Advanced LIGO detected gravitational waves from merging black holes with surprisingly high signal-to-noise ratio. The oscillation frequencies of the merger remnant can be used - just like atomic lines - to do black hole spectroscopy: they will tell us whether the merger remnant is indeed a rotating black hole, as predicted by Einstein’s general relativity. However, black hole spectroscopy requires signal-to-noise ratios higher than the first LIGO detection.

In this paper we use state-of-the-art astrophysical models of black hole formation and a comprehensive catalog of projected noise sensitivities to answer the following question: how many events will allow us to do black hole spectroscopy in the future, as we improve our detectors? Is it sufficient to upgrade Earth-based interferometers or do we need a space-based detector such as eLISA, whose technological feasibility was recently demonstrated by the spectacular success of LISA Pathfinder?

We find that significant improvements in Earth-based detectors (or better data analysis techniques) will be necessary to routinely perform black hole spectroscopy on Earth, while most massive black hole merger detections in space will allow us to test the black hole nature of the remnant.

Research highlights in CQG and PRD

Friday, August 12, 2016

Some papers from our group were recently selected as research highlights in Classical and Quantum Gravity (CQG) and Physical Review D (PRD).

CQG selected two papers by the LIGO collaboration (a review of Advanced LIGO and a paper on detector characterization) as well as our review on tests of general relativity for their annual 2015 Highlights collection.

Today, our paper on astrophysical applications of the post-Tolman-Oppenheimer-Volkoff approximation was published in PRD as an Editor’s Suggestion.

ICTS Summer School Lectures

Wednesday, August 3, 2016

Over the last three years the International Center for Theoretical Sciences (Tata Institute of Fundamental Research, Bangalore, India) has been organizing summer/winter schools on various topics in gravitational-wave (GW) physics and astronomy. Each school from this series targeted a particular sub-area (theory, experiment, data science, etc) of GW science. This year’s school has special significance because of the first direct detection of GWs by the LIGO observatories. The school involves three graduate-level courses in theoretical GW physics: Gravity: Newtonian, post-Newtonian, Relativistic by Clifford M. Will; Gravitational Astronomy by Bangalore S. Sathyaprakash; and Black Hole Perturbation Theory by Emanuele Berti. Videos of the lectures and lecture materials can be found here.

L3ST Study Interim Report

Monday, August 1, 2016

The L3 Study Team Interim Report has been released and posted on the PCOS website. The L3 Study Team was charged to provide an analysis of potential US hardware contributions to the ESA-led L3 Gravitational Wave mission and an assessment of their consequences on cost, risk, and science return. Some highlights from the report:

• The science case for a space-based GW observatory, endorsed by both the 2010 Decadal Survey and ESA’s 2013 Cosmic Visions process, remains compelling. Realizing a mission that fully delivers this science in a timely fashion and with low risk should be the primary objective of US participation in L3.

• The L3ST concurs with the ESA’s GOAT report that meaningful participation of the US community in the design, development, and operation of L3 will result in a mission that is more technically robust and more scientifically capable.

• US contribution of central elements of the payload is an effective way to enable meaningful participation and provide impact on, and insight into, the final flight design.

• The US has strengths in a broad range of technologies relevant to L3. Opportunities should be sought to employ all of these strengths in the partnership regardless of the specific hardware items delivered.

A conclusion of our analysis is that multiple viable options of US participation in L3 exist, each with a different mix of cost, risk, and impact. While it is likely that the US will only contribute a subset of these items to the final partnership, continuing some level of development across the entire portfolio is an effective strategy to reduce overall mission risk as well as provide additional insight to the US science and technology communities.