Highlights of 2015


Clifford Will

Clifford Will is the Editor-in-Chief of Classical and Quantum Gravity

The latest CQG Highlights are now available to view.  These papers represent the most interesting and important work published in CQG in 2015.  They were selected by the CQG Editorial Board and approved at CQG’s recent annual board meeting in London.

This year marks a break from the process used in past years.  CQG Highlights used to be Continue reading

Inspiral into Gargantua; where science meets science-fiction

Niels Warburton from the Massachusetts Institute of Technology shares an insight into his latest work with Sam Gralla and Scott Hughes published in Classical and Quantum Gravity.

Niels Warburton

Niels Warburton is a Marie Curie postdoctoral fellow currently working at the Kavli Institute for Astrophysics and Space Research at the Massachusetts Institute of Technology. He works on calculating gravitational waveforms from the capture of compact objects by black holes ranging from hundreds to millions of solar masses. Outside of research he often encounters other types of waves on the waters around Boston where he is a keen sailor. Niels co-authored the article recently published in CQG with Sam Gralla of the University of Arizona and Scott Hughes at the Massachusetts Institute of Technology.

The first merging black holes recently detected by LIGO were strange objects indeed. Torturing reality so that even light cannot escape from their interiors, as they whirled around each other at over half the speed of light, the disturbances they induced in space and time propagated outwards as gravitational waves. The measured characteristic chirp, an upsweep in frequency and amplitude of the waves, signaled that the two black holes had merged into a single, larger black hole. Amazingly, though this remnant was more than sixty times as massive as our sun it could be described by just two numbers – its mass and its spin. This is an unusual property for any macroscopic object as they usually require Continue reading

Crashing Neutron Stars on the Italian Dolomites

Bruno Giacomazzo, Andrea Endrizzi, Riccardo Ciolfi, Wolfgang Kastaun share details of their latest research published in the CQG focus issue: Rattle and shine: the signals from compact binary mergers.

Bruno Giacomazzo, Andrea Endrizzi, Riccardo Ciolfi, Wolfgang Kastaun

From left to right: Bruno Giacomazzo, Andrea Endrizzi, Riccardo Ciolfi, Wolfgang Kastaun.
About the authors: Bruno Giacomazzo is an assistant professor at the Department of Physics of the University of Trento and the Principal Investigator of the numerical relativity group there. The group is currently composed of two postdocs (Riccardo Ciolfi and Wolfgang Kastaun) and two PhD students (Andrea Endrizzi and Takumu Kawamura).

At the end of 2013, after seven years spent abroad (between Germany and the USA),  Bruno Giacomazzo came back to Italy for an assistant professor position at the University of Trento in Northern Italy. He used to come to this region when he was a kid to hike or ski on the mountains, but he never thought he would have come back here to study neutron star mergers.

Thanks to financial support from MIUR (Ministry of Education, University, and Research) he was able to attract Riccardo Ciolfi and Wolfgang Kastaun from abroad and to create with them the first numerical relativity group in this part of Italy. Thanks to Continue reading

Coating thermal noise research for LIGO-India

Maya Kinley-Hanlon — an undergraduate student in the Department of Physics at the American University in Washington, DC — tells us more about her group’s work on optical coatings for LIGO-India.

Maya Kinley-Hanlon is a PhD candidate in the Department of Physics at the American University in Washington, DC.

Maya Kinley-Hanlon is an undergraduate student in the Department of Physics at the American University in Washington, DC.

Our CQG paper describes measurements of optical coatings on silica glass substrates to determine if storing the LIGO optics for many years before installing them in India will cause any problems.  The coatings are known to be fairly robust in their optical properties, but as is always the case with LIGO optics, no one has any real idea about the thermal noise properties.  Since thermal noise from the coatings is expected to be a limiting noise source in the LIGO detectors, knowing if storing the optics could cause a problem is an important issue.  I worked on this Continue reading

Waves, stability and exotic black holes

Jake Dunn and Dr Claude Warnick from the Pure Mathematics group at Imperial College, London tell us all about their research using the Klein-Gordon equation to study black holes.

Jake Dunn

Jake Dunn is a PhD student at Imperial College, London.
Claude Warnick is a Lecturer in Pure Mathematics at Imperial College, London.

There is a long standing conjecture in the theory of general relativity that the final state of the gravitational collapse of a star should be a stationary black hole modelled by the Kerr solution. To this date there remains no mathematical proof of this statement, and it seems that we may have to wait a while before this result can be established. Even the simpler problem of black hole stability is a considerable mathematical challenge.

We may think of a stationary black hole as Continue reading

What does numerical relativity have to do with detecting gravitational waves?

Heather Fong — a PhD candidate in Physics at the University of Toronto, who also loves travelling and gastronomy photography — gives us an insight into her group’s work on using numerical relativity simulations for the detection of gravitational waves.


Heather Fong, a PhD candidate in Physics at the University of Toronto.

Answer: quite a lot! Numerical relativity (NR) provides the most accurate solutions to the binary black hole problem, which is exactly the type of source LIGO wants to detect — and has succeeded at! Most of the time, LIGO’s data streams are overwhelmed with noise, and so we use a technique called matched-filtering to identify gravitational-wave signals. Finding and characterizing signals requires a massive amount of accurate waveforms, and we use semi-analytic waveform models as filters which are built using the results of NR simulations.

Why don’t we use NR alone to identify signals? It certainly would be ideal if the theoretical template waveforms were generated entirely from NR; not only would we be using the most accurate waveforms available, it would also allow us to Continue reading

Fractals and black hole shadows

Jake Shipley and Dr Sam Dolan work in the Particle Astrophysics and Gravitation group at the University of Sheffield, focusing on general relativity, wave propagation and black hole physics. Here they provide us with an insight into their research. 

Jake Shipley

Jake Shipley is a Ph.D student in the School of Mathematics and Statistics at the University of Sheffield. If Jake were a black hole, you would also see a lensed version of Dr Sam Dolan, standing behind the camera.

This has been a “miracle year” for relativity.

LIGO detected gravitational waves. The LISA Pathfinder mission demonstrated near-perfect freefall in space. And the era of gravitational-wave astronomy began in some style.

A century after black holes and gravitational waves were first predicted, we have learnt something truly mind-boggling: When two black holes collide, they shake the fabric of space-time with more power than is radiated by all the stars in the known universe put together!

The “chirps” from distant black hole collisions will travel for millions of years, at the speed of light, to reach our growing network of gravitational-wave detectors on Earth … and one day, out in space.

Next year, attention will turn to the Event Horizon Telescope (EHT): a global network of radio telescopes linked together to form an Earth-sized virtual telescope, using the technique of Very Long Baseline Interferometry. The EHT will Continue reading

Ever think about writing a book?

Adam Day

Contact Adam Day, Executive Editor, Classical and Quantum Gravity with your book proposal (adam.day [at] iop.org).

One of IOP Publishing’s core aims as a society publisher is to communicate physics of the highest quality to the scientific community.

Our new book programme serves the full audience of IOP’s journals.  The focus of this award-winning books initiative is on e-publishing, meaning that authors and readers will benefit from IOP’s ever-evolving digital publishing capabilities, rapid publication times and the enhanced reader experience that users have come to expect from online journal publishing.

Some of the key features of an e-first model include:

  • Flexibility: we can make updates to the books after publication.
  • No DRM. Designed specifically for electronic delivery, IOP ebooks will have no DRM constraints.

Continue reading

CQG gives authors visibility with the audience that matter – #GR21

If you are at the GR21 conference this week, you might have seen me present the image below.
The Audience Funnel

This represents the audience funnel. When you publish a paper, your audience go through various stages. The first of these is awareness. It’s important to realise that Continue reading

Focus issue on gravitational waves, now open for submissions

Peter Shawhan and Deirdre Shoemaker invite you to publish your next paper on gravitational waves in CQG’s new open focus issue on the topic.

Peter Shawhan

Peter Shawhan, University of Maryland

Sometimes things come together in unexpected, happy ways. At the CQG editorial board meeting in London last July, we discussed ideas for new focus issues and there was a consensus that the time was right to organize one on the general theme of gravitational waves. We could claim amazing prescience, but honestly we had no idea that Continue reading