Archive for gravitational waves

Infinite LIGO Dreams

Posted in Art, The Universe and Stuff with tags , , , , , on November 28, 2016 by telescoper

There was a special event in the School of Physics & Astronomy here at Cardiff University on Friday afternoon – the unveiling of a new work of art in our coffee area. The work, a large oil painting, called Infinite LIGO Dreams by local artist Penelope Rose Cowley was inspired by the detection of gravitational waves earlier this year:

 

gravitational-wave-artwork-copyright-penelope-cowley-16x9

You can read more about this work, and the circumstances behind its creation, at the Cardiff University website and via the Physics World blog. If you like the piece you can order a poster-sized print from Penelope Cowleys’s own website here.

The unveiling of this artwork was preceded by a drinks reception, which probably accounts for the errors that crept into the blog post I wrote on Friday after the party!

 

Cardiff: Centre of Gravity

Posted in The Universe and Stuff with tags , , , on November 17, 2016 by telescoper

It’s a very busy period for me as the Cardiff University Data Innovation Research Institute (DII) gears up for some exciting new activities in both teaching and research (of which more in due course) and embarks on is strategy for promoting and fostering interdisciplinary research across Cardiff University and beyond.

Yesterday, however, I attended an informal meeting in the School of Physics & Astronomy at which we had an update about other strategic developments in the Gravitational Physics Group, some of whose members work in the DII Following on from the first-ever detection of gravitational waves earlier this year the group has ambitious plans to build on its involvement in this discovery. Here’s a nice short video produced by Cardiff University that discusses this discovery:

 

 

Cardiff University has supported research on gravitational waves for a very long time, and it is important that it reaps the benefit now that its investment is starting to pay off. To rest on laurels at this stage would be to risk losing the benefits of that sustained investment. It was very exciting to hear about the group’s plans for further sustained expansion, which will make the Cardiff one of the leading centres of gravitational wave research  in the world.

I’ve already mentioned on this blog that a couple of new positions have already been advertised, one in gravitational wave astronomy (to consolidate existing activities in theory and data analysis) and the other in a completely new area of Gravitational Wave Experimentation. Those advertisements have now closed and the process of filling the vacancies is under way.

However, yesterday we heard of even more expansion of gravitational physics research, in the form of a new academic position in Time Domain Astronomy with particular emphasis on transient sources of electromagnetic radiation that could be associated with gravitational wave production (such as gamma-ray bursts). I’ll post the advertisement on this blog when it is available. And that’s just the start: further positions will be released over the next few years which will turn Cardiff into a true Centre of Gravity.

Exciting times!

Formation of black holes in the dark [HEAP]

Posted in The Universe and Stuff with tags , on September 28, 2016 by telescoper

Given the title of my website I could hardly resist reblogging this arXiver post. I’m not an expert on Black Hole (BH) formation, so would be interested to hear opinions on how plausible is this idea that massive BHs might form via implosion rather than following a Supernova explosion.

arXiver

http://arxiv.org/abs/1609.08411

A binary black hole (BBH) with components of 30-40 solar masses as the source of gravitational waves GW150914 can be formed from a relatively isolated binary of massive stars if both BHs are formed by implosion, namely, by complete or almost complete collapse of massive stars with no energetic SNe accompanied by a sudden mass loss that would significantly reduce the mass of the compact objects, and in most cases unbind the binary system. BBHs can also be formed by dynamical interactions in globular clusters, if the BHs are formed with no energetic SNe that would kick the BHs out from the cluster before BBH formation. Besides, if BHs of ~10 solar masses as in the source GW151226 are formed by implosion, the formation of BBHs would be prolific, and their fusion would make an important contribution to a stochastic gravitational wave background. Theoretical models set mass ranges for…

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!Happy Birthday GW150914!

Posted in The Universe and Stuff with tags , , on September 14, 2016 by telescoper

A birthday message to the first gravitational wave source to be detected, from my new office mate, Bernard Schutz!

The Rumbling Universe

Just a year ago today, after travelling some 1.4 billion years, the gravitational wave chirp we christened GW150914 passed through Earth. It disturbed the two gravitational wave detectors of the LIGO observatory enough for us to notice it, to get excited about it, and to get a large fraction of the general public excited about it! But GW150914 just kept on going and is now one further year along in its journey through the Universe. And it will keep going, spreading out and getting weaker but not otherwise being much disturbed, forever. Literally forever.

And GW150914 hardly noticed us! When we observe the Universe with our telescopes, detecting light or radio waves or gamma rays from the enormous variety of luminous objects out there, we capture the energy that enters our telescopes. The photons from a distant star terminate their journeys in our telescopes, leaving a tiny hole in the…

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Theory of Gravitational Waves [CL]

Posted in The Universe and Stuff with tags on September 8, 2016 by telescoper

Since gravitational waves are quite the thing these days I thought I’d reblog this arXiver post of a nice review article that covers all the basics for the benefit of anyone interested in finding about a bit more about the subject.

arXiver

http://arxiv.org/abs/1607.04202

The existence of gravitational radiation is a natural prediction of any relativistic description of the gravitational interaction. In this chapter, we focus on gravitational waves, as predicted by Einstein’s general theory of relativity. First, we introduce those mathematical concepts that are necessary to properly formulate the physical theory, such as the notions of manifold, vector, tensor, metric, connection and curvature. Second, we motivate, formulate and then discuss Einstein’s equation, which relates the geometry of spacetime to its matter content. Gravitational waves are later introduced as solutions of the linearized Einstein equation around flat spacetime. These waves are shown to propagate at the speed of light and to possess two polarization states. Gravitational waves can interact with matter, allowing for their direct detection by means of laser interferometers. Finally, Einstein’s quadrupole formulas are derived and used to show that nonspherical compact objects moving at relativistic speeds are powerful gravitational wave…

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Jobs in Gravitational Waves at Cardiff University

Posted in The Universe and Stuff with tags , , , , on September 5, 2016 by telescoper

Gradually settling back in here to the School of Physics & Astronomy at Cardiff University, I thought I’d indulge  in a bit of promotional activity and point out that, following on from the recent detection of gravitational waves by the Advanced LIGO Consortium, of which  Cardiff University is a member, there are two opportunities open for jobs in gravitational physics.

One is in the area of Gravitational Wave Astronomy. Here is the blurb:

The current Cardiff Gravitational Physics group has expertise in gravitational-wave data analysis, numerical relativity and source modelling, and astrophysical interpretation, and consists of four full-time and two part-time academic staff, two research fellows, five postdoctoral researchers and nine PhD students. Our research is supported by the UK Science and Technology Facilities Council (STFC), the Royal Society, and the European Horizon 2020 programme. The group is a founding member of GEO600, a member of the Laser Interferometer Gravitational-Wave Observatory (LIGO) Scientific Collaboration and has played a leading role in these collaborations from their inception through to the recent first direct detection of gravitational waves, and is also active in planning and development of future detectors, such as LIGO-India, Einstein Telescope and Laser Interferometer Space Antenna (LISA).

This new appointment is part of a long-term expansion of the group, to broaden and strengthen our current research in gravitational-wave astronomy, and to build a world-leading group in gravitational-wave experimentation.

For the full advertisement, links to further particulars etc, see here.

The other is the area of Gravitational Wave Experimentation:

The current Cardiff Gravitational Physics group has expertise in gravitational-wave data analysis, numerical relativity and source modelling, and astrophysical interpretation, and consists of four full-time and two part-time academic staff, two research fellows, five postdoctoral researchers and nine PhD students. Our research is supported by the UK Science and Technology Facilities Council (STFC), the Royal Society, and the European Horizon 2020 programme. The group is a founding member of GEO600, a member of the Laser Interferometer Gravitational-Wave Observatory ( LIGO) Scientific Collaboration and has played a leading role in these collaborations from their inception through to the recent first direct detection of gravitational waves, and is also active in planning and development of future detectors, such as LIGO-India, Einstein Telescope and Laser Interferometer Space Antenna ( LISA).

This new appointment is part of a long-term expansion of the group, to broaden and strengthen our current research in gravitational-wave astronomy, and to build a world-leading group in gravitational-wave experimentation, with additional appointments expected in the near future.

For full details on this one see here.

The second appointment is intended to build on existing strengths by adding a more experimental dimension to Cardiff’s research in Gravitational Waves.

 

A Second Gravitational Wave Source!

Posted in The Universe and Stuff with tags , , on June 16, 2016 by telescoper

I was travelling back from Cambridge on the train yesterday afternoon when I saw the announcement that the Advanced LIGO team had found a second gravitational wave source. Actually, I knew this one was coming – the event actually registered last Christmas – but I had forgotten that it was to be announced at the American Astronomical Society meeting that’s happening now in San Diego. There’s also a second possible discovery, but with much lower signal-to-noise.

The full discovery paper can be found here, from which I have taken this figure:

GW

You can find the arXiv version here.
The  signal shown above, code-named GW151226, like the previous one, appears to be from a black hole binary coalescence but it involves two black holes of rather lower masses (about 14 and 8 solar masses respectively). This means that the timescale is rather longer and so more orbits can be observed. It may not look visually as clear as the first source, GW150914, which involved black holes with masses in the region of 30 solar masses, but it’s a clear detection and it’s also interesting that the models suggest that at least one of the black holes has a significant spin. Interesting!

So, that’s two sources. Now we can do statistics! I was wondering last night how long it will take before every individual discovery like this is no longer reported. The same thing happened with the first few extra-solar planets but now that we have thousands, it’s only a subset – those that might plausibly be similar to Earth – that get press attention. At the current rate of discovery gravitational-wave sources may well become quite common over the next few years. In fact a reasonable prediction for when LIGO is switched on again at the end of the summer that there might be a detection every week or so. The era of gravitational wave astronomy is definitely upon us!

Actually from my point of view the really interesting challenge is to make full use of the low signal-to-noise detections that are probable sources but with some uncertainty. I hope to write a blog post soon about how Bayesian methods can help a great deal with that.

Anyway, that’s all I’ve got time for right now. After three days in Cambridge as External Examiner, I now have to chair our undergraduate finalist examination board here at Sussex. So I’ll just say congratulations again to the LIGO team. Great stuff.