Archive for LISA

PhD Studentship in Gravitational Wave Astrophysics at Maynooth University!

Posted in Uncategorized with tags , , , , on February 11, 2020 by telescoper

With the arrival of Dr John Regan in the Department of Theoretical Physics at Maynooth University we are delighted to announce a fully-funded PhD studentship. In order to boost the circulation, here’s a copy of the advert you can find on John’s own website.



Project Description. Recent detections of gravitational waves from stellar mass sized black holes with the LIGO observatory has opened up a new window for black hole astrophysics as well as heralding the dawn of multimessenger astrophysics. LIGO is sensitive to the mergers of black holes in the range 10 solar masses up to approximately 100 solar masses out to a few Megaparsecs.

LISA is the planned, next generation, space-based gravitational wave observatory due for launch in 2034. LISA will be sensitive to gravitational waves at a much lower frequency compared to LIGO and as a result will be able to detect the mergers of both much larger and much more distant black holes. Planning for LISA is now well underway and the science base and objectives are being determined.

This PhD project will involve computing gravitational wave forms from mergers of massive black holes from the early Universe – which will be detectable by LISA. The origin of massive black holes is currently unknown and hence being able to detect their mergers from the early Universe is seen as a critical aspect in understanding their formation pathways. In this project the student will use the state-of-the-art Enzo-E code to model the mergers of black holes. In doing so the student will be able to accurately compute the gravitational wave signal from black holes which are merging in the distant Universe thus making predictions for LISA.

Student fees and a full stipend (€18k per annum) are available as part of this studentship.

Candidate Criteria. Applicants should have (or be about to complete) an undergraduate degree and/or taught postgraduate degree in (applied) mathematics, (theoretical) physics, computer science or a related discipline. Past experience shows that successful applicants usually have a very good first class degree (or equivalent). Applicants with computational experience are particularly encouraged to apply. In addition, the applicants must have excellent communication, planning and team working skills.

Application Procedure

Application Deadline: Friday May 1st 2020

Students who wish to apply for this studentship should apply in writing to Please put “PhD Studentship Position” in the subject of the email. The application must comprise:

  • A full CV
  • A covering letter outlining why you wish to pursue this PhD program
  • Two references, preferably from your current academic institution, outlining your suitability for the position

Shortlisted candidates will be notified of the outcome of the selection process in early May with interviews in mid-late May. The start date for the PhD is expected to be September 2020.

Please direct any questions or queries on the above position to Dr. John Regan (



LISA gets the go-ahead!

Posted in The Universe and Stuff with tags , , , , , on June 21, 2017 by telescoper

Just taking a short break from examining duties to pass on the news that the European Space Agency has selected the Laser Interferometric Space Experiment (LISA) – a gravitational wave experiment in space – for its large mission L3. This follows the detection of gravitational waves using the ground-based experiment Advanced LIGO and the success of a space-based technology demonstrator mission called Lisa Pathfinder.

LISA consists of a flotilla of three spacecraft in orbit around the Sun forming the arms of an interferometer with baselines of the order of 2.5 million kilometres, much longer than the ~1km arms of Advanced LIGO. These larger dimensions make LISA much more sensitive to long-period signals. Each of the LISA spacecraft contains two telescopes, two lasers and two test masses, arranged in two optical assemblies pointed at the other two spacecraft. This forms Michelson-like interferometers, each centred on one of the spacecraft, with the platinum-gold test masses defining the ends of the arms.

Here’s an artist’s impression of LISA:

This is excellent news for the gravitational waves community, especially since LISA was threatened with the chop when NASA pulled out a few years ago. Space experiments are huge projects – and LISA is more complicated than most – so it will take some time before it actually happens. At the moment, LISA is pencilled in for launch in 2034…

Lisa Pathfinder: it works!

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

Just time for a quick post to pass on some impressive news from LISA Pathfinder (which is basically a technology demonstrator mission intended to establish the feasibility of a proposed space-based gravitational wave facility called LISA). LISA Pathfinder is ostensibly an extremely simple experiment, consisting of two metal cubes (made of a gold-platinum mixture) about 38cm apart. The question it tries to answer is how accurately these two cubes can be put an ideal “free-fall” state, i.e. when the only force acting on them is gravity.

Here’s a short explanatory video about the latest results:

The technical details are presented in a paper in Physical Review Letters, from which the key figure is this:


Lisa_PathfinderThis shows very clearly that the performance of the LISA Pathfinder experiment (as shown by the red measurements) comfortably exceeds the requirements of the full LISA experiment (black curve). Indeed, these results, from only two months of science operations, show that the two cubes are in free-fall to a precision more than five times better than originally required.

So, not to put too fine a point on it,  it works!



Lisa Pathfinder – better late than never!

Posted in Science Politics, The Universe and Stuff with tags , , , , , , , on December 3, 2015 by telescoper

Determined to post about something positive after yesterday’s act of collective idiocy by Parliament I find myself given a golden opportunity by today’s successful launch of the Lisa Pathfinder experiment by the European Space Agency.

As space missions go, LISA Pathfinder seems quite a modest one: it is basically a pair of identical 46 mm gold–platinum cubes separated by 38 cm. The idea is to put these test masses in free fall and measure their relative positions as accurately as possible.

After a false start yesterday, LISA Pathfinder was successfully launched in the early hours of this morning and is now en route to the First Lagrangian Point of the Earth-Sun system, about 1.5 million miles from Earth, at the location marked L1 in the diagram:


The contours show the “effective potential” of the Earth-Sun system, which takes into account the effect of rotation as well as gravity. The five Lagrangian points are the places at which tis effective potential is locally flat, i.e. where its spatial gradient vanishes. Any physics student will know that when the gradient of the potential is zero there is no force on a test particle. What this means is that an object placed exactly at any of the 5 Lagrangian points stays in the same position relative to the Earth and Sun as the system rotates. Put a spacecraft at one of these points, therefore, and it stays put when viewed in a frame rotating around the Sun  at the same speed as the Earth.

It’s not quite as simple as this because, as you will observe the Lagrangian points are not stable: L1, L2 and L3 are saddle-points; a  stable point would be a local minimum. However, around the first three there are stable orbits so in effect a test mass displaced from L1, say, oscillates around it without doing anything too drastic. L4 and L5 can be stable or unstable, in a general system but are stable for the case of the Solar System, hence the tendency of asteroids (the Trojans) to accumulate at these locations.

You may remember that WMAP, Planck and Herschel were all parked in orbits around L2. A spacecraft positioned exactly at L2 is permanently screened from the Sun by the Earth. That might be very useful if you want to do long-wavelength observations that require very cool detectors, but not if you want to use the Sun as a source of power. In any case, as I explained above, spacecraft are not generally located exactly at L2 but in orbit around it. Planck in fact had solar cells on the base of the satellite that provided power but also formed a shield as they always faced the Sun as the satellite rotated and moved in its orbit to map the sky. The choice of L1 for LISA Pathfinder was made on the basis of spacecraft design considerations as it will operate in a very different manner from Planck.

The reason for doing eLISA is to demonstrate the technological feasibility of a much more ambitious planned gravitational wave detector in space originally called LISA, but now called eLISA. The displacement of test masses caused by gravitational waves is tiny so in order for eLisa it is necessary (a) to screen out every effect other than gravity, e.g. electromagnetic interactions due to residual charges, to great precision and (b) to measure relative positions to great accuracy. That’s why it was decided to fly a cheaper technology demonstrator mission, to prove the idea is feasible.

LISA Pathfinder won’t make any science discoveries but hopefully it will pave the way towards eLISA.

It has to be said that LISA Pathfinder has had a fairly troubled history. I just had a quick look at some papers I have dating back to the time when I was Chair of PPARC Astronomy Advisory. Among them I found the categorical statement that

LISA Pathfinder will be launched in 2009.

Hmm. Not quite. It’s obviously running quite a long way behind schedule and no doubt considerably over its initial budget but it’s good to see it under way at last. There will be a lot of sighs of relief that LISA Pathfinder has finally made it into space! Now let’s see if it can do what it is supposed to do!




Bad News for Astrophysics from ESA

Posted in Science Politics, The Universe and Stuff with tags , , , , , , , , on April 18, 2012 by telescoper

Just a quick post to pass on the news (which I got from Steinn Sigurdsson’s blog) that the ESA Executive (see correction in comments below) Space Science Advisory Committee (SSAC) of the European Space Agency (ESA) has made a recommendation as to the next large mission to be flown. The short list consisted of a mission to Jupiter’s moons (JUICE), an X-ray observatory (ATHENA), and a gravitational wave observatory (NGO). The last two of these are severely de-scoped versions of missions (IXO and LISA respectively) that had to be re-designed in the aftermath of decisions made in the US decadal review not to get involved in them.

Not unexpectedly, the winner is JUICE. Barring a rejection of this recommendation by the ESA Science Programme Committee (SPC) this will be the next big thing for ESA space science.

The School of Physics and Astronomy at Cardiff University has a considerable involvement in gravitational wave physics, so the decision is disappointing for us but not entirely surprising. It’s not such a big blow either, as we are mainly involved in ground-based searches such as LIGO.

The biggest local worry will be for the sizeable community of X-ray astronomers in the UK. With no big new facilities likely for well over a decade one wonders how the expertise in this area can be sustained into the future, even if LOFT is selected as one of the next medium-sized missions. Or, given that STFC funding is already spread extremely thin, perhaps this is time for the UK to organize a strategic withdrawal from X-ray astronomy?

Gravity waves goodbye to LISA?

Posted in Science Politics, The Universe and Stuff with tags , , , on April 8, 2011 by telescoper

It seems that we’re not allowed to have any good news these days without a bit of bad to go with it. This week it has emerged here and there that the US National Aeronautics and Space Administration (better known as NASA) is pulling the plug on one of the most exciting space missions on its drawing board. Feeling the pressure of budget constraints and a ballooning overspend on the James Webb Space Telescope (JWST), NASA has decided not to participate further in the Laser Interferometric Space Antenna, a.k.a. LISA. The project teams working on LISA have been disbanded, and the shutters have been pulled down on a project which would have revolutionised astrophysics by opening up new possibilities of observing astronomical objects using gravitational waves, rather than electromagnetic radiation.

This does not mean that LISA is necessarily completely dead. For one thing, it was always planned to be a partnership between NASA and its European counterpart ESA (the European Space Agency); you can find ESA’s LISA page here. In fact a technological demonstrating mission LISA-Pathfinder, operated by ESA, is scheduled for launch in 2013.
It remains possible that ESA will proceed on its own with some version of LISA, although given its own financial constraints it is unlikely that it will be able to fund the full original mission concept. The best we can hope for, therefore, is probably some slimmed-down low-budget version and perhaps an even later launch date.

I still hold out some hope that LISA might come out of mothballs when gravitational waves are actually detected. This may well be accomplished by Advanced LIGO, a ground-based interferometric system based in the states, although it has to be said that gravitational waves have been “on the brink of detection” for at least 30 years and still haven’t actually been found. When detection does become a reality it might galvanise NASA into finding room in its budget again.

This news will be a particularly concern for the sizeable Gravitational Physics group here in the School of Physics & Astronomy at Cardiff University. However, LISA was very much in the planning and development stages so it won’t impact their current work. I haven’t had the chance to discuss the news about LISA with members of this group, so I’d be interested to receive comments from them, or indeed anyone else who knows more about what NASA’s decision may or not mean for the future of gravitational wave physics.