Archive for Aoibhinn Gallagher

After Conferring

Posted in Biographical, Maynooth with tags , , on October 30, 2025 by telescoper
from left to right: Dr Neil Trappe (HoD, Physics); Dr John Regan; Dr Aoibhinn Gallagher; Dr Matthew Birney; Dr Hannah O’Brennan; me; Dr Jonivar Skullerud

Yesterday I attended a conferring ceremony at Maynooth which was a very special occasion because it involved the formal award of the PhD degree to Aoibhinn Gallagher whom I supervised. Two other research students from the Department of Physics got their PhDs yesterday too; Matthew Birney and Hannah O’Brennan. Matthew (ESO Garching) and Aoibhinn (Bielefeld) both now have postdoctoral positions in Germany, incidentally.

These events are not actually called Graduation Ceremonies here in Ireland but Conferring Ceremonies. I was impressed that the local suppliers of academic dress, Phelan Conan were able to supply the correct 1989 vintage DPhil gown from Sussex University as opposed to the less interesting modern one. I would have worn it for the picture above, but by the time we found Hannah to take the photo I had already returned it to the supplier. Here are two more with myself in the gown and mortarboard:

left to right: Dr Emma Whelan; Dr Matthew Birney; Dr Aoibhinn Gallagher; me
Myself and Aoibhinn

You can see a picture of me wearing the same sort of gown in Brighton back in 1989, when I was a skinny young queen, here. I’ll add more pictures from yesterday if and when I get them.

As well as the PhDs we also saw the entire class of our MSc in Theoretical Physics and Mathematics get their degrees. I haven’t got any photographs of them, but will add any that I find. Here is a photograph of them outside the TSI building, courtesy of Jonivar Skullerud.

After the ceremony, those who got their degrees went for dinner with their respective parents, siblings and others who had come to attend the ceremony. We did meet up later on, however, in a local pub for a drink or several. In among all that I didn’t have time to write a post, bringing to an end a blogging streak of 109 days.

Graduation ceremonies are funny things. With all their costumes and weird traditions, they even seem a bit absurd. On the other hand, even in these modern times, we live with all kinds of rituals and I don’t see why we shouldn’t celebrate academic achievement in this way.

I like graduation ceremonies, actually. As each person walks across to be presented with their scroll you realize that every one of them has a unique story to tell and a whole universe of possibilities in front of them. How their lives will unfold no-one can tell, but it’s a privilege to be there for one important milestone on their journey, even those from other departments with whom you have had no contact at all.

I always find these ceremonies bittersweet occasions, though. There’s joy and celebration, of course, but these are tempered by the realization that many of the young people whom you’ve seen around long enough to grow accustomed to their faces, will disappear into the big wide world, in some cases never to be seen again. Although everyone is rightly proud of the achievement – either their own in the case of the graduands or that of others in the case of the guests – there’s also a bit of sadness to go with the goodbyes. It always seems that as a lecturer you are only just getting to know students by the time they graduate, but that’s enough to miss them when they go.

Anyway, all this is a roundabout way of saying congratulations once more to everyone who graduated yesterday, including Matthew, Hannah and Aoibhinn, and I wish you all the very best for the future!

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Moving On

Posted in Education, Maynooth with tags , , , , , , , on August 22, 2025 by telescoper

Last week I wrote a post about the loose ends of the academic year, one of which concerned my PhD student Aoibhinn, who passed her viva voce examination way back in May, who had to submit a bound copy of the thesis to the relevant office by September 6th so that her degree could be ratified by Faculty and Academic Council. She has now done that, and in the process kindly made me an extra copy of the Authorized Version to put on my shelf:

It will be easy to find on my shelf because it’s a different colour from the others. Aoibhinn will be off to Germany for a postdoctoral fellowship after her conferring ceremony in October.

In subsequent post I mentioned a plethora of meetings to take place this week, all of which went off without much incident. The various Departmental Examination Boards did their business and students will receive their results on September 5th. Students involved in these will be moving on in various ways: some will be graduating, some progressing to the next year of their course and others – though not very many at all – will be leaving without qualifying.

Meanwhile, elsewhere in Ireland, students in the Class of 25 have today been receiving their school Leaving Certificate results. As expected, the proportion at the highest grade (H1) is down significantly compared 2024. On the other hand, the total number of students taking  Leaving Certificate examinations is significantly higher  than last year. You can find all the national statistics here.

How these nationwide effects  will work their way through to undergraduate admissions at Maynooth remains to be seen. Applicants will get offers through the CAO system next week; the points required by each higher education institution should be available online on Wednesday 27th. The Irish Times traditionally publishes a pull-out supplement showing all the offers for all courses at all universities across the sector the following day, i.e. on Thursday 28th September.

By the end of next week, therefore, we’ll have some sort of an idea how many students we will have entering the University in September 2025 and can begin moving on to the next academic year. One thing I’ve already got sorted out – way ahead of previous years – is my teaching timetable for Semester 1. Usually I’ve been happy if I had this before the first week of term! My new timetable makes Tuesdays and Thursdays my heaviest teaching days, but gives me Wednesday free for research and other things that I’ve started planning already.

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Loose Ends of the Academic Year…

Posted in Biographical, Education, Maynooth with tags , , , , , , , , , on August 13, 2025 by telescoper

I know most people outside academia thing university staff are on a long holiday between June and September, but that’s not the case. This week we have been trying to sort out some of the loose ends of Academic Year 2024/5 before we start on planning for 2025/6. The matters to be dealt with include undergraduate, taught postgraduate, and research posgraduate.

To start with I’ve had to mark my undergraduate repeat (resit) examinations. The grades need to be checked and uploaded before the appropriate examination board meeting next week. That will resolve a number of progression issues, as well as hopefully allowing some students to retrieve credit from their final year and thus be allowed to graduate.

Another set of tasks related to our taught MSc students. They submitted their dissertations on Monday which now need to be read and graded before another examination board (next Monday). They also have to do their presentations, which take place this Friday (15th August).

The following week, the School leaving certificate results come out, at which point we’ll start to get some idea of how many students we will have entering the first year in September.

Today I heard that my PhD student Aoibhinn, who passed her viva voce examination way back in May, has had her thesis corrections formally approved. She now has to submit a bound copy of the thesis along with an electronic version thereof by September 6th at the latest. Then her degree has to be approved by the Faculty of Science & Engineering (on September 16th) followed by Academic Council on (29th September). Assuming those formalities are observed, she can receive her doctorate at one of the conferring ceremonies at the end of October.

Another thing I heard today is that Aoibhinn has been awarded a prestigious research fellowship from the Alexander von Humboldt Foundation but she needs her degree certificate before she can start. That’s a stricter policy than elsewhere, but it is Germany. It’s a bit frustrating, but that particular loose end will definitely be tied soon enough, after which Aoibhinn will be off to Germany for two years. Fortunately the start date of the fellowship is flexible. Congratulations to Aoibhinn!

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Classical Fluid Analogies for Schrödinger-Newton Systems

Posted in The Universe and Stuff with tags , , , , on July 16, 2025 by telescoper
Stock viscosity image: Photo by Fernando Serrano on Pexels.com

I thought I’d mention here a paper now on arXiv that I co-wrote with my PhD student Aoibhinn Gallagher. Here is the abstract:

The Schrödinger-Poisson formalism has found a number of applications in cosmology, particularly in describing the growth by gravitational instability of large-scale structure in a universe dominated by ultra-light scalar particles. Here we investigate the extent to which the behaviour of this and the more general case of a Schrödinger-Newton system, can be described in terms of classical fluid concepts such as viscosity and pressure. We also explore whether such systems can be described by a pseudo-Reynolds number as for classical viscous fluids. The conclusion we reach is that this is indeed possible, but with important restrictions to ensure physical consistency.

arXiv:2507.08583

It is based on work that his in her now-completed PhD thesis, along with another paper mentioned here. I have been interested for many years in the Schrödinger-Newton system (or, more specifically, the Schrödinger-Poisson system in the case where self-gravitational forces are involved). In its simplest form this involves a wave-mechanical representation, in the form of an effective Schrödinger equation, of potential flow described classically by an Euler equation. More recently we got interested in the extent to which such an approach could be used to model viscous fluids represented by a Navier-Stokes equation rather than an Euler equation. That was largely because the effective Planck constant that arises in this representation has the same dimensions as kinematic viscosity (but there’s more to it than that).

In the paper we explored a limited aspect of this, by looking at situations where there is no vorticity (so still a potential flow) but there is viscosity. There aren’t many examples of fluid flow in which there is viscosity but no vorticity, and most of those that do exist are about one-dimensional flow along channels or pipes with boundary conditions that don’t really apply to astrophysics, but one example we did look at in detail was the dissipiation of longitudinal waves in such a fluid.

One upshot of this work is that one can indeed describe some aspects of quantum-mechnical fluids such as ultra-light scalar matter in terms of classical fluid properties, such as viscosity, but you have to be careful. For more information, read the paper!

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Congratulations, Dr Gallagher!

Posted in Biographical, Maynooth, The Universe and Stuff with tags , , , on May 26, 2025 by telescoper

This week is off to a good start! This morning my postgraduate research student Aoibhinn Gallagher passed a viva voce examination on her thesis Cosmological Structure Formation Using Wave Mechanics. There will be a few formalities to deal with, some minor corrections to make, various forms to fill in, and the result has to be approved by the examination board, and so on, but basically that’s a job well done. Congratulations, Dr Gallagher!

Left to Right: Dr John Regan (internal examiner), Aoibhinn Gallagher (PhD candidate), and Prof. Cora Uhlemann (external examiner).

P.S. You can get an idea of some of the content of Aoibhinn’s thesis here.

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New Publication at the Open Journal of Astrophysics

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , on November 10, 2022 by telescoper

I’m delighted to be able to announce the 10000th paper this year, and 1000000th publication overall, at the Open Journal of Astrophysics!

That is counting in binary, of course. In base ten the  new paper at the 16th paper in Volume 5 (2022) as well as the 64th in all.

The latest publication is entitled “Evolution of Cosmic Voids in the Schrödinger-Poisson Formalism” and the authors are Aoibhinn Gallagher and Peter Coles (Who he? Ed) both of the Department of Theoretical Physics at Maynooth University. Obviously as author I played no role in the selection of referees or any other aspect of the editorial process.

Aoibhinn Gallagher – bonus marks for pronouncing both names correctly – is my first Maynooth PhD student and this is her first paper, of many I hope (and expect)! We’re already working on extensions of this approach to other aspects of large-scale structure. You can find some discussion of this general approach here.

Anyway, here is a screen grab of the overlay which includes the  abstract:

 

You can click on the image to make it larger should you wish to do so. You can find the officially accepted version of the paper on the arXiv here.

Here is a nice animated version of Figure 5 of the paper showing, for a 1D slice, the radial expansion of a spherically symmetric void (i.e. underdense region) using periodic boundary conditions:

The x-axis is in (scaled) comoving coordinates, i.e. expanding with the cosmological background, so that the global expansion is removed.  You can see that the void expands in these coordinates, so is expanding more quickly than the background, initially pushing matter into a dense ring around the rim of the empty void. That part of the evolution is just the same as for “normal” matter but in this case the wave-mechanical behaviour of the matter prevents it from being confined to a strongly-localized structure as well as affecting the subsequent expansion rate.

Of course in the real Universe, voids are not isolated like this but instead tend to push into each other, but we felt it was worth studying the single void case to understand the dynamics!

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