This post is a vague collection of things I regarded as moderately noteworthy this week, or interesting things which I found, read, or did during the course of the week. I’m not really sure anyone else would want to read it, but please feel free.
This week I finally closed out work on the updates to the parameter estimation data release for GWTC-2.1. It should be available next week, and will come with updated results for a larger set of events from GWTC-2, which we’ve reanalysed with the same waveforms and pipelines used for the new GWTC-2.1 and the GWTC-3 events.
Asimov gets plugins and more analysis types
Keeping on the subject of data analysis and parameter estimation, I’ve continued work on asimov, the framework I’ve lead the development of over the last couple of years to make it easier to automate a much larger number of analysis pipelines. It’s likely to be a little while before these make a release, but if you’re a gravitational wave person wanting to take advantage of our automation techniques, then watch this space! I’m also hopeful that in the near future I’ll have improved the code enough that it’s possible to automate and manage non-GW analyses with it too.
Some papers I found on the Arxiv which look interesting enough to read, or add to my reading list (sorry, it’s been a busy week!). As ever there were many interesting new papers, and this is just a selection which particuarly caught my eye. It’s in no way a judgement of quality!
Resonant strings & gravitational waves
Masses in the universe interact with gravitational waves in a way which is analogous to how charges interact with electromagnetic fields. This paper takes a closer look at how “closed classical strings” might interact with a gravitational wave, and what the gravitational wave would do to the string.
This one’s firmly one for the reading list; my understanding of a lot of the background on strings is a bit insufficient to get past the abstract for now!
Black holes as heat engines
This was another paper which caught my eye and lies in the realm of interesting bits of theory. This is one which links black holes, which we normally think of as a purely gravitational phenomenon, to classical thermodynamics. This is one of the bits of physics Stephen Hawking was famous for, and again is one of those things I should really know more about than I do. I also need to go and learn what a hyperbolically charged black hole is. Another one on the reading list.
GEO and KAGRA together
This paper discusses the joint observing run between two gravitational wave detectors which haven’t really seen their share of the limelight in the last couple of years. GEO is the dependable workhorse of detector development, which was built in a field in Germany by a collaboration of German and UK scientists. KAGRA is a detector in Japan which is both underground and cryogenic, and still being constructed. Right now neither can quite match the sensitivity of the LIGO and Virgo detectors, but this observing run, which was carried out after the main O3 runs had finished, is an important milestone for KAGRA. I’m writing an omnibus blog post about the O3 runs at the moment, which is why I came upon this paper again, which I’d overlooked a bit over the last few months.
Controls noise in suspensions for LIGO
Dealing with noise in measurements from ground-based detectors is a major part of how we improve the sensitivity of the detectors to gravitational waves, alongside improvements in the analysis. This paper discusses a new technique for reducing the coupling of vibrations in the ground around a detector into the data at low frequencies (10 to 20-Hz), which is a part of the spectrum where detectors are conventionally very noisy.
Virgo Detchar in O3
This one’s a bit of a beast, and is firmly on the to-read list, at 86 pages (though I’ll try and include it in the O3 megapost I mentioned above). Detector characterisation (Detchar) is a vital part of the process of detecting and analysing gravitational waves, and keeps on the earlier theme of noise. Detchar involves attempting to understand the sources of noise in the detector so that we can, as much as possible, mitigate their effects, either in the analysis or by making changes and upgrades to the detectors.
Mass ratio reversal in BBHs
This is another one of those papers which reminds me about holes in my knowledge. This time its about population synthesis, or understanding how the universe comes to have binary black hole systems which look like the ones we observe coalescing.
This paper discusses the distribution of spins within these systems, and reminds me that I really need to block-off some time to learn a lot more about this whole subject area.
Assessing gravitational wave detector networks
Gravitational wave detectors cost a lot of money to build, and so understanding how they behave before you do that is important. In order to measure the location of the source of a gravitational wave we also need a number of different detectors spread around the globe s a network. This paper introduces a new piece of software which is designed to improve the way that we simulate these networks in order to determine what improvements we would gain in our abilities to make detections and inferences on detected signals for a variety of different detector networks.
Primordial black holes
Primordial black holes are a possible target for gravitational wave detection if they coalesce in the same way as the stellar mass black holes which we routinely observe with current detectors. Primoridal black holes, however, are much lighter (and smaller), having been created very early in the life of the Universe, rather than through the collapse of stars. This paper tries to model the likely rate of coalescences between PBHs, and then look at our ability to detect them using a future gravitational wave detector, the Einstein Telescope, which may have the required sensitivity to observe them.
More black hole spins
Do supernovae “toss” the black holes they create around so that their spins are differently aligned to their progenitor stars? This paper argues that if the BBHs observed so far by GW detectors are the result of isolated binary formation then this likely does happen, but the mechanism by which it can happen remains unknown.
Software & Code
We’re working to set up some new compute machines in the department, which has given me a chance to play around with setting kubernetes up, and then trying to set htcondor on top of it. I feel like there’s an eventual blog post in it, but right now I’m mainly trying to get my head around a lot of new ideas.
Red Mars by Kim Stanley Robinson
I’ve found it especially difficult to finish books lately, so I was quite happy to have made the time to finally finish the last quarter of this book which I started reading late last summer… Red Mars covers around half a century of future (and present-alternative, now) time in which humanity starts the process of colonising Mars, and making early attempts to terraform it. There are ups and downs, and the book started with a general upbeatness which gradually withers as it goes on. I might post some more thoughts on it in the next few days if I can find the time, but I don’t want to say too much without being a bit more careful about giving away important plot points It’s the first of a trilogy, and going by how long it took me to finish the first volume, it might be a while until I get to the end. The ideas in the book are good, and overall it’s enjoyable, but I found it slow and hard going, which is a little unusual for me with hard sci-fi.
Beinn a’ Bheithir
I climbed Beinn a’ Bheithir with a friend this bank holiday Monday, re-establishing a tradition of Munroing on May Day (I climbed my first Munro properly on May Day 2018) which had been curtailed in 2020 and 2021 by lockdowns. The mountain is named after a Celtic thunder-breathing dragon. I only found this out after we climbed it, or I suspect I’d have spent a lot more time being exceptionally nerdy in the company of said friend. More to come on this in a later post.
I did Parkrun on Saturday. I’m not sure this really counts as noteworthy, but I’m pleased that I now seem to be consistently finishing Ruchill in under 20 minutes, which is nice, but just means that I now need a new target, which just feels like it’s going to involve a lot more pain.
MacTuff Sprint 2022
On Sunday I found myself in a very muddy field, and wasn’t even carrying a ball through it. I tried out an obstacle course race in Fife, got extremely muddy, and despite the name of the race, didn’t find myself doing a great deal of sprinting. I have a GoPro video which shows a lot of muddy water. I’ll try and write this up more at the weekend.
The third and final race / fast run of the week was the Bog & Burns series “Whangie Whizz”, which runs through the Whangie and over Auchineden Hill. This one also deserves a race report, but I got around in fairly decent time, but probably left gas in the tank a little long, and should have started out a bit faster to avoid being held back along the narrow track up to the Whangie. Another case of fairly fast ascent and overly cautious descent.Share Share Share