Archive for the The Universe and Stuff Category

R.I.P. Sir David Cox (1924-2022)

Posted in Biographical, mathematics, The Universe and Stuff with tags , , , , on January 21, 2022 by telescoper

I was saddened to hear a few days ago that the eminent statistician David Cox has passed away at the age of 97. I didn’t know Professor Cox personally – I met him only once, at a joint astronomy-statistics meeting at (I think) the Royal Astronomical Society back in the day – but I learnt a huge amount from books he co-wrote, despite the fact that he was of the frequentist persuasion. Three examples from my bookshelf are shown above.

I started my PhD DPhil in 1985 with virtually no formal study of statistics under my belt so I had to follow a steep learning curve and I was helped enormously by these books. I bought the book on Point Processes so as to understand some of the ideas being applied to galaxy clustering. It’s only a short book but it’s crammed with interesting ideas. Cox & Miller on Stochastic Processes is likewise a classic.

I know I’m not the only person in astrophysics whose career has been influenced by David Cox and I’m sure there are many other disciplines who have benefitted from his knowledge.

Among many other awards, David Cox was elected a Fellow of the Royal Society in 1973 and knighted in 1985.

Rest in peace Sir David Cox (1924-2022)

New Publication at the Open Journal of Astrophysics

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , on January 18, 2022 by telescoper

It’s a New Year and therefore a new Volume of the Open Journal of Astrophysics and it’s time to announce the first publication in it! This one is the 1st paper in Volume 5 (2022) and the 49th in all.

The latest publication is entitled Validating Synthetic Galaxy Catalogs for Dark Energy Science in the LSST Era and is written by Eve Kovacs of Argonne National Laboratory and 38 others on behalf of the LSST Dark Energy Science Collaboration.

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 arXiv version of the paper here. This is another one for the Cosmology and Nongalactic Astrophysics folder, which remains the most popular category so far on the Open Journal of Astrophysics site.

There is a little bit of a backlog in OJAp Towers owing to the Christmas break as some authors have been on leave and not doing their revisions, so I’d anticipate a few more papers in the next few weeks.

Congratulations to the 2022 RAS Award Winners!

Posted in The Universe and Stuff with tags , , , , , on January 15, 2022 by telescoper

Given all the doom and gloom going around I thought I’d take the opportunity to share some good news and also offer my public congratulations to the all the winners of medals and awards announced yesterday by the Royal Astronomical Society. Let me draw particular attention to the following subset, purely on the grounds that I know them and their work personally (and because they’ve all either been mentioned on this blog recently and/or been known to read it from time to time and/or have recently published in the Open Journal of Astrophysics and/or are on the Editorial Board thereof).

First, the Gold Medal goes to Professor George Efstathiou of Cambridge University a true giant of cosmology (metaphorically speaking of course – I’m actually taller than him):

I’m looking forward to George receiving his medal so he can tell us what kind of chocolate is inside.

Second, Professor Alan Heavens of South Kensington Technical College Imperial College London who gets the Eddington Medal:

I should mention that among many other things Alan has worked extensively on the application of Bayesian methods to cosmological data.

Third, Professor Catherine Heymans of Edinburgh, Astronomer Royal for Scotland, wins the Herschel medal;

Catherine was actually a PhD student supervised by Alan Heavens back in the day. I wonder if this is the first time that a PhD student/supervisor combination has won RAS medals in the same year?

Correction: I’m now told that Catherine actually did her PhD in Oxford supervised by Lance Miller so I withdraw the question.

And last but by no means least we have Professor Pedro Gil Ferreira who will give this year’s Gerald Whitrow lecture:

Two interesting facts about Pedro: (i) a direct English translation of “Pedro Ferreira” would be “Peter Smith”; and (ii) he is a member of the Editorial Board of the Open Journal of Astrophysics.

Congratulations to them and indeed to all the winners of awards and medals, a complete list of whom may be found here.

P.S. It suddenly struck me when I saw the announcements yesterday evening that it’s now two years since I last attended the RAS Ordinary Meeting in person or the RAS Club Dinner. Let’s hope these can start again reasonably soon.

The Largest Map of the Universe

Posted in The Universe and Stuff with tags , , , on January 14, 2022 by telescoper

Now I’m going to have to update the bit of my popular talks (e.g this one) about `Mapping the Universe’!

After just seven months of operations of the Dark Energy Spectroscopic Instrument (DESI) we now have the largest galaxy redshift survey – and it’s only about 10% of the way through its 5-year programme. Currently mapping the positions of about 7.5 million galaxies, the map will contain over 35 million by the time the survey is complete. Even now it is larger than all previous spectroscopic galaxy redshift surveys put together. The speed of DESI is accounted for by its use of 5000 robotically-positioned fibre-optic cables that can generate spectra of thousands of galaxy from a single pointing of the 4-m telescope on which it is mounted.

You can read more about the latest results from DESI here. I’ll just whet your appetite with this groovy animated picture:

DESI’s three-dimensional “CT scan” of the Universe. We are at in the lower left, looking out over 5 billion light years in the direction of the constellation Virgo. As the video progresses, the perspective sweeps toward the constellation Bootes. Each colored point represents a galaxy; gravity has pulled the galaxies into a “cosmic web” of dense clusters, filaments and voids. (Credit: D. Schlegel/Berkeley Lab using data from DESI)

The twinkling effect arises from the fact that you are viewing different thin slices through the 3D distribution. The dark sections that appear and disappear from time to time are just bits not yet included in the survey.

For those of you not familiar with astronomical distance measurements, 1500 megaparsecs = 1.5 Gigaparsecs = 4.5 billion light years (approximately), so this map is not only mapping the spatial distribution of galaxies but also how this distribution has evolved with cosmic time over billions of years.

ERC Starting Grant Statistics

Posted in Politics, Science Politics, The Universe and Stuff with tags , , , , , on January 10, 2022 by telescoper

Today the European Research Council (ERC) announced the first round of winners of Starting Grants under the new Horizon Europe programme. The results make for interesting reading. Some 397 grants were awarded worth a total of €619 million, i.e. about €1.5 million each on average, all intended for researchers in the early stages of their careers. A complete list of award winners can be found in this PDF document. Congratulations to all of them!

Here is the breakdown by host country:

You will see that Ireland has secured 8 (half in social sciences & humanities, and half in science). That’s not bad for a small country, and is comparable with Denmark, Norway and Finland. The only two funded in Physical Sciences & Engineering in Ireland are both at the University of Limerick.

The big shock, however, is that the number of grants to be hosted in the UK is down sharply on previous Starter Grant rounds. In previous years that I can remember the UK was at the top of the awards table. Now top spot goes to Germany, with the UK in third place, only just above the Netherlands. I wonder what the reason could be for that?

You might be surprised that the UK is listed at all because it is not in the EU has not signed an association agreement with the European Union. Switzerland, also not in the EU, has been awarded 28 grants but these are not eligible for funding because negotiations on association have ended without a signature. According to the ERC website:

As a result, host institutions established in Switzerland are not eligible for funding. Exceptionally for this call, since it was already closed before the termination of the negotiations between the EU and Switzerland, the proposals submitted with Swiss host institutions and which have been selected for funding may remain eligible if their host institution is replaced with a legal entity established in an eligible country.

This looks like a cue for other institutions to start poaching! Israel and Norway are non-EU countries have agreements in place.

The situation with the UK, as far as I understand it, is that negotiations towards an association agreement are currently snarled up with issues surrounding the Northern Ireland Protocol component of the UK’s withdrawal agreement from the European Union. If an agreement is signed before contracts have to be issued (in April) then the grants to UK institutions will be funded by the EU. If not then not.

In addition, successful applicants established in a country in the process of associating to Horizon Europe will not be treated as established in an associated country if the association agreement does not apply by the time of the signature of the grant agreement. 

In this case, however, the UK Government will fund these through the UKRI budget. So they say.

On the other hand, these grants are portable and some winners may decided to change host institution to avoid any uncertainty. Cue some more poaching?

Another thing that is striking is that although 46 UK institutions are intended hosts for such funding, only 12 of the grantees have UK nationality.

It follows that many of the UK’s grantees are from elsewhere, either in the EU or outside. It is possible under this scheme for awardees to relocate to institutions in member countries from non-member countries, which accounts for the large number of “Others” in the plot.

Notice the opposite applies to Italy: there are 58 Italian grantees but only 28 grants will be hosted in Italy.

Here is the breakdown by gender:

Anyway, you can read more about the statistics in this PDF document here.

Webb Deployment

Posted in Biographical, The Universe and Stuff with tags on January 8, 2022 by telescoper

I’ve been busy all afternoon supervising an online examination and I’m now about to cook my dinner, which means I haven’t got time to post anything much but I will pass on the very welcome news that the James Webb Space Telescope has now completed the lengthy sequence of operations that were required to deploy a large sunshield, the primary and secondary mirrors and other bits and bobs needed to turn it into a proper observatory rather than just a basket of deployables. The whole thing should now look something like this:

Artists impression of Webb (with, by the look of it, a bit of the Cosmic Web)

There were over 300 potential single-point failures in this sequence so these last couple of weeks have been as stressful as the launch. Now commissioning work can begin.

This all gives me the excuse to have a celebratory drink just like I did on Christmas Day. Cheers!

A Piece of Euclid

Posted in Biographical, Euclid, Maynooth, The Universe and Stuff with tags , , on January 6, 2022 by telescoper

Fame at last! A colleague from the Department of Theoretical Physics at Maynooth University told me the above piece appeared in today’s Irish Times so I rushed out and bought the paper. My rapture was rapidly modified however when I discovered that my name was given incorrectly (as Cole instead of Coles), but that was to some extent offset by the amusement it would give my colleagues to see me described as an “Experiment Physicist”. These two slips are now corrected in the online version of the article which you can find here.

I was quite surprised by the sudden appearance of the article today because I spoke to the writer, Seán Duke, about Euclid well over a year ago (May 2020). That’s the reason that some things are a bit out of date. For example, the launch of Euclid will now not take place until the first quarter of 2023. Also the piece states that the largest telescope in space is the Hubble Space Telescope (HST) which is no longer the case (as of Christmas Day 2021…).

I’ll leave it as an exercise for the student to spot any other errors. Please feel free to point them out through the Comments Box. If you’re not banned, that is…

A Time For Perihelion

Posted in The Universe and Stuff on January 4, 2022 by telescoper

Earth’s elliptical orbit viewed at an angle (which makes it look more eccentric than it is – in reality is very nearly circular).

According to my new RAS Diary,  today (Tuesday 4th January 2022) at approximately 06:55 GMT the Earth reaches at the point on its orbit which which it is at its closest to the Sun, i.e. at its perihelion. At this time the distance from the Sun’s centre to Earth’s centre will be  147,105,052 km. This year, aphelion (the furthest distance from the Sun) is at 08:11 GMT on July 4th 2022 at which point the centre of the Earth will be 152,098,455  km from the centre of the Sun. You can find a list of times and dates of perihelion and aphelion for future years here.

At perihelion the speed of the Earth in its orbit around the Sun is greater than at aphelion (about 30.287 km/s versus 29.291 km/s). This difference, caused by the Earth’s orbital eccentricity, contributes to the difference between mean time and solar time I blogged about when discussing the Winter Solstice a couple of weeks ago.

It surprises me how many people think that the existence of the seasons has something to do with the variation of the Earth’s distance from the Sun as it moves in its orbit. The fact that perihelion occurs in the depth of winter should convince anyone living in the Northern hemisphere that this just can’t be the case, as should the fact that it’s summer in the Southern hemisphere while it is winter in the North.

The real reason for the existence of seasons is the tilt of the Earth’s axis of rotation. I used to do a little demonstration with a torch (flashlight to American readers) to illustrate this when I taught first-year astrophysics. If you shine a torch horizontally at a piece of card it will illuminate a patch of the card. Keep the torch at the same distance but tilt the card and you will see the illuminated patch increase in size. The torch is radiating the same amount of energy but in the second case that energy is spread over a larger area than in the first. This means that the energy per unit area incident on the card is decreases when the card is tilted. It is that which is responsible for winter being colder than summer. In the summer the sun is higher in the sky (on average) than in winter. From this argument you can infer that the winter solstice not the perihelion, is the relevant astronomical indicator of winter.

That is not to say that the shape of the Earth’s orbit has no effect on temperatures. It may, for example, contribute to the summer in the Southern hemisphere being hotter than in the North, although it is not the only effect. The Earth’s surface possesses a significant North-South asymmetry: there is a much larger fraction of ocean in the Southern hemisphere, for example, which could be responsible for moderating any differences in temperature due to insolation. The climate is a non-linear system that involves circulating air and ocean currents that respond in complicated ways and on different timescales not just to insolation but to many other parameters, including atmospheric composition (especially the amount of water vapour).

The dates when Earth reaches the extreme points on its orbit (apsides) are not fixed because of the variations in its orbital eccentricity so, in the short-term, the dates can vary up to 2 days from one year to another. The perihelion distance varies slightly from year to year too; it’s slightly greater this year than last year, for example.

There is however a long-term trend for perihelion to occur later in the year. For example, in 1246, the December Solstice (Winter Solstice for the Northern Hemisphere) was on the same day as the Earth’s perihelion. Since then, the perihelion and aphelion dates have drifted by an average of one day every 58 years and this trend will continue. This means that by the year 6430 the timing of the perihelion and the March Equinox will coincide, although I will probably have retired by then…

A Citation Landmark

Posted in Open Access, The Universe and Stuff with tags , , on December 31, 2021 by telescoper

Just over a week ago I posted an item about the citations garnered by papers in the Open Journal of Astrophysics in the course of which I speculated on whether we would reach the 1000 mark before the end of 2021. Well, I checked on the NASA/ASD system today and it seems we have just made it:

There is still one paper we have published but not yet listed on ADS so the real number might be a little higher. It’s also possible that the figure will dip below a thousand again, at least for a short time. That is because ADS sometimes counts the citations to a published paper and to its preprint separately thus causing some duplication; when the issue is finally resolved the number of citations can go down.

Anyway, that’s a nice note to end the year on. Tomorrow we start with Volume 5 (2022)!

R.I.P. Willy Kley (1958-2021)

Posted in Biographical, The Universe and Stuff with tags , , , on December 29, 2021 by telescoper

Once again it is my sad task to pass on news of the death of a colleague from the field of astrophysics. Prof. Dr. Wilhelm (“Willy”) Kley of the Institut für Astronomie & Astrophysik at the Universität Tübingen
in Germany passed away suddenly on 21st December 2021, at the age of 63.

Here is the official announcement (in German) from his institution:

Willy Kley was a computational astrophysicist who worked on accretion processes, especially in the context of the formation of planets and planetary systems. I knew him a little personally, as he was for a time in the Astronomy Unit at Queen Mary & Westfield College (as it was then called) at the same time I was there. He worked with the group led by John Papaloizou, alongside Richard Nelson and others, and I was working on cosmology, so we didn’t work together, but I did get to know him a bit and had a number of interesting discussions. He was a very nice man as well as a first-rate scientist. Looking at his (extensive) publication list it seems that he continued to collaborate with former QMW colleagues after his return to Germany in 2000.

His death was unexpected – I believe he suffered a heart attack – and I’m sure the news will come as a shock to many of his friends and collaborators. To them, and to his family, I send heartfelt condolences.