Archive for April, 2024

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DESI Year 1 Results: Baryon Acoustic Oscillations

Posted in Barcelona, Euclid, The Universe and Stuff with tags , , , , on April 4, 2024 by telescoper

There has been a lot of excitement around the ICCUB today – the press have been here and everything – ahead of the release of the Year 1 results from the Dark Energy Spectroscopic Instrument (DESI). The press release from the Lawrence Berkeley Laboratory in California can be found here.

The papers were just released at 5pm CEST and can be found here. The key results pertain to Baryon Acoustic Oscillations (BAOs) which can be used to track the expansion rate and geometry of the Universe. This is one of the techniques that will be used by Euclid.

There’s a lot of technical information to go through and I have to leave fairly soon. Fortunately we have seminar tomorrow that will explain everything at a level I can understand:

I will update this post with a bit more after the talk, but for the time being I direct you to the high-level cosmological implications are discussed in this paper (which is Paper VI from DESI).

If your main interest is in the Hubble Tension then I direct you to this Figure:

Depending on the other data sets included, the value obtained is around 68.5 ± 0.7 in the usual units, closer to the (lower) Planck CMB value than the (higher) Supernovae values but not exactly in agreement; the error bars are quite small too.

You might want to read my thoughts about distances estimated from angular diameters compared with distances measured using luminosity distances here.

If you’re wondering whether there is any evidence for departures from the standard cosmology, another pertinent comment is:

In summary, DESI data, both alone and in combination with other cosmological probes, do not show any evidence for a constant equation of state parameter different from −1 when a flat wCDM model is assumed.

DESI 2024 VI: Cosmological Constraints from the Measurements of Baryon Acoustic Oscillations

More complicated models of time-varying dark energy might work, but there’s no strong evidence from the current data.

That’s all from me for now, but feel free to comment through the box below with any hot takes!

UPDATE: As expected there has been quite a lot of press coverage about this – see the examples below – mostly concentrating on the alleged evidence for “new physics”. Personally I think the old physics is fine!

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Open Journal of Astrophysics Update

Posted in OJAp Papers, Open Access with tags , , , , , on April 4, 2024 by telescoper

I’ve just noticed that my post earlier in the week about changes to the publication system at the Open Journal of Astrophysics is dated April 1st. I can assure you it wasn’t meant as a joke! Anyway, the integration with Crossref is now complete and I’ve started clearing the backlog of papers waiting to be published. I would say normal service has been resumed, but the idea is to make the process faster and more reliable than before so it’s hopefully a return but to better-than-normal service.

I want first of all to thank the people at Maynooth University Library, Crossref, and Scholastica for helping us figure out the issue and solve it. We would no doubt have got there faster were it not for the intervention of the Easter break, but in any case it has only required a pause of publication for a couple of weeks.

I’ll resume the regular weekly updates at the weekend. However, one paper got snarled up when we ran into a problem. Although published on 20th March, it was never properly registered with Crossref. The only way I could think of to sort out the issue with this one was to start it again, which I did this morning, and it is now published though I kept the publication date as 20th March.

This paper, by Yingtian Chen and Oleg Gnedin of the University of Michigan, is the 21st paper to be published in Volume 7 and the 136th altogether. It is a study of kinematic, chemical and age data of globular clusters from Gaia yielding clues to how the Milky Way Galaxy assembled. You can read the article on arXiv directly here.

You will note the new format of DOI on the overlay. Nothing else has changed that’s visible to the reader.

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Two Poems by Sir Thomas Wyatt

Posted in History, Poetry with tags , , , , , , , on April 3, 2024 by telescoper

Another character who appears in Hilary Mantel’s novel Wolf Hall is Sir Thomas Wyatt (1503-1542) who was a diplomat and member of the Court of Henry VIII, as well as being a fine poet. I thought I would post two of his famous poems.

The first is a sonnet, written some time in the 1530s, is ostensibly a (loose) translation of Petrarch’s Una Candida Cerva and thus one of the first examples of a Petrarchan Sonnet written in English. That makes it interesting in its own right, but many people think that it is actually about Anne Boleyn. The use of hunting as a metaphor for courtly love was widespread and, despite being married, Wyatt seems to have had his eye on Anne Boleyn. As far as is known, however, they didn’t have a sexual relationship. Wyatt wisely backed off when he realized he was competing with Henry VIII (thinly disguised as “Caesar”) in the penultimate line; Noli me tangere means “do not touch me” in Latin.

Whoso list to hunt, I know where is an hind,
But as for me, hélas, I may no more.
The vain travail hath wearied me so sore,
I am of them that farthest cometh behind.
Yet may I by no means my wearied mind
Draw from the deer, but as she fleeth afore
Fainting I follow. I leave off therefore,
Sithens in a net I seek to hold the wind.
Who list her hunt, I put him out of doubt,
As well as I may spend his time in vain.
And graven with diamonds in letters plain
There is written, her fair neck round about:
Noli me tangere, for Caesar’s I am,
And wild for to hold, though I seem tame.

Wyatt was in fact confined to the Tower of London in 1536 on suspicion of having committed adultery with Anne Boleyn; adultery with the King’s wife was considered treason, a capital offence. While in the Tower, where he witnessed executions, possibly including that of Anne Boleyn herself and others accused of treason with her, he wrote this other famous poem

Who list his wealth and ease retain,
Himself let him unknown contain.
Press not too fast in at that gate
Where the return stands by disdain,
For sure, circa Regna tonat.

The high mountains are blasted oft
When the low valley is mild and soft.
Fortune with Health stands at debate.
The fall is grievous from aloft.
And sure, circa Regna tonat.

These bloody days have broken my heart.
My lust, my youth did them depart,
And blind desire of estate.
Who hastes to climb seeks to revert.
Of truth, circa Regna tonat.

The bell tower showed me such sight
That in my head sticks day and night.
There did I learn out of a grate,
For all favour, glory, or might,
That yet circa Regna tonat.

By proof, I say, there did I learn:
Wit helpeth not defence too yerne,
Of innocency to plead or prate.
Bear low, therefore, give God the stern,
For sure, circa Regna tonat.

The repeated Latin phrase circa Regna tonat is usually translated “Thunder rolls around the Throne”, a reference to the dangerous temperament of the King.

Wyatt was not executed in 1536, but released after the intervention of none other than Thomas Cromwell. It seems he had a habit of sailing rather close to the wind, and was in and out of trouble with the King, being charged again with treason in 1541 and again released. He died, apparently of natural causes, in 1541, at the age of 39.

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John Henry – Big Bill Broonzy

Posted in Music with tags , , , , , on April 2, 2024 by telescoper

I’ve been meaning to post this track for some time but for some reason haven’t got around to it until now. It was recorded in Germany in 1951 and is a solo performance by legendary guitarist, blues singer and guitarist Big Bill Broonzy. The song, often called the Ballad of John Henry, tells the story of the folk hero John Henry, a man whose job was to use a 12lb hammer drive a steel drill into a rock to make holes for explosives to blast the rock in constructing a railroad tunnel. In the legend, John Henry is pitted against a steam-powered drill. He beats the machine, but is exhausted by his efforts and dies with his hammer in his hand.

By the way, you will hear reference in the song to a “shaker”. This was a man whose job it was to hold the drill – an object like a chisel – against the rock while it was struck by the hammer, and move it about to loosen the rock around it. I dread to think what happened if the hammerman missed the drill.

The historical facts around the location of the story of John Henry and indeed the identity of the hero are open to debate, but it’s a wonderful song and this is a brilliant and very characteristic performance of the song by Big Bill Broonzy whose singing, playing, and announcement to the song, will bring it all back to anyone lucky enough to hear him in the flesh. Bill Broonzy was on a European tour at the time this record was made, and I have back at home a very old LP of him singing and playing at the Dancing Slipper in West Bridgford, in Nottingham. I also have a copy of the album from which this performance is taken, the other side of which is by Graham Bell and his Australian Jazz Band. The full introduction to John Henry begins with Bill Broonzy saying rather sardonically “Thank you. Thank you. Thank you. I’m glad to be here too, don’t think I ain’t” before the rest of it that you hear.

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Changes at the Open Journal of Astrophysics

Posted in Maynooth, Open Access with tags , , , , , , , on April 1, 2024 by telescoper

Regular readers of this blog – both of them – will have noticed that I haven’t posted any new publications from the Open Journal of Astrophysics for a couple of weeks. The reason for this is that we are switching to a new system of publishing that automatically integrates the Scholastica platform with Crossref, the system that (among many other things) keeps track of citations to published articles.

Up to now, I have had to prepare manually an XML file containing the metadata for each paper for upload, then send it to a colleague to register with Crossref. There are two problems with this. One is that transcribing the information from each overlay is prone to errors (made by me), especially if there is a long author list. The other problem is that it is rather slow and inefficient, which wasn’t such a problem when we were only publishing a few papers, but now that we are handling much more it is taking up too much time.

The obvious solution is to cut out the middle man (i.e. me) and register everything with Crossref directly from our platform. That will ensure that what goes to Crossref will be exactly the same as on our website and it will go there much faster. Another advantage is that if there is an error on the platform, such as a spelling mistake in an author name, correcting it there will automatically update the metadata on Crossref. You have no idea how much time and frustration this will save. Up to now we have to raise a ticket with Crossref for their staff to make the change, which can take a while to complete.

Scholastica offers a way to do this integration, but it doesn’t work with our existing Digital Object Identifiers (DOIs), which have the format 10.21105/astro.1234.56789, because it doesn’t allow us to include the “astro” which we need it to do because we share the prefix (10.21105) with another journal, the Journal of Open Source Software and we need to keep the two separate; they use 10.21105/joss at the start of their DOIs. After much to-ing and fro-ing we were unable to persuade Scholastica to change their policy, so to use their integration we have been forced to change prefix. Fortunately, Maynooth University (which runs Maynooth Academic Publishing, the official publisher of OJAp) is registered to mint its own DOIs so we can switch to a new prefix (10.33232) and avoid potential problems with the old one.

This change seems straightforward but it requires Crossref to switch the “ownership” of the journal and give us permission to add new papers with the same journal title “The Open Journal of Astrophysics” from what is effect a new publisher. This is a straightforward process, but has been a bit slower than expected because of the Easter break. I expect it to be completed in a week or so, at the latest.

It is important to stress that this change only affects the DOIs and registration of new papers. Existing papers are not affected at all: they continue with the old DOIs. The DOI is meant to be a persistent identifier so this is as it should be. The name of our website domain (astro.theoj.org) remains unchanged too. In other words, nothing visible to authors will change except for the format of the DOIs and the fact we go from acceptance to publication even faster.

If al this seems rather boring, that’s because it is. But please bear with us while we complete this change. It’s definitely going to be worth it in the long run, for me if nobody else!

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Thomas Cromwell and his Prayer-Book

Posted in Art, History with tags , , , , , , on April 1, 2024 by telescoper
(1532-1533, Oil on Panel, 78.1 cm × 64.1 cm) by Hans Holbein the Younger – The Frick Collection, Public Domain, https://commons.wikimedia.org/w/index.php?curid=207764

The famous portrait of Thomas Cromwell by Hans Holbein the Younger shown above is in fact a copy; the original is lost. There is another copy in the National Portrait Gallery in London, but it’s not as good. The original was painted around 1533, during the period covered by the novel Wolf Hall (which I reviewed yesterday) and is mentioned in the book. Holbein is known for having sometimes painted excessively flattering portraits – most notably of Anne of Cleves – but he doesn’t seem to have done that here. Cromwell is portrayed as dour, stern-faced and more than a little scary. He probably wanted people to fear him, so wouldn’t have minded this.

As well as the nature of the likeness, the composition is interesting. The subject seems to be squashed into the frame, and hemmed in by the table that juts out towards the viewer. He is also looking out towards the viewer’s left, though not simply staring into space; his eyes are definitely focussed on something. I’m not sure what all this is intended to convey, except that the table carries an ornate prayer-book (the Book of Hours) as if to say “look, here’s a symbol of how devout this man is”.

Interesting, just last year scholars published research that argues that the copy of the Hardouyn Hours which can be found in the Library at Trinity College, Cambridge, is precisely the book depicted on the table. If so, it’s a rare and perhaps unique example of an artefact seen in a Tudor painting that survives to this day.

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