Here’s a little video update to accompany the news that, as of yesterday (28th July), the European Space Agency’s Euclid spacecraft has reached its orbit around L2, the second Lagrange Point of the Earth-Sun system:
More news is on the way. Commissioning of the instruments is now complete and the telescope is in focus. On Monday 31st July, ESA will release the first actual images from the Euclid telescope!
Stay tuned here.
The rate of publication at the Open Journal of Astrophysics has now reached the point at which I think I’ll have to limit myself to weekly updates here rather than announcing every paper as it appears. We still announce individual papers on social media of course, meaning Mastodon, Facebook and the platform formerly known as Twitter…
This week we have published four papers which I now present to you here. These four take the count in Volume 6 (2023) up to 31 and the total published by OJAp up to 96. I speculated earlier this year that we might reach 100 before the end of 2023, now it looks certain we will reach the century mark as early as August! It is gratifying to see the range of papers published increasing, with all four of these in different categories.
In chronological order, the four papers published this week, with their overlays, are as follows. You can click on the images of the overlays to make them larger should you wish to do so.
First one up is “M-σ relations across cosmic time” by David Garofalo (1), Damian J. Christian (2), Chase Hames (1), Max North (3), Keegan Thottam (1) & Alisaie Eckelbarger (1). The author affiliations are: (1) Department of Physics, Kennesaw State University, USA; (2) Department of Physics and Astronomy, California State University, Northridge, USA; (3) Department of Information Systems, Kennesaw State University, USA. This is a discussion of the relationship between black hole mass and stellar velocity dispersion discovered in low redshift galaxies and its evolution with cosmic time. The paper was published on 25th July, is in the folder marked Astrophysics of Galaxies and can be found here.
Here is a screen grab of the overlay, which includes the abstract:
You can find the officially accepted version of the paper on the arXiv here.
The second paper to announce is “The fastest stars in the Galaxy” by Kareem El-Badry et al. (21 authors. This one is the fourth item in the folder marked Solar and Stellar Astrophysics and it reports the spectroscopic discovery of 6 new “runaway” stars, probably the surviving members of binary star systems in which one star exploded in a Type 1a supernova. The paper was published on 27th July 2023 and you can see the overlay here:
The accepted version of this paper can be found on the arXiv here.
The next paper is in the Earth and Planetary Astrophysics folder. It is in fact only the second paper we have published in that area. It is entitled “WHFast512: A symplectic N-body integrator for planetary systems optimized with AVX512 instructions” by Pejvak Javaheri & Hanno Rein (University of Toronto, Canada) and Daniel Tamayo (Harvey Mudd College, USA). This paper presents a fast direct N-body integrator for gravitational systems, and demonstrates it using a 40 Gyr integration of the Solar System.
Here is the overlay:
You can find the full text for this one on the arXiv here.
Last but by no means least, published yesterday (29th July), we have a paper that asks the question “Can Einstein (rings) surf Gravitational Waves?” by Leonardo Giani, Cullan Howlett and Tamara M. Davis of the University of Queensland, Australia. The primary classification for this one is Cosmology and Nongalactic Astrophysics and it discusses the possible effect(s) of gravitational waves on gravitational lensing observations.
You can click on the image of the overlay to make it larger should you wish to do so. You can find the officially accepted version of the paper on the arXiv here.
Yesterday I was tidying up a bit and came across the old notebooks I used when I was a research student. As I suppose is the case with everyone else, there’s quite a lot in them that never went anywhere. If you can read the example above, about 3/4 of the way down the right-hand page I left a note saying “This is a pointless task”. I can’t remember if that referred to that particular integral or my research in general!
Some people who have seen this picture remarked on the size of my integral signs. That’s because I had to do quite a lot of integrals with complicated integrands, so I got into the habit of drawing big integral signs as a prelude to writing down what I assumed would be a horrible formula.
The way I worked in those days (1985-88) was to do a lot of rough scribblings on scrap paper. When I got to something I thought was promising I would write up a “neat” version in the notebook and throw away the workings. I know younger folks these days do most of their work on a screen but, as an old fogey, I still write a lot down on paper or on a blackboard. I didn’t have my own blackboard when I was a PhD student, but I did have plenty of notebooks – most of which I have kept. I think that I’ll always find an essential part of the mathematical thought process involves a pen or piece of chalk in my hand, moving around and guiding my brain.
Looking through these books I remember that I also wrote down ideas for follow-up projects. I managed to do very few of these, but some were done by other people elsewhere independently of me, so at least they were reasonable ideas!
This is outside my usual areas, but there’s a new paper on arXiv which, if verified, could be extremely important. It’s called The First Room-Temperature Ambient-Pressure Superconductor and it is written by three scientists based in Korea. High temperature superconductivity has been, er, a hot topic for some years. One must be cautious because (as far as I am aware) the article has not yet been refereed, but is this a breakthrough?
Here is the abstract:
It seems to me that 400K is a bit hot for a room, but the point is that the material behaves as a superconductor (i.e. zero resistivity) for T < Tc so cooler rooms would do! The current definition of “high temperature” is Tc > 77K which is much lower than the Tc = 400 K stated here.
Here’s part of a figure from the paper showing (right) the material LK-99 and its structure (left):
I’m not an expert, but it looks like the material involved is neither particularly expensive nor particularly complicated so it should be relatively easy to determine whether these results are reproducible.
Comments from experts are welcome!
Time to announce yet another new paper at the Open Journal of Astrophysics. This one was published yesterday, on 21st July 2023.
The latest paper is the 27th so far in Volume 6 (2023) and the 92nd in all. The authors are Sohan Ghodla, Richard Easther, M.M. Briel and J.J. Eldridge, all of the University of Auckland in New Zealand.
The primary classification for this paper is Cosmology and Nongalactic Astrophysics and its title is “Observational implications of cosmologically coupled black holes”. The paper elucidates some of the consequences of a suggestion that the interaction between black holes and the global properties of space-time underlying explanation for dark energy. The key result is that the existence of cosmologically-coupled black holes implies a much larger rate of black-hole merger events than is observed.
The papers to which this is a response are mentioned here. For reference ,these earlier works were published in The Astrophysical Journal and The Astrophysical Journal Letters. There is also a detailed twitter thread about this paper by Richard Easter, posted when it was submitted as a preprint to the arXiv last month:
Anyway, here is a screen grab of the overlay of the published version which includes the abstract:
You can click on the image of the overlay to make it larger should you wish to do so. You can find the officially accepted version of the paper on the arXiv here.
Time for an update at the Open Journal of Astrophysics. Owing to a well-deserved holiday by a member of the OJAp team, we were unable to register DOIs and associated metadata for a couple of weeks so refrained from announcing new papers during this period while other functions of the journal continued. Anyway, this week we have caught up with the backlog of four papers, which I now present to you here, all published on 17th July 2023. These four take the count in Volume 6 (2023) up to 26 and the total published by OJAp up to 91.
In no particular order, the four papers published this week, with their overlays, are as follows. You can click on the images of the overlays to make them larger should you wish to do so.
“Large-scale power loss in ground-based CMB mapmaking” by Sigurd Naess (Oslo, Norway) and Thibaut Louis (Saclay, France). This one is a discussion of the possible biases introduced by using a data model to create sky maps of CMB temperature fluctuations and is in the folder marked Instrumentation and Methods for Astrophysics.
Here is a screen grab of the overlay, which includes the abstract:
You can find the officially accepted version of the paper on the arXiv here.
The primary classification for the next paper paper is Cosmology and Nongalactic Astrophysics and its title is “”The cumulant generating function as a novel observable to cumulate weak lensing information”. The authors are Aoife Boyle (Saclay, France), Alexandre Barthelemy (LMU, Germany), Sandrine Codis (Saclay, France), Cora Uhlemann (Newcastle, UK) & Oliver Friedrich (LMU, Germany). The paper explores the use of the cumulant generating function (CGF), from which the probability density function (PDF) can be obtained, in the context of weak gravitational lensing information.
You can click on the image of the overlay to make it larger should you wish to do so. You can find the officially accepted version of the paper on the arXiv here.
Also in the folder marked Cosmology and Nongalactic Astrophysics is the third paper “Cosmology with 6 parameters in the Stage-IV era: efficient marginalisation over nuisance parameters” by B. Hadzhiyska (Berkeley, USA), K. Wolz (Trieste, Italy), S. Azzoni (Oxford, UK; Tokyo, Japan), D. Alonso (Oxford, UK), C. García-García (Oxford, UK), J. Ruiz-Zapatero (Oxford, UK) and A. Slosar (Tokyo, Japan). This presents an efficient analytical method to speed up marginalization over nuisance parameters introduced to model systematic effects in large-scale structure data.
Here is a screen grab of the overlay which includes the abstract:
You can find the officially accepted version of the paper on the arXiv here.
The final paper in this quartet, also in Cosmology and Nongalactic Astrophysics, is “Modeling the Galaxy Distribution in Clusters using Halo Cores” by D. Korytov, E. Rangel, L. Bleem, N. Frontiere, S. Habib, K. Heitmann, J. Hollowed, and A. Pope (all of the Argonne National Laboratory, USA). This presents a new method to speed up numerical simulations using a method of simplifying the handling of substructure in galaxy clusters using halo ‘core-tracking’.
The overlay of this one is here:
You can find the officially accepted version of the paper on the arXiv here.
I saw this little movie on the ESA Update page for Euclid and couldn’t resist sharing it here. It’s a montage of images from the Canada-France Hawaii Telescope (CFHT); the object you see moving upwards in the centre of the frame is none other than the Euclid spacecraft, hurtling towards its destination at the 2nd Lagrange Point. You will see other moving objects. I’m not sure what they are but the field is in the ecliptic plane so they’re likely to be small solar system objects, probably asteroids.
Incidentally, people keep asking me for updates about Euclid. Although I am privy to the regular updates available to members of the Euclid Consortium, I am not allowed to publish anything on here that’s not already in the public domain nor would I want to, lest anyone think I would presume to speak on behalf of either ESA or the Euclid Consortium via the medium of a personal blog. You can follow the official updates here from people who actually understand everything that is going on!
I will just say that all the key steps so far – a critical orbit manoeuvre needed to get into the correct trajectory for L2, a temporary rotation of the spacecraft to allow it to heat up and to allow residual gas to evaporate, deployment of the high-gain antenna (essential to send data back to Earth), and the switching on of the two instruments (NISP and VIS) – have taken place in good order. There is however a long way to go before everything is tested, verified, calibrated and ready for action. It’s a very busy time for the engineers and instrumentalists; we just need to give them the time they need to work their technical magic!
I’ve been meaning to post about for some time about the use of telescopes all around the world that reside in observatories on lands previously and/or presently occupied by indigenous peoples. The creation of these astronomical facilities has been accompanied by neglect (and sometimes violent displacement) of tribal communities native to the land on which they now stand. Though we exploit native lands for science, the astronomical community makes little reference to the people who are directly impacted by the advancement of astronomy through colonialism of this sort.
I know I’m not alone in thinking that, at the very least as a community we should do much more to acknowledge our use of astronomical facilities built on land that in many cases was basically “stolen” by colonial settlers. There was a talk about this issue at the recent Euclid Consortium Meeting in Copenhagen, and it came up at the National Astronomy Meeting in Cardiff in the context of the broad issue of the decolonization of astronomy.
Anyway, just for a start I have included here a small gallery of images of modern astronomical observatories of various kinds, with captions giving the names not of the observatory, but of the indigenous peoples upon whose land it is built:
There are many more than these, but hopefully you get the point. The question is: what to do about it?
I was in a meeting this morning at which it was mentioned that the recent launch of the Euclid satellite has generated quite a lot of publicity in the news media for Maynooth University. There’s a piece in the Sunday Times (Ireland Edition), another in Silicon Republic, and an online feature for RTÉ Brainstorm as well as a radio segment on Morning Ireland and another on NewsTalk.
Maynooth University plugged these items in on the “Maynooth in the News” feed on its main webpage, along with many other items that show the University in a good light.
Conspicuous by its absence from that feed, however, is the biggest story surrounding Maynooth University in recent days, namely the appalling decision by the President to scrap elections to the Governing Authority of the University in favour of having representatives chosen only by the President. This is just one example of the increasingly intransigent and authoritarian management of the University. Can anyone justify the complete disenfranchisement of the staff of the University from the Governance of the university? Or that an Executive body should select the Board to which it is supposed to be accountable?
I know I’m not the only person employed by this University who thinks this decision is a terrible one – my Union, IFUT is strongly opposed- but it has been already been imposed and now we have no say. At least you can read about, e.g. here in the Times Higher.
One story you can’t read about however concerns the outcomes of Maynooth University’s “Staff Climate and Culture Survey” which was carried out in 2022 with the promise made to participants that results would be published in early 2023. No such results were ever communicated to staff and all mention of this survey has been wiped off the University’s web pages. I don’t know why this happened, but I venture to suggest that if the results had been good the Maynooth publicity team would not have hesitated to publish them.
Since the Management of Maynooth University has chosen to close off any internal channels by which academic and other staff can communicate their views, it seems that the only means of communication open to us is via the external media. Perhaps the Times Higher will run a story on the Curious Case of the Missing Staff Survey?
The Euclid spacecraft launched over a week ago so so here’s a short video explaining its trajectory and what it will do over the next weeks and months.
In the Dark 