New Publication at the Open Journal of Astrophysics

With all the excitement of my first weekend in Sydney I completely forgot to post an update from the Open Journal of Astrophysics. In fact there is only one paper to report from last week, being  the 12th paper in Volume 7 (2024)  and the 127th altogether. This one was published on 9th February 2024 and is the first published from Down Under.

The title is “Galaxy Clusters Discovered via the Thermal Sunyaev-Zel’dovich Effect in the 500-square-degree SPTpol Survey” and it presents a catalogue of 689 galaxy clusters detected through the thermal Sunyaev-Zel’dovich using the dual-frequency polarization-sensitive camera SPTPol on the South Pole Telescope. This one is in the folder called Cosmology and NonGalactic Astrophysics.

This paper has lead author Lindsey Bleem  of the Argonne National Laboratory in the USA and has 127 other authors – too many to list individually here – but you can see them on the overlay below. I see quite a few names of people I know well!

Here is the overlay of the paper containing 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.

P.S. Incidentally, while I’m here I thought I’d share this little graphic I’ve generated (for other purposes) that shows how the rate of submissions to OJAp has increased over the last 5 years:

Two New Publications at the Open Journal of Astrophysics

As the first month of 2024 is now over, I thought I’d post an update relating to the  Open Journal of Astrophysics.  Since the last update we have published two papers, taking  the count in Volume 7 (2024) up to 9 (the total for January) and the total published by OJAp up to 124. We will have others soon, but I will be travelling for the first few days of February so the next update will be in a week or so.

Using our sophisticated forecasting algorithm, based on the first month of 2024 as input, I predict that we will publish around 9×12=108 papers in 2024, more than double last year’s total of 50.

Both the current papers discussed here are in the folder marked Cosmology and NonGalactic Astrophysics, our most popular category.

Anyway, the first paper of the most recent pair – published on January 30th – is “Capse.jl: efficient and auto-differentiable CMB power spectra emulation”, by Marco Bonici (INAF Milano, Italy & Waterloo, Canada), Federico Bianchini (Stanford, USA) and Jaime Ruiz-Zapatero (Oxford, UK). This paper presents an emulator for rapid and accurate prediction of Cosmic Microwave Background (CMB) temperature, polarization, and lensing angular power spectra, that works much faster than traditional methods. The code is written in Julia, in which language we are seeing an increasing number of submissions to OJAp.

Here is a screen grab of the overlay 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.

The second paper was published yesterday (31st January 2024) and has the title “Cosmological Inflation in N-Dimensional Gaussian Random Fields with Algorithmic Data Compression” which is a  study of inflationary models with Gaussian random potentials for multiple scalar fields, tracking the evolutionary trajectories numerically. The authors are Connor Painter and Emory Bunn, both the Physics Department at the University of Richmond, Virginia (USA). Ted Bunn (as he is usually known) is a longstanding member of the Editorial Board of the Open Journal of Astrophysics (and was thereby excluded from any involvement in the editorial process for this paper).

Here is a screen grab of the overlay 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.

Here Endeth the Update.

R.I.P. Arno Penzias (1933-2024)

Yesterday I heard the sad news of the death, at the age of 90, of American physicist and radio astronomer Arno Penzias.

I’ve used the above image hundreds of times in popular talks. It shows Robert W. Wilson (left) and Arno A. Penzias (right) standing in front of the famous horn antenna that (accidentally) discovered what we now know to be the cosmic microwave background, radiation left over after the Big Bang.

Penzias and Wilson made their historic measurements in 1964, published their results in 1965, and received the Nobel Prize for Physics in 1978. At the time of this experiment, the scientists were working at Bell Telephone Laboratories at Holmdel, New Jersey, on Project Echo. The antenna was built to receive radio signals bounced off a passive satellite in a low Earth orbit to check the feasibility of satellite radio communication. They found excess noise in their receiver, which was eventually identified as a relic of a time when the Universe was extremely hot. Coincidentally, the theory of this yet undiscovered radiation was being worked on by Bob Dicke and his group in Princeton at about the same time (and also in New Jersey). Discussions ensued, and the discovery paper by Penzias & Wilson appeared in the Astrophysical Journal in 1965 beside a paper by Dicke et al. giving the theoretical interpretation.

The discovery of the cosmic microwave background was probably the most important result in observational cosmology after that of the Hubble expansion and it paved the way for the establishment and further development of the Big Bang theory. One of the two discoverers of the CMB has now left us, leaving a priceless legacy.

Rest in peace, Arno Allan Penzias (1933-2024)

Three New Publications at the Open Journal of Astrophysics

As promised yesterday, it’s time for a roundup of the week’s business at the  Open Journal of Astrophysics. This past week we have published three papers, taking  the count in Volume 7 (2024) up to 4 and the total published by OJAp up to 119. There are quite a few more ready to go as people return from the Christmas break.

In chronological order, the three 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 “Prospects for studying the mass and gas in protoclusters with future CMB observations” by  Anna Gardner and Eric Baxter (Hawaii, USA), Srinivasan Raghunathan (NCSA, USA), Weiguang Cui (Edinburgh, UK), and Daniel Ceverino (Madrid, Spain). This paper, published on 17th January 2024, uses realistic hydrodynamical simulations to probe the ability of CMB Stage 4-like (CMB-S4) experiments to detect and characterize protoclusters via gravitational lensing and the Sunyaev-Zel’dovich effect. This paper is in the category of Cosmology and Nongalactic 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 second paper to announce is “SDSS J125417.98+274004.6: An X-ray Detected Minor Merger Dual AGN” and is by Marko Mićić, Brenna Wells, Olivia Holmes, and Jimmy Irwin (all of the University of Alabama, USA).  This presents the discovery of a dual AGN in a merger between the galaxy SDSS J125417.98+274004.6 and dwarf satellite, studied using X-ray observations from the Chandra satellite. The paper was also published on 18th January 2024 in the category Astrophysics of Galaxies . You can see the overlay here:

 

The accepted version of this paper can be found on the arXiv here.

The last paper of this batch is  entitled “Population III star formation: multiple gas phases prevent the use of an equation of state at high densities” and the authors are:  Lewis Prole (Maynooth, Ireland), Paul Clark (Cardiff, UK), Felix Priestley (Cardiff, UK), Simon Glover (Heidelberg, Germany) and John Regan (Maynooth, Ireland). This paper, which presents a comparison of results obtained using chemical networks and a simpler equation-of-state approach for primordial star formation (showing the limitations of the latter) was published on 19th January 2024 and also in the folder marked Astrophysics of Galaxies.

Here is the overlay:

 

You can find the full text for this one on the arXiv here.

And that concludes the update. There’ll be more next week!

 

New Publication at the Open Journal of Astrophysics

Time to announce yet another new paper at the Open Journal of Astrophysics. This one was actually published on Friday (6th October 2023), but for one reason and another I’ve only just got around to announcing it here.

The latest paper is the 38th  so far in Volume 6 (2023) and the 103rd in all. The authors are: Matthew Price, Matthijs Mars, Matthew Docherty, Alessio Spurio Mancini, Augustin Marignier and Jason McEwen – all affiliated with University College London, UK.

The primary classification for this paper is Cosmology and Nongalactic Astrophysics and its title is “Fast emulation of anisotropies induced in the cosmic microwave background by cosmic strings”. It describes a  generative technique for producing generating cosmic microwave background temperature maps using wavelet phase harmonics. For an explanation of what a cosmic string is, see here. If you don’t know the difference between “emulation” and “simulation”, I refer you to the text!

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.

New Results from the Atacama Cosmology Telescope

I wish to draw your attention to a clutch of new papers out on the arXiv today (here, here and here) which describe latest results from the Atacama Cosmology Telescope (ACT for short). There was a webinar about this yesterday, which I failed to attend because I forgot about it.

The first of the papers listed above summarizes the key science results, which include a mass map obtained from gravitational lensing of the cosmic microwave background and its implications for cosmology.

As cosmic background photons propagate freely through space, i.e. without scattering, from the time of recombination to the observer, they are deflected by the gravitational effect of the large-scale distribution of matter in the Universe. This lensing effect leaves imprints in the temperature and polarization anisotropies, which can be used to reconstruct a map of the lensing potential, the gradient of which determines the lensing deflections. Structures in the CMB temperature pattern look bigger on the sky if we view them through an overdense clump of dark matter. By looking how the typical size of hot and cold spots in the CMB temperature map vary across the sky, it is possible to reconstruct the lensing deflections and hence the distribution of dark matter integrated along the line of sight. Since the structure through which the radiation passes is changing with time, this sort of map can provide constraints on models for the evolution of structure.

To cut a long story short, here is the map obtained using Data Release 6 of the ACT data over about 25% of the sky:

There’s a lot of information in the three papers but the key conclusion can be found in the last sentence of the abstract of the first paper:

Our results provide independent confirmation that the universe is spatially flat, conforms with general relativity, and is described remarkably well by the ΛCDM model, while paving a promising path for neutrino physics with gravitational lensing from upcoming ground-based CMB surveys.

Nothing revolutionary, then, but interesting nevertheless. There is an article on the BBC website about these results.

Two New Publications at the Open Journal of Astrophysics

I just realized that I forgot to advertise on here a couple of recent publications at the Open Journal of Astrophysics – the papers are coming in at quite a rate now – so I’ll catch up with them both in one post.

The first paper of the two is the 10th paper in Volume 6 (2023) and the 75th in all; it was published on 16th March 2023. This one is  in the folder marked Instrumentation and Methods for Astrophysics. The title is “From BeyondPlanck to Cosmoglobe: Open Science, Reproducibility, and Data Longevity” and it is a discussion of the importance of reproducibility and Open Science in CMB science including measures toward facilitating easy code and data distribution, community-based code documentation, user-friendly compilation procedures, etc.  You can find out more about the BeyondPlanck collaboration here and about Cosmoglobe here.

The first author is S. Gerakakis and there are 42 authors in all. This is too many to list individually here but they come from Greece, Norway, Finland, Germany, Italy, and the USA.

Here is a screen grab of the overlay 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.

The second paper is the 11th paper in Volume 6 (2023) as well as the 76th in all; this one was published last Thursday (23rd March). This is another for the folder marked Cosmology and Nongalactic Astrophysics. The title is “GLASS: Generator for Large Scale Structure” and the paper is about a new code for the simulation of cosmological observables obtainable from galaxy surveys in a realistic yet computationally inexpensive manner. The code can be downloaded here. This is an interesting approach that contrasts with the “brute force” of full numerical simulations like those I discussed a few days ago.

The authors are Nicolas Tessore (University College London), Arthur Loureiro (UCL, Edinburgh and Imperial College), Benjamin Joachimi (UCL), Maximilian von Wiestersheim-Kramsta (UCL) and Niall Jeffrey (UCL).

Here is a screen grab of the overlay 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.

Latest Results from the South Pole Telescope

Just time for a quick post to point out the latest results from the South Pole Telescope (SPT) have now hit the arXiv. The measurements were made in 2018 but the outcome of a full analysis of temperature and polarization has only just appeared.

Here’s a grab of the abstract:

The key figures showing the constraints on the Hubble Constant H₀ and the parameter S₈ are shown here:

As you can see, the results from SPT-3G are consistent with the standard cosmological model and agree on H₀ with Planck rather than the higher value obtained from local measurements. If you thought there was Hubble tension before this measurement, then you will still think so now!

Save the Holmdel Antenna!

I’ve used the above image hundreds of times in popular talks. It shows Robert W. Wilson (left) and Arno A. Penzias (right) standing in front of the famous horn antenna that (accidentally) discovered what we now know to be the cosmic microwave background radiation left over after the Big Bang. Penzias and Wilson made their historic measurements in 1964, published their results in 1965, and received the Nobel Prize for Physics in 1978.

At the time of their historic experiment, the scientists were working at Bell Telephone Laboratories at Holmdel, New Jersey, on Project Echo. The antenna was built to receive radio signals bounced off a passive satellite in a low Earth orbit to check the feasibility of satellite radio communication. They found excess noise in their receiver, which was eventually identified as a relic of a time when the Universe was extremely hot. Coincidentally, the theory of this yet undiscovered radiation was being worked on by Bob Dicke and his group in Princeton at about the same time (and also in New Jersey). Discussions ensued, and the discovery paper by Penzias & Wilson appeared in the Astrophysical Journal in 1965 beside a paper by Dicke et al. giving the theoretical interpretation.

Anyway, in case you were wondering whatever happened to the Holmdel Antenna, it is still there in Holmdel (at the top of Crawford Hill) and in 1988 was declared a National Historic Landmark:

Bell Labs (as it was usually known) was acquired by Nokia in 2016 and subsequently called Nokia Bell Labs. In 2019, however, Nokia put the entire Holmdel site up for sale and redevelopment of the entire site is currently being considered. This would not only bring to an end the connection between Holmdel and the telecommunications industry but also places a big question mark over the famous antenna. A petition has been raised to secure the future of this extremely important piece of scientific history. I encourage you to read more about the situation here and consider signing the petition.

Simons Observatory News

It seems a lot longer than four years ago that I drew the attention of readers of this blog to the science case for the Simons Observatory, the next big thing in ground-based studies of the cosmic microwave background.

The Simons Observatory Site in Chile, as it appeared four years ago

Obviously a couple of years of pandemic have intervened, amongst other things, but I was delighted to read yesterday that the UK has invested £18M in the Simons Observatory, which will enable further development of the facility at Cerro Toco, high above the Atacama Desert in Chile.

Simons Observatory in May 2022

The project was already a large international collaboration led from the USA, but the new funds from UKRI mean that six UK institutions will now join. These are (in alphabetical order): Cambridge; Cardiff; Imperial College London; Manchester; Oxford; and Sussex. Although I’m not involved in this project myself I know many people at these institutions (two of which I have worked at) and elsewhere who will be absolutely thrilled to be able to participate in this exciting project. Congratulations to them!

It would have been great if Ireland had been able to get involved in the Simons Observatory, but sadly fundamental science of this type is not a priority for the powers that be in Irish science funding. This is unfortunate because I think membership of international consortia like this would enable a small country to punch above its weight in science. Still, at least the UK PI, Prof. Michael Brown (Manchester), is an Irishman…

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