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Weekly Update from the Open Journal of Astrophysics – 10/05/2025

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , on May 10, 2025 by telescoper

It’s time for another update Saturday morning update of activity at the Open Journal of Astrophysics. After the record-breaking stats described in the last update , this week has been on the slow side with just one paper published. This brings the number in Volume 8 (2025) up to 55 and the total so far published by OJAp up to 290.

The paper to report is “Late-time growth weakly affects the significance of high-redshift massive galaxies” by Qianran Xia & Dragan Huterer (U. Michigan, USA) and Nhat-Minh Nguyen (U. Tokyo, Japan). This paper, which was published on Wednesday 7th May 2025,  is published in the folder Cosmology and NonGalactic Astrophysics. It presents an argument that changes in the growth rate of perturbations at low redshift do not have much effect on predictions of the abundance of lassive galaxies at high redshift.

The overlay is here:

 

You can find the officially accepted version on arXiv here.

That’s all for now. I’ll do another update next week.

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Weekly Update from the Open Journal of Astrophysics – 03/05/2025

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , , , , , , , on May 3, 2025 by telescoper

Saturday morning once again, and time for another update of papers published at the Open Journal of Astrophysics. It’s been a recording-breaking week: since the last update we have published no fewer than ten papers, which brings the number in Volume 8 (2025) up to 54 and the total so far published by OJAp up to 289.

The first paper to report is “Subspace Approximations to the Focused Transport Equation of Energetic Particles, I. The Standard Form” by B. Kippenstein & A. Shalchi (U. Manitoba, Canada). This paper, which was published on Monday 28th April 2025, presents a hybrid analytical-numerical method to solve the Fokker-Planck equation for the transport of energetic particles. It is published in the folder Solar and Stellar Astrophysics.

The overlay is here:

You can find the officially accepted version on arXiv here.

Next is “The Importance of Subtleties in the Scaling of the ‘Terminal Momentum’ For Galaxy Formation Simulations” by Philip F. Hopkins (Caltech, USA). This presents a technical discussion of issues surrounding the proper modelling of supernova blast waves and their effects in numerical simulations of galaxy formation. It was published on Tuesday 29th April 2025 in the folder Astrophysics of Galaxies. The overlay is here:

The final version can be found on arXic here.

Next one up is “Local variations of the radial metallicity gradient in a simulated NIHAO-UHD Milky Way analogue and their implications for (extra-)galactic studies” by Sven Buder (ANU, Australia), Tobias Buck (U. Heidelberg, Germany), Qian-Hui Chen (ANU) and Kathryn Grasha (ANU). This one was also published on Tuesday 29th April 2025 in the folder Astrophysics of Galaxies. It describes a numerical study of the variation of chemical abundance with radial position in galaxies and the implications of this for galaxy formation. Here is the overlay:

and you can find the final accepted version on arXiv here.

The fourth paper this week is “Zooming In On The Multi-Phase Structure of Magnetically-Dominated Quasar Disks: Radiation From Torus to ISCO Across Accretion Rates” by Philip F. Hopkins (Caltech, USA) and 14 others based in the USA and Canada. This was also published on Tuesday 29th April 2025 in the folder Astrophysics of Galaxies. It presents very detailed numerical study of the structure of magnetized quasar accretion disks. The overlay is here:

You can find the official final version on arXiv here.

Next is “Tomographic halo model of the unWISE-Blue galaxies using cross-correlations with BOSS CMASS galaxies” by Alex Krolewski, Jensen Lawrence, and Will J. Percival (U. Waterloo, Canada). This one was also published on 29th April 2025, which was a busy day(!), but in the folder Cosmology and NonGalactic Astrophysics.  This paper describes using the halo model to create mock samples unWISE-Blue galaxies, applicable to other tomographic cross-correlations between photometric samples and narrowly-binned spectroscopic samples. The overlay is here:

The final version of this one can be found on the arXiv here.

Number six for this week is “StratLearn-z: Improved photo-estimation from spectroscopic data subject to selection effects” by Chiara Moretti (SISSA, Trieste, Italy), Maximilian Autenrieth (Imperial College, UK), Riccardo Serra (SISSA), Roberto Trotta (SISSA), David A. van Dyk (Imperial) and Andrei Mesinger (SNS Pisa, Italy). This was published on Thursday 1st May 2025 in the folder Cosmology and NonGalactic Astrophysics. This one is about estimating photometric redshifts using an approach that relies on splitting the source and target datasets into strata based on estimated propensity score. The overlay is here:

 

The official version can be found on arXiv here.

Next is “The Impact of Galaxy-halo Size Relations on Galaxy Clustering Signals” by Joshua B. Hill and Yao-Yuan Mao (U. Utah, USA). This one was also published on May 2nd 2025 and is in the folder Astrophysics of Galaxies. It discusses the challenge of identifying a specific galaxy halo property that controls galaxy sizes through constraints from galaxy clustering alone. The overlay is here:

You can find the official version of the paper on arXiv here.

The next paper is “Detection of Thermal Emission at Millimeter Wavelengths from Low-Earth Orbit Satellites” by Allen Foster (Princeton, USA) and an international cast of 90 others, which is too many to list individually. This one was also published on Thursday May 1st but is in the folder Instrumentation and Methods for Astrophysics.  The paper discusses the experimental detection of thermal emission from satellites and a discussion of the implications for astrophysical observations, especially time-domain astronomy. The overlay is here:

You can find the final version of the paper on arXiv here.

The penultimate paper of this week is “Pseudo-Cls for spin-s fields with component-wise weighting” by David Alonso (U. Oxford, UK). This one was published yesterday (Friday 2nd May 2025).  The paper presents an approach to power spectrum estimation appropriate for data with anisotropic noise properties or for which complicated masks are required.  It can be found in the folder Cosmology and NonGalactic Astrophysics. The overlay is here:

 

The final version of this paper is on arXiv here.

The last paper this week is “The past, present and future of observations of externally irradiated disks” by Planet formation environments collaboration: Megan Allen (U. Sheffield, UK) and 52 others. This paper was published on Friday 2nd May in the folder Solar and Stellar Astrophysics.  It presents a review of research on the effects of the ultraviolet radiation environment on protoplanetary disc evolution and planet formation. The overlay is here:

You can find the final version on arXiv here.

That’s all the papers for this week. I’ll just add that there were quite a few gremlins at Crossref this week, particularly yesterday. I usually do the publishing first thing in the morning but yesterday’s papers were held in a queue for most of the day pending registration. Usually it just takes a few minutes, but for these I had to wait several hours but we got there in the end. Although ten papers is more than we have ever published in a week, we still haven’t had a week in which we’ve published on every working day!

Anyway, that’s all for this week. I’ll post another update next Saturday.

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Euclid on Sky

Posted in Euclid, The Universe and Stuff with tags , , , on May 2, 2025 by telescoper

I haven’t posted much recently about the European Space Agency’s Euclid Mission but I’ve got an excuse to remedy that today as I’ve just seen that the Special Issue of Astronomy & Astrophysics called Euclid on Sky has at last been published (with a date of 30th April 2025). This contains the main mission and instrument overview papers as well as scientific papers relating to the Early Release Observations. All the individual papers have been on arXiv for some time already.

You can access the Special Issue here.

The main mission overview paper has 1139 authors (including yours truly); that’s definitely the longest author list I’ve ever been on! The arXiv version has been available for almost a year and has already got 254 citations. Here is the abstract:

The current standard model of cosmology successfully describes a variety of measurements, but the nature of its main ingredients, dark matter and dark energy, remains unknown. Euclid is a medium-class mission in the Cosmic Vision 2015-2025 programme of the European Space Agency (ESA) that will provide high-resolution optical imaging, as well as near-infrared imaging and spectroscopy, over about 14,000 deg^2 of extragalactic sky. In addition to accurate weak lensing and clustering measurements that probe structure formation over half of the age of the Universe, its primary probes for cosmology, these exquisite data will enable a wide range of science. This paper provides a high-level overview of the mission, summarising the survey characteristics, the various data-processing steps, and data products. We also highlight the main science objectives and expected performance.

Here’s Figure 1.

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Weekly Update from the Open Journal of Astrophysics – 26/04/2025

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , on April 26, 2025 by telescoper

It’s Satuday morning once again, and time for another update of papers published at the Open Journal of Astrophysics. Since the last update we have published two papers, which brings the number in Volume 8 (2025) up to 44 and the total so far published by OJAp up to 279.

The first paper to report is “Approximating non-Gaussian Bayesian partitions with normalising flows: statistics, inference and application to cosmology” by Tobias Röspel, Adrian Schlosser & Björn Malte Schäfer (Universität Heidelberg, Germany) which was published on April 23rd 2025 in the folder Cosmology and NonGalactic Astrophysics. It is an introduction to normalizing flows – a machine learning technique for transforming distributions – and its application to the extraction of cosmological parameters from supernova data.

The overlay is here:

You can find the officially accepted version on arXiv here.

The other paper this week is “Dwarf Galaxies in the TNG50 Field: connecting their Star-formation Rates with their Environments” by Joy Bhattacharyya & Annika H.G. Peter (Ohio State University, USA) and Alexie Leauthaud (UC Santa Cruz, USA).  This one was published on 24th April 2025 in the older Astrophysics of Galaxies and it studies dwarf galaxies with properties similar to the Large and Small Magellanic Clouds that form in different environments in the TNG50 simulation of the IllustrisTNG project.

The overlay is here:

 

and you can find the final accepted version on arXiv here.

 

That’s all for this week. I’ll have another update next Saturday.

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Crisis at NASA

Posted in Euclid, Politics, The Universe and Stuff with tags , , , on April 23, 2025 by telescoper

The scientific community has been waiting for several weeks to find out precisely how heavily the Trump/Musk axe would fall on the National Aeronautics and Space Administration (NASA); this article reveals the shocking scale of the proposed cuts.

Under the proposal, NASA’s Science Mission Directorate (SMD) would receive almost a 50% reduction in its Budget. Within the individual SMD Divisions:

  • Planetary Science would have its budget cut from the current level of $2,717 Million to $1,929 Million;
  • Earth Science would see a cut from the current budget level of $2,195 Million to $1,033 Million;
  • Astrophysics would decrease from its current level of $1,530 Million to $487 Million;
  • Heliophysics budget would decrease from its current level of $805 M to $455 M.

It’s very bad news all round for NASA science, but the worst hit is Astrophysics (which includes cosmology) where the proposed cut is about two-thirds, which would be truly devastating. According to the American Astronomical Society,

The proposed cut to the astrophysics budget is likely to result in the cancellation of the Nancy Grace Roman Space Telescope, a Great Observatory that would revolutionize our understanding of dark matter and dark energy while also detecting hundreds of thousands of planets in other solar systems. As the Roman Space Telescope is already fully assembled and on budget for a launch in two years, a cancellation of the mission would be a significant waste of taxpayer dollars. 

The Nancy Grace Roman Space Telescope (formerly known as WFIRST) is in many ways complementary to Euclid, though it will survey a smaller area of sky it has an telescope twice the diameter of Euclid so will reach fainter magnitudes. It has been threatened before, in Trump’s previous administration, but it survived. It is not clear that it will do so again as the current composition of Congress is not weighted favourably.

Those of us outside the United States can do little, but in case anyone reading this is in America the AAS has an Action Alert for you to contact your representative(s) to vote against the proposal.

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Weekly Update from the Open Journal of Astrophysics – 19/04/2025

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , , , , , , , on April 19, 2025 by telescoper

It may be the Easter holiday weekend, but it’s still time for the weekly Saturday morning update of papers published at the Open Journal of Astrophysics. Since the last update we have published five new papers, which brings the number in Volume 8 (2025) up to 42 and the total so far published by OJAp up to 277.

In chronological order of publication, the five 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.

The first paper to report is “Galaxy Clustering with LSST: Effects of Number Count Bias from Blending” by Benjamin Levine (Stony Brook, NY), Javier Sánchez (STScI, MD), Chihway Chang (Chicago, IL) Anja von der Linden (Stony Brook), Eboni Collins (Dillard, LA), Eric Gawiser (Rutgers, NJ), Katarzyna Krzyżańska (Cornell, NY), Boris Leistedt (Imperial College, UK) on behalf of the LSST Dark Energy Science Collaboration.

This presents a simulation-based study of the effect of source overlaps (blending) on galaxy counts expected for the Vera C. Rubin Legacy Survey of Space and Time (LSST). The paper is in the folder Cosmology and NonGalactic Astrophysics and was published on Monday 14th April 2025. The overlay is here:

 

You can find the officially-accepted version of the paper on arXiv here.

The second paper to announce, published onTuesday 15th April 2025,  “Rapid, strongly magnetized accretion in the zero-net-vertical-flux shearing box” by Jonathan Squire (Otago, New Zealand), Eliot Quataert (Princeton, USA) & Philip F. Hopkins (Caltech, USA). This  paper presents a numerical study of turbulence in a flux shearing box, with discussion of the implications of the results for global accretion disk models and simulations thereof. It was published in the folder High-Energy Astrophysical Phenomena and the overlay is here:

 

You can read the officially accepted version of this paper on arXiv here.

The third paper of the week, published on Wednesday April 16th 2025,   is “DeepDISC-photoz: Deep Learning-Based Photometric Redshift Estimation for Rubin LSST” by Grant Merz (University of Illinois at Urbana-Champaign, USA) and 13 others (all based in the USA) on behalf of the LSST Dark Energy Science Collaboration. This paper describes adding photometric redshift estimation to the DeepDISC framework for classification objects in co-added images for use with the Vera C. Rubin LSST survey. It can be found in the folder Instrumentation and Methods for Astrophysics.

Here is the overlay:

 

You can find the officially accepted version of this paper on arXiv here.

The next one to report is “Multidimensional Nova Simulations with an Extended Buffer and Lower Initial Mixing Temperatures” by Alexander Smith Clark and Michael Zingale (Stony Brook University, NY, USA). This paper presents new computer models of classical novae with improved ability to follow nucleosynthesis in the thermonuclear outburst and better treatment of convective transport. This one was also published on Wednesday 16th April 2025 but in the folder Solar and Stellar Astrophysics.

Here is the overlay:

 

The official published version can be found on the arXiv here.

The last paper of the five published this week is “Measurement of the power spectrum turnover scale from the cross-correlation between CMB lensing and Quaia” by David Alonso (Oxford, UK), Oleksandr Hetmantsev (Kyiv, Ukraine), Giulio Fabbian (Cambridge, UK), Anze Slosar (Brookhaven National Laboratory, USA) and Kate Storey-Fisher (Stanford, USA). This is a discussion of using the spatial correlations of quasars and their cross-correlations with cosmic microwave background lensing data to measure a feature corresponding to the matter-radiation equality scale with consequences for cosmological parameter estimation. It was published on Thursday 17th April 2025 in the folder Cosmology and NonGalactic Astrophysics.

The overlay is here:

You can find the officially accepted version on arXiv here.

That’s all the papers for this week. I’ll just add a couple of things.

One is that, although there have been weeks before in which we have published five or more papers, we still haven’t managed to have a week on which we’ve published a paper on every weekday. This week we had two on Wednesday 16th but didn’t have any yesterday (Friday).

The second is that tt has been a while since I last posted a breakdown of the running costs here at the Open Journal of Astrophysics. Today I received an email from Scholastica, our service provider, reminding me our costs will go up shortly (from 22nd April). In the interest of transparency I am passing this information on here.

The new prices will be as follows:

  • Peer Review System annual cost will be $425/year (was $350/year) plus $10 per submission (no change)
  • OA Publishing Platform annual cost will be $1,499/year (was $1,399/year)

Last year we published 120 papers with about 250 submissions. We’re a bit ahead of that this year, so I estimate that our next year’s costs will be a bit less than $5000. That’s still less than the typical APC for a single paper at many journals.

I hope this clarifies the situation.

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Biosignature Hype

Posted in Astrohype, Bad Statistics, The Universe and Stuff with tags , , , , on April 17, 2025 by telescoper

I was thinking just the other day that I haven’t posted much in either the Astrohype or the Bad Statistics folders on this blog. Well today I found an item that belongs in both categories. Many people will have seen the widespread press coverage of a misleading claim of the discovery of alien life; see, e.g., here. This misleading press coverage is based on a misleading press release from the University of Cambridge which you can find here.

The story is based on a paper in the pay-to-publish Astrophysical Journal Letters with the title “New Constraints on DMS and DMDS in the Atmosphere of K2-18 b from JWST MIRI“. The DMS and DMDS in the title refer to Dimethyl Sulphide and Dimethyl Disulphide respectively. These are interpreted by the authors as biosignatures.

There are two main problems with this claim. One is that DMS and DMDS are not necessarily biosignatures in the first place; see here for the reasons. The other is that there isn’t even any evidence for the detection of DMS or DMDS anyway. Here is the spectrum of which the lead author of the paper, Prof. Nikku Madhusudhan, has claimed “the signal came through loud and clear”.

Yeah, right. In statistical terms this is a non-detection. The Bayes Factor used in the paper to quantify the evidence for a model with DMS and/or DMDS over one without is just 2.62 in the logarithm. That’s not a detection by any stretch of the imagination; to be anywhere near convincing a Bayes Factor has to be at least 100. The subsequent cherry-picking of the data to improve the apparent probability of a detection is just statistical flummery.

Notice that the use of the phrase “Constraints on” in the title of the paper does not indicate that the article presents evidence that a detection has been made. That the claim has somehow morphed into the “the strongest evidence for life beyond our solar system” is absurd. The most charitable thing I can say is that Prof. Madhusudhan must have been carried away by enthusiasm. This doesn’t reflect very well on Cambridge University either.

This episode worries me greatly. This is a time of increasing hostility towards science and this sort of thing can only make matters worse. Scientists need to be much more careful in communicating the uncertainties in their results.

UPDATE: There’s a now paper on arXiv here that argues that a straight line is a better fit to the data, in other words that there is no strong statistical evidence for spectral features at all.

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That was the Dean’s Lecture that was..

Posted in Biographical, Maynooth, The Universe and Stuff with tags , , on April 15, 2025 by telescoper
Left to Right: John Regan, Neil Trappe, Brian Schmidt and myself

As it was foretold, last night we had a very special event in Maynooth in the form of a public lecture with the title The Universe from Beginning to End by Nobel Laureate Prof. Brian Schmidt. Brian actually arrived on Sunday and is still here today; he will be returning to Australia from Dublin this evening. It was really great of him to take the time to visit us here in Maynooth not just for the lecture but to chat informally with staff and students. He also did some interviews with the media, e.g. here and here.

The talk, which was for a lay audience, was extremely well attended. In fact we had to move it to a larger venue than we originally intended. I don’t know the official attendance figures but I would guess somewhere between 400 and 500 people came. The talk was excellent, and there were lots of very good questions from the audience afterwards which Brian dealt with very engagingly. The talk was recorded and if it becomes available publicly I will provide a link.

At the end I even found myself on the list to have dinner with Brian in a local restaurant. All in all, it was an excellent day.

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Weekly Update from the Open Journal of Astrophysics – 12/04/2025

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , , , , on April 12, 2025 by telescoper

Time for the weekly Saturday morning update of papers published at the Open Journal of Astrophysics. Since the last update we have published four new papers, which brings the number in Volume 8 (2025) up to 37 and the total so far published by OJAp up to 272.

In chronological order of publication, 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.

The first paper to report is “Searching for new physics using high precision absorption spectroscopy; continuum placement uncertainties and the fine structure constant in strong gravity” by Chung-Chi Lee (Big Questions Institute (BQI), Sydney, Australia), John K. Webb (Cambridge, UK), Darren Dougan (BQI), Vladimir A. Dzuba & Victor V. Flambaum (UNSW, Australia) and Dinko Milaković (Trieste, Italy).

This presents a discussion of the problem of continuum placement in high-resolution spectroscopy, which impacts significantly on fine structure constant measurements, and a method for mitigating its effects. The paper is in the folder Solar and Stellar Astrophysics and was published on Tuesday 8th April 2025. The overlay is here:

You can find the officially-accepted version of the paper on arXiv here.

The second paper to announce, also published on 8th April 2025,  is “Deciphering Spatially Resolved Lyman-Alpha Profiles in Reionization Analogs: The Sunburst Arc at Cosmic Noon” by Erik Solhaug (Chicago, USA), Hsiao-Wen Chen (Chicago), Mandy C. Chen (Chicago),  Fakhri Zahedy (University of North Texas),  Max Gronke (MPA Garching, Germany),  Magdalena J. Hamel-Bravo (Swinburne, Australia), Matthew B. Bayliss (U. Cincinatti), Michael D. Gladders  (Chicago), Sebastián López (Universidad de Chile), Nicolás Tejos (Universidad Católica de Valparaíso, Chile).

This paper, which presents a study of the Lyman-alpha emission properties of a gravitationally-lensed galaxy at redshift z=2.37, appears in the folder Astrophysics of Galaxies. It was published

 

 

 

You can read the officially accepted version of this paper on arXiv here.

The third paper of the week  is “On the progenitor of the type Ia supernova remnant 0509-67.5” by Noam Soker (Technion, Haifa, Israel). This one was published on Wednesday 9th April 2025 in the folder High-Energy Astrophysical Phenomena. The author discusses possible ideas for the origin of a supernova that exploded inside a planetary nebula.

Here is the overlay:

 

You can find the officially accepted version of this paper on arXiv here.

Last (but certainly) not least for this week, published on April 11th 2025, we have “Are Models of Strong Gravitational Lensing by Clusters Converging or Diverging?” by Derek Perera (U. Minnesota), John H Miller Jr & Liliya L. R. Williams (U. Minnesota, USA), Jori Liesenborgs (Hasselt U., Belgium), Allison Keen (U. Minnesota), Sung Kei Li (Hong Kong University), Marceau Limousin (Aix Marseille Univ., France).  This papers study various models of a strong gravitational lensing system, the results suggesting that lens models are neither converging to nor diverging from a common solution for this system, regardless of method.

Here is the overlay:

 

 

The official published version can be found on the arXiv here.

 

That’s all the papers for this week. By way of a postscript I’ll just mention that the gremlins that have affected submissions to Crossref (which we rely on for registering the article metadata) have now been resolved and normal services have been restored.

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R.I.P. Jerry Ostriker (1937-2025)

Posted in R.I.P., The Universe and Stuff with tags , , , , , , on April 9, 2025 by telescoper

Once again I find myself using this blog to pass on sad news. This time it is of the death of renowned astrophysicist Jerry Ostriker (pictured left in 2012), who passed away on Monday 6th April 2025 just a week before his 88th birthday.

Jeremiah Paul Ostriker (to give his full name) was an extremely energetic, versatile and influential theorist who worked on a wide range of problems in diverse areas of astrophysics and produced a number of classic papers. Close to my own specialism I would quote two in particular: one written with Jim Peebles in 1973 about the stability of galactic disks; and the other with Martin Rees in 1977 about the role of gas cooling and fragmentation in determining the size of galaxies and clusters. He also did much to establish the use of hydrodynamic simulations in cosmology and was an early adopter of the current standard cosmological model, including a cosmological constant. He worked on many other things too, including pulsars and galactic nuclei.

I only met Jerry Ostriker a few times, mainly at conferences – where he was never shy to contribute to discussions after talks – but also once back in the 1990s when I was a visitor Princeton (where he was Professor). I didn’t have much time to talk to him then as he always seemed to be on the go, so I never really got to know him personally. After spending most of his career in Princeton, including a spell as Provost, in 2001 Ostriker moved to Cambridge for a short stint as Plumian Professor, before returning to Princeton.

There is a very nice obituary of Jerry Ostriker by Dennis Overbye in the New York Times.

Rest in peace, Jerry Ostriker

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