Users November 2025

users@lists.einsteintoolkit.org

17 participants
22 discussions

Loss of convergence with subcycling in time
by Miguel Zilhão 17 Feb '26

17 Feb '26

hi all, we've recently added the option to compute the Gauss constraint in the ProcaEvolve thorn (https://bitbucket.org/canuda/proca/src/experimental_miguel/ProcaEvolve/) and we were surprised to see that, even for very small evolutions of a simple (unperturbed) charged black hole, this constraint violation does not converge. of course everything is converging just fine at t=0, but once the evolution starts, convergence is lost really quickly. after experimenting with different things, i think i've narrowed the issue down to the subcycling in time. i've attached some plots as well as the corresponding parameter files. these plots are not convergence tests, it's just what i'm observing with and without subcycling in time (everything else is the same as you can see from the parfiles). these are evolutions for a single charged BH, with Q=0.2. in one of the parfiles (LeanBSSN_RN_Q0.2_nosubcycl_hf40_202509.par) all timelevels update at the same rate with Carpet::time_refinement_factors = "[1, 1, 1, 1, 1, 1, 1]" for the other parfile (LeanBSSN_RN_Q0.2_hf40_202509.par), all timelevels update at the same rate *except* the two inner ones. for the "base" grid functions, i see no noticeable difference insofar as i've checked, but for the Gauss constraint violation the results are very different as you can see from the plots attached: - in the gc_x_RN_nosubcycl.pdf plot, everything looks fine - in the gc_x_RN_subcycl.pdf case, notice how a lot of noise propagates from the two inner refinements levels -- the ones that updated more frequently than the rest. the problem is that this noise is not contained in the buffer region (if it was, we'd be fine), but propagates out, contaminates the rest of the grid, and totally ruins any convergence study. actually a similar thing also happens for the hamiltonian constraint -- plots also attached (hc_x_RN_nosubcycl.pdf, hc_x_RN_subcycl.pdf) -- but in this case the effect is smaller and it doesn't spoil convergence studies. so i was wondering whether this is at all expected and/or if there are some parameters or setting that we may have overlooked? thanks, Miguel

4 7

Safe check of variable Coordinates::volume_form_state
by Jordan Nicoules 20 Jan '26

20 Jan '26

Dear all, I'm trying to extend our analysis thorn to tackle multipatch grids built with Llama. I want to use Coordinates::volume_form in the computation of volume integrals, by setting the corresponding parameter Coordinates::store_volume_form = yes. Our standard use case relies on Coordinates::coordinate_system = "Thornburg04", for which it works like a charm. However, except for this system and the analogous Thornburg13 (I have not tested it so far), it seems the variable Coordinates::volume_form_state is not modified nor initialized, whatever the value of the parameter Coordinates::store_volume_form. That makes the parameter insufficient by itself to perform checks. Moreover, since the flag is not initialized, we also can't simply check its value, which can be polluted. I have tried to use Carpet::poison_new_timelevels = yes and CarpetLib::poison_new_memory = yes, but it didn't seem to solve the issue. Hence, I would like to ask if there's another way to check for uninitialized values, a safe way to use the variables I mentioned in a general case, or any information/subtlety I may have missed? Ultimately, I can directly check Coordinates::coordinate_system, and output a warning/error if it's not of the types mentioned above. That feels a bit unsatisfactory, although I may default to it. Thank you very much for any help or insight you can provide! Best, Jordan Nicoules

2 6

Postdoctoral Position in Numerical Relativity and Fundamental Physics at the University of Illinois Urbana-Champaign
by Helvi Witek 26 Nov '25

26 Nov '25

Dear all, we are inviting applications for a postdoctoral position in numerical relativity and fundamental physics at the University of Illinois Urbana-Champaign. The successful candidate will work with Prof. Helvi Witek and her team, and they will have the opportunity to collaborate on the Einstein Toolkit/CarpetX software framework. Applicant should submit their application package (1) a cover letter, (2) a curriculum vitae, including a list of publications, (3) a research statement (limited to 3 pages, 1 inch margin, 11-12pt) containing a summary of previous and current research, and future research plans, (4) contact information for three (3) referees who will be asked to write letters of recommendation, by *December 1, 2025*, here:https://my.physics.illinois.edu/join/under “Postdoctoral Position in Numerical Relativity and Fundamental Physics with Dr. Helvi Witek – 2026.” The prospective start date of the position is August 2026. Please find the detailed announcement below. Best wishes Helvi --- The Illinois Relativity Group in the Department of Physics at the University of Illinois at Urbana-Champaign invites applications for a postdoctoral research position with focus on numerical relativity, computational astrophysics, and their applications to fundamental physics. The successful candidate will join Prof. Helvi Witek and her team to work on numerical relativity in and beyond general relativity, including tests of gravity or modeling signatures of dark matter candidates around black holes. The candidate is intended to partially work on the Einstein Toolkit/CarpetX software framework and contribute to its hybrid Monte-Carlo/M1 neutrino transport scheme as part of the “E=mc^2 ” project. This is a multi-institutional project to develop numerical infrastructure and methods, with collaborators at Louisiana State University, Rochester Institute of Technology, University of Idaho, University of Texas Austin, and the University of Wyoming, and international collaborators R. Haas and E. Schnetter. Prof. Helvi Witek’s team is currently home to postdoc Dr. Jay Kalinani, Visiting Research Scientist Dr. Elena Kopteva, six graduate students and undergraduate students; seehttps://witek-gravity-group.physics.illinois.edu. The successful candidate will become a member of the Illinois Relativity Group which includes Profs. S. Shapiro, H. O. Silva, N. Yunes, and Research Professor A. Tsokaros. They will also become part of a vibrant research community in the Illinois Center for Advanced Study of the University (ICASU;https://icasu.illinois.edu/) that bridges the Departments of Physics, Astronomy, Computer Science, Mathematics and the National Center for Supercomputing Applications (NCSA). ICASU faculty working in closely related areas include Profs. C. Gammie, G. Holder, J. Noronha-Hostler, J. Noronha, J. Shelton, and S. Vishveshwara. The successful candidate will also have opportunities to join the LISA Consortium (https://lisamission.org) and the Einstein Toolkit Consortium (https://einsteintoolkit.org). The candidate should have a strong background in scientific software development using parallelization frameworks like MPI or in numerical relativity in and beyond General Relativity. Expertise in GPU programming is beneficial. Interested candidates must have completed a Ph.D. in astronomy, physics, or a related field before the start date. They must submit their application package online here:https://my.physics.illinois.edu/join/under “Postdoctoral Position in Numerical Relativity and Fundamental Physics with Dr. Helvi Witek – 2026.” Applicants are requested to submit: (1) a cover letter, (2) a curriculum vitae, including a list of publications, (3) a research statement (limited to 3 pages, 1 inch margin, 11-12pt) containing a summary of previous and current research, and future research plans, (4) contact information for three (3) referees who will be asked to write letters of recommendation. The deadline for applications and all letters of recommendation is*December 1, 2025*, for full consideration. The anticipated starting date of the position is August 15, 2026, though other starting times may be negotiated. The position is expected to last for a two-year term with a potential extension to a third year, conditional on performance and/or funding availability. Please contact Prof. Helvi Witek (hwitek(a)illinois.edu) if you have any questions about the position itself, or Deanna Frye (ddebord(a)illinois.edu) if you have any questions about the application form. The University of Illinois System is an equal opportunity employer, including but not limited to disability and/or veteran status, and complies with all applicable state and federal employment mandates. Please visitRequired Employment Notices and Posters <https://www.hr.uillinois.edu/cms/one.aspx?portalId=4292&pageId=5705>to view our non-discrimination statement and find additional information about required background checks, sexual harassment/misconduct disclosures, and employment eligibility review throughE-Verify <https://www.e-verify.gov/sites/default/files/everify/posters/EVerifyPartici…>. Applicants with disabilities are encouraged to apply and may request a reasonable accommodation under the Americans with Disabilities Act (2008) to complete the application and/or interview process. --------------------------------------------- Dr. Helvi Witek Associate Professor Department of Physics University of Illinois at Urbana-Champaign 247 Loomis Lab 1110 W Green St Urbana, IL 61801 ---------------------------------------------

2 2

Agenda for Thursday's Meeting
by users＠einsteintoolkit.org 26 Nov '25

26 Nov '25

Please update the Wiki with agenda items for Thursday's meeting. Thanks! https://docs.einsteintoolkit.org/et-docs/meeting_agenda --The Maintainers

2 1

Fwd: postdoctoral Associate position in numerical relativity at Cornell
by Roland Haas 24 Nov '25

24 Nov '25

Hello all, to whom it may concern. Yours, Roland Begin forwarded message: Date: Mon, 24 Nov 2025 11:15:23 -0500 From: Nils Deppe <nd357(a)cornell.edu> To: Nils Deppe <nd357(a)cornell.edu> Subject: [sxs-announce] Postdoctoral Associate position in numerical relativity at Cornell The Cornell Center for Astrophysics and Planetary Science at Cornell University expects to have an opening for a Postdoctoral Associate in numerical relativity starting in September 2026. The position requires a Ph.D. and experience in numerical relativity or computational physics. The Cornell Relativity Group consists of Saul Teukolsky, Eanna Flanagan, Nils Deppe, Larry Kidder and research associates Mike Boyle and Will Throwe. There will also be opportunities to interact with the Theoretical Astrophysics Group, including Rachel Bean, David Chernoff, Dong Lai, and Ira Wasserman. Applicants should submit a cover letter, a CV (including list of publications) and a brief (1-3 pages) description of research interests and should arrange for three letters of reference to be submitted through Academic Jobs Online at https://academicjobsonline.org/ajo/jobs/31243 . All materials should be received by December 17, 2025. Best, Nils, Saul, and Larry Dr. Nils Deppe (he/him/his) Assistant Professor of Physics Department of Physics 446 Physical Sciences Building/604 Space Sciences Building Cornell University Ithaca, NY -- My email is as private as my paper mail. I therefore support encrypting and signing email messages. Get my PGP key from http://pgp.mit.edu .

1 0

Einstein Toolkit Meeting Reminder
by users＠einsteintoolkit.org 24 Nov '25

24 Nov '25

Hello, Please consider joining the weekly Einstein Toolkit phone call at 9:00 am US central time on Thursdays. For details on how to connect and what agenda items are to be discussed, use the link below. https://docs.einsteintoolkit.org/et-docs/Main_Page#Weekly_Users_Call --The Maintainers

2 1

Postdoctoral Associate position in numerical relativity at Cornell
by Nils Deppe 24 Nov '25

24 Nov '25

The Cornell Center for Astrophysics and Planetary Science at Cornell University expects to have an opening for a Postdoctoral Associate in numerical relativity starting in September 2026. The position requires a Ph.D. and experience in numerical relativity or computational physics. The Cornell Relativity Group consists of Saul Teukolsky, Eanna Flanagan, Nils Deppe, Larry Kidder and research associates Mike Boyle and Will Throwe. There will also be opportunities to interact with the Theoretical Astrophysics Group, including Rachel Bean, David Chernoff, Dong Lai, and Ira Wasserman. Applicants should submit a cover letter, a CV (including list of publications) and a brief (1-3 pages) description of research interests and should arrange for three letters of reference to be submitted through Academic Jobs Online at https://academicjobsonline.org/ajo/jobs/31243. All materials should be received by December 17, 2025. Best, Nils, Saul, and Larry Dr. Nils Deppe (he/him/his) Assistant Professor of Physics Department of Physics 446 Physical Sciences Building/604 Space Sciences Building Cornell University Ithaca, NY

1 0

Postdoctoral Position in Numerical Relativity at RIT
by Carlos O. Lousto 24 Nov '25

24 Nov '25

Postdoctoral Position in Numerical Relativity at the Rochester Institute of Technology (CCRG) ============================================================================================= The RIT’s Center for Computational Relativity and Gravitation (CCRG) is currently seeking to fill a postdoctoral research position. We are looking for highly qualified individuals interested in pursuing research in the fields of numerical relativity, simulations of compact object mergers, such as stellar or supermassive black hole binaries, strongly emitting gravitational waves. The group is actively developing new numerical codes and tools as part of The Einstein Toolkit Consortium. The CCRG hosts a number of research scientists and students involved in gravitational wave data analysis from the LIGO Scientific Collaboration and the LISA consortium. Our researchers have access to several computing cluster facilities at national computing centers such as the TACC’s supercomputers, ACCESS, and dedicated over 3500-cores clusters with 5 PB of storage pool hosted at the Center. Applications should consist of a cover letter, a brief statement of research interests, a curriculum vitae including publication list, and at least three letters of recommendation. All materials should be sent electronically as soon as possible to: ccrg-postdoc[AT]ccrg.rit.edu<http://ccrg.rit.edu/>. More information about the CCRG is available at http://ccrg.rit.edu/ , and about Rochester at http://en.wikipedia.org/wiki/Rochester,_New_York Application reviews will be begin immediately and continue until this highly competitive position is filled. Final deadline for submission is January 31st 2026. Starting dates, duration and a competitive salary are negotiable. ----- Distinguished Prof. Carlos O. Lousto https://ccrg.rit.edu/user/carlos.lousto

1 0

Re: [Users] Problem with tutorial
by Roland Haas 20 Nov '25

20 Nov '25

Hello Julia, Very good. Thanks for letting me know. Yours, Roland > [CAUTION: Non-UBC Email] > > Dear Roland, > Thank you very much for your help. Yes, the tutorial is working for me now. > Best wishes, > Julia > ________________________________ > Von: Roland Haas <rhaas(a)mail.ubc.ca> > Gesendet: Donnerstag, 20. November 2025 00:14 > An: Julia Speicher via Users <users(a)einsteintoolkit.org> > Cc: Julia Speicher <j.i.speicher(a)uva.nl> > Betreff: Re: [Users] Problem with tutorial > > Hello Julia, > > Sorry for the delay, but this turned into a bit more of a rabbit hole > than expected. > > Please give this another try on the tutorial server. You will have to, > unfortunately, start from scratch to get new versions of the simfactory > machine description files. > > If you like to you can also try and update only Simulation Factory > using: > > cd repos/simfactory2 > git pull > > then remove your configs/sim directory to force a compilation from > scratch using the new files. > > On you laptop things probably work fine, at least as long as there is > no pro-compiled version of ADIOS2 installed already. On a cluster with > ADIOS2 installed you may need to use branch rhaas/mpilibs of > ExternalLibraries/ADIOS2 which we hope to very soon merge into > ExternalLibraries/ADIOS2's master branch. > > Please let me know if this solves the issue for you. > > Just in case (though I suspect you are aware) there is the group of > Philipp Moesta at UVA that uses the EinsteinToolkit extensively and may > be able to provide some help as well. > > Yours, > Roland > > > Hello Julia, > > > > > I am new to the Einstein toolkit, so I wanted to go through the tutorial first. Unfortunately, I do not get beyond the step of building the Einstein toolkit: > > > %%bash > > > ./simfactory/bin/sim build -j2 --thornlist thornlists/einsteintoolkit.th > > > > > > I attached the output as a text file due to its length. The output ends with: > > > /usr/bin/ld: /usr/local/lib/../lib/libadios2_cxx11_mpi.so.2.10: error adding symbols: DSO missing from command line > > > collect2: error: ld returned 1 exit status > > > make[1]: *** [/home/j/Cactus/lib/make/make.configuration:150: /home/j/Cactus/exe/cactus_sim] Error 1 > > > make: *** [Makefile:265: sim] Error 2 > > Hmm, that is a linker error. My guess would be that one needs to > > explicitly list the C++ bindings for MPI in the linker library list. > > > > This should of course work automatically, but clearly is not anymore. > > > > > I am running the web-based tutorial, so I thought just running the > > > Jupyter notebook cells would suffice (I tried restarting the kernel, > > > but this did not help). > > > > In particular on the ET maintained tutorial server it should just work. > > Since it is not, we will have to fix the server and the code. > > > > > Do you know how I could resolve this error? > > > > Let me try and see and get back to you. > > > > Yours, > > Roland > > > > -- > My email is as private as my paper mail. I therefore support encrypting > and signing email messages. Get my PGP key from http://pgp.mit.edu/<http://pgp.mit.edu/> . -- My email is as private as my paper mail. I therefore support encrypting and signing email messages. Get my PGP key from http://pgp.mit.edu .

1 0

Meeting Minutes for 2025-11-13
by Leo Rosa Werneck 20 Nov '25

20 Nov '25

Hi all, Here are the minutes for last week’s meeting. Cheers, Leo ------ Present: Lucas (Chair), Leo (Minutes), Peter, Steve, Keith, Beyhan, Deborah, Johnny, Roland, Yuvraj Sharma, Zach ** Agenda Items ** * EU ET School & Workshop - https://sites.google.com/view/eetk25/programme - Abstract deadline is tomorrow (14 Nov 2025), so please submit your abstracts, if you haven't yet. ** Unanswered Question on Mailing List ** None. ** Open Tickets & Tickets for Review ** * #2899: Appears to be a CarpetLib issue in the parfile. * #2898: Add caching to CarpetX interpolator. Lucas implemented a solution, but Roland and others requested that the cache be made visible, so users can understand resource use. * #2897: Suggestion made, waiting for OP to respond. * #2896: Adds `push_url` support to GetComponents. * #2892: Apparent an issue with AMReX and Tursa, which was resolved by running the code elsewhere. The issue appears to be reproducible. * #2886: Fortran support in progress. ------ Leonardo R. Werneck, Ph.D. Postdoctoral researcher Office EP 314 | Department of Physics | University of Idaho 875 Perimeter Dr. MS 0903 Moscow, ID 83844-0903, USA leonardo(a)uidaho.edu <mailto:leonardo@uidaho.edu> https://leowerneck.github.io <https://leowerneck.github.io/>

1 0

2026

2025

2024

2023

2022

2021

2020

2019

2018

2017

2016

2015

2014

2013

2012

2011

2010

Users November 2025