Users February 2024

users@lists.einsteintoolkit.org

15 participants
29 discussions

typo in GRHydro thorn guide?
by Bruno Giacomazzo 09 Feb '24

09 Feb '24

The GRHydro thorn guide ( https://einsteintoolkit.org/thornguide/EinsteinEvolve/GRHydro/documentation…) contains the following sentence: "However, in the vacuum limit the continuity equations describing the fluid break down. *The speed of sound tends to the speed of light* and everything fails (especially the conversion from conserved to primitive variables)." A student of mine wrote that the sound speed tends to the speed of light if rho tends to zero citing this, but is this correct? For example, taking a polytropic EOS P=k*rho^\gamma, the sound speed squared is (assuming c=1) cs^2= \gamma * k * rho^\gamma / (rho*h) with rho*h=rho+rho*eps+P=rho+\gamma*P/(\gamma-1) So cs^2 goes like rho^\gamma/(rho+\rho^gamma) and if \gamma>1 then cs^2->0 for rho->0 (while it goes to 1 if rho-> infinity). Am I missing something? Cheers, Bruno -- Prof. Bruno Giacomazzo Department of Physics University of Milano-Bicocca Piazza della Scienza 3 20126 Milano Italy email: bruno.giacomazzo(a)unimib.it phone: (+39) 02 6448 2321 web: http://www.brunogiacomazzo.org --------------------------------------------------------------------- There are only 10 types of people in the world: Those who understand binary, and those who don't ----------------------------------------------------------------------

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meeting minutes for 2024-02-08
by Steven Brandt 08 Feb '24

08 Feb '24

- Present: Roland, Steve, Peter, Leo, Sam, Zach - Release: - Still in feature proposal phase - Sam brought up release deadline on the CarpetX call: - LeanBSSN Molx - NewRadX - NPScalarsX - Summer Schools: - June 3-7 US ET Workshop - July 8-12 EU ET Workshop - Unanswered Questions: - Parameter file for BBH collision immersed in a scalar field. Helvi should respond. - Compiling on Frontera: Have to remove certain thorns to compile. We should be pushing the MakeThornList utility. - Compiling on Sciama: Bad compiler? - Our mailing list server seems unable to send out emails, Steve will fix. - We are running out of quota on Github, Roland will fix. - Open Tickets: - Tootle's request for more control of the link line, ordering of arguments. Maybe to use the ?_LIB_DIR to link and not use -L.

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Einstein Toolkit Meeting Reminder
by rhaas＠illinois.edu 07 Feb '24

07 Feb '24

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

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Agenda for Thursday's Meeting
by rhaas＠illinois.edu 05 Feb '24

05 Feb '24

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

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Spatial refinement factors
by Lorenzo Cipriani 05 Feb '24

05 Feb '24

Dear all, I have a brief question. I am trying to initialize a run with two very small stars (radius of ~300m) whose centers are at 750m from the origin; since I need a very fine grid, I am trying to use a refinement factor different from 2. In particular I am setting the Carpet::space_refinement_factors variable equal to [ [1,1,1], [5,5,5], ...] but I get the following error message: CarpetLib::dh::regrid(bool): Assertion `all(reffact == 2)' failed. This also happens if I change the Carpet::refinement_factor. Am I missing some obvious setting? Thank you very much for your help! Best, Lorenzo Cipriani

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Today: NR community call at 9am Pacific / noon NYC / 5pm London / 6pm Berlin
by Most, Elias R. 05 Feb '24

05 Feb '24

Dear Numerical Relativists, We’ll have our NR community call today, Monday Feb 5, 9am LA / noon NYC / 5pm London / 6pm Berlin in this Zoom room: https://caltech.zoom.us/j/87114806411 Our speakers today will be Xiaoyi Xie (AEI Potsdam / JET) and William Cook (FSU Jena / GR-Athena++). - Feel free to circulate this information within the NR community. - Please subscribe to our mailing list<https://groups.google.com/u/1/a/black-holes.org/g/nr-community-call/> to receive info on the community calls in the future (or send a short message to nr-community-call+subscribe(a)black-holes.org<mailto:nr-community-call+subscribe@black-holes.org> to subscribe) and join our Slack<https://join.slack.com/t/generalrelativity/shared_invite/zt-dl4gqb6v-aAuw~p…> for discussions (channel: #nr-community-call<https://generalrelativity.slack.com/archives/C021LLTLK37>). - Please sign up for a slot<https://docs.google.com/forms/d/e/1FAIpQLSfoCnnCJve7J7Jzrpdlqw7nAbwWS_iuX_e…> in the schedule to speak at one of the community calls: https://github.com/sxs-collaboration/nr-community-call/wiki Looking forward to seeing you all later, Nils

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Fw: [nr-community-call] Next NR community call: Monday, Feb 5
by Roland Haas 02 Feb '24

02 Feb '24

Begin forwarded message: Date: Fri, 2 Feb 2024 11:52:10 -0800 From: Nils Vu <nils.vu(a)black-holes.org> To: nr-community-call(a)black-holes.org Subject: [nr-community-call] Next NR community call: Monday, Feb 5 Dear Numerical Relativists, Our first NR community call of the year will be on Monday, Feb 5 (9am Pacific, noon NYC, 6pm Berlin). Our speakers will be Xiaoyi Xie (AEI Potsdam / JET) and William Cook (FSU Jena / GR-Athena++). You can find the schedule in the wiki: https://github.com/sxs-collaboration/nr-community-call/wiki As always: - Feel free to circulate this information within the NR community. - Please subscribe to our mailing list <https://groups.google.com/u/1/a/black-holes.org/g/nr-community-call/> to receive info on the community calls in the future (or send a short message to nr-community-call+subscribe(a)black-holes.org <mailto:nr-community-call+subscribe@black-holes.org> to subscribe) and join our Slack <https://join.slack.com/t/generalrelativity/shared_invite/zt-dl4gqb6v-aAuw*p…> for discussions (channel: #nr-community-call <https://generalrelativity.slack.com/archives/C021LLTLK37>). - Please sign up for a slot <https://docs.google.com/forms/d/e/1FAIpQLSfoCnnCJve7J7Jzrpdlqw7nAbwWS_iuX_e…> in the schedule to speak at one of the community calls: https://github.com/sxs-collaboration/nr-community-call/wiki Best, Nils — Nils Vu, Ph.D. (he/him) Sherman Fairchild Postdoctoral Fellow in Theoretical Astrophysics California Institute of Technology

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Parameter file for a binary BH merger immersed in a scalar field
by Samuel Gómez 01 Feb '24

01 Feb '24

Hi! My name is Samuel Gómez, physics student doing his master in Uppsala university, Sweden. Currently I am doing my master thesis with Joshua Eby from Stockholm University about the phenomenology of Gravitational Atoms around Neutron Stars and Black Holes. I would like to perform numerical simulations for a BH binary merger around a scalar cloud with EinsteinToolkit. From now, I have been able to simulate the example of the TOV star given in the EinteinToolkit official page in my laptop and soon I will gain access to a computer cluster where I hopefully will be able to install the Toolkit and perform a simulation for the example of a binary merger. But my aim is to be able to perform, maybe in its simplest version, a simulation of a merger around a scalar field, extracting information about both the evolution of the BHs and the scalar field itself. The problem I face is that I am not sure at all if I will be able to do it without any parameter file. As far as I understood, my current version of the Toolkit already has installed thorns related with the implementation of a scalar field (if I am not mistaken, one example is ScalarBase). I thus send this email asking if it is possible to obtain a parameter file for simulating this scenario, or to provide me with any information about an existing tutorial on how to write one. Something like this would help me a lot. I would appreciate any answer. Thanks!

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meeting minutes for 2024-02-01
by Roland Haas 01 Feb '24

01 Feb '24

Present: Roland, Peter, Steve, Zach, Bing-Ran HE, Leo, Sam, Shenfei, Yosef ET release: * discussed possible modules for inclusion, updated release timeline https://docs.einsteintoolkit.org/et-docs/Release_Details#Schedule ** GRHayL enabled IL-GRMHD ** tabulated EOS in GRHayLlib ** update Baikal to NRPy 2.0 ** possible FUKA updates * reviewers for ID thorns needed * Gallery runners: ** ask Deborah about BBH ** ask Peter for TOV ** Steve will try local students for a gallery example (Max Morris) ET US Meeting: * proposed time June 3 - 7 * organizing committee members (desired): ** Steve, Peter (local) ** Yosef (prior US meeting) ** Roland (general?), Zach (LIGO) ** Philipp (EU ET meeting) Cactus build system: * Steve brought up state of Cactus build system * possibility of moving over to cmake which is a more modern system compared to autoconf, of which we use an old, essentially unsupported version * would still require CST code for auto-generated code * possibility cmake and IDEs may be able to better understand where code comes from and what is auto-generated * some prior discussion: https://lists.einsteintoolkit.org/pipermail/users/2023-April/008911.html Unanswered questions: https://lists.einsteintoolkit.org/pipermail/users/2024-January/009196.html * discussed attempts by Robyn to make things build on Sciama * Steve took at look no specific solution suggestion 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 .

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