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Magnetic effects on the low-T/|W| instability in differentially rotating neutron stars

Muhlberger, Curran D. and Nouri, Fatemeh Hossein and Duez, Matthew D. and Foucart, Francois and Kidder, Lawrence E. and Ott, Christian D. and Scheel, Mark A. and Szilágyi, Béla and Teukolsky, Saul A. (2014) Magnetic effects on the low-T/|W| instability in differentially rotating neutron stars. Physical Review D, 90 (10). Art. No. 104014. ISSN 0556-2821. http://resolver.caltech.edu/CaltechAUTHORS:20150107-084235303

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Abstract

Dynamical instabilities in protoneutron stars may produce gravitational waves whose observation could shed light on the physics of core-collapse supernovae. When born with sufficient differential rotation, these stars are susceptible to a shear instability (the “low-T/|W| instability”), but such rotation can also amplify magnetic fields to strengths where they have a considerable impact on the dynamics of the stellar matter. Using a new magnetohydrodynamics module for the Spectral Einstein Code, we have simulated a differentially-rotating neutron star in full 3D to study the effects of magnetic fields on this instability. Though strong toroidal fields were predicted to suppress the low-T/|W| instability, we find that they do so only in a small range of field strengths. Below 4×10^(13) G, poloidal seed fields do not wind up fast enough to have an effect before the instability saturates, while above 5×10^(14) G, magnetic instabilities can actually amplify a global quadrupole mode (this threshold may be even lower in reality, as small-scale magnetic instabilities remain difficult to resolve numerically). Thus, the prospects for observing gravitational waves from such systems are not in fact diminished over most of the magnetic parameter space. Additionally, we report that the detailed development of the low-T/|W| instability, including its growth rate, depends strongly on the particular numerical methods used. The high-order methods we employ suggest that growth might be considerably slower than found in some previous simulations.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1103/PhysRevD.90.104014 DOIArticle
http://journals.aps.org/prd/abstract/10.1103/PhysRevD.90.104014PublisherArticle
http://arxiv.org/abs/1405.2144arXivArticle
Additional Information:© 2014 American Physical Society. Received 12 May 2014; published 17 November 2014. We extend our thanks to D. Lai for inspiring this investigation, to M. Boyle for advice on several occasions, and to F. Hébert for catching errors in the text. We also extend our gratitude to S. Bernuzzi, R. De Pietri, B. Giacomazzo, and L. Rezzolla, whose correspondence after the first version of this paper helped to clarify the comparison between their simulations and ours. The authors at Cornell gratefully acknowledge support from National Science Foundation (NSF) Grants No. PHY- 1306125 and No. AST-1333129, while the authors at Caltech acknowledge support from NSF Grants No. PHY-1440083 and No. AST-1333520 and NSF CAREER Award No. PHY-1151197. Authors at both Caltech and Cornell also thank the Sherman Fairchild Foundation for their support. F. Foucart gratefully acknowledges support from the Vincent and Beatrice Tremaine Postdoctoral Fellowship, from the NSERC of Canada, from the Canada Research Chairs Program, and from the Canadian Institute for Theoretical Astrophysics. Finally, the authors at WSU acknowledge support through NASA Grant No. NNX11AC37G and NSF Grant No. PHY-1402916. Some computations were performed on the GPC supercomputer at the SciNet HPC Consortium [53], funded by the Canada Foundation for Innovation under the auspices of Compute Canada, the Government of Ontario, Ontario Research Fund–Research Excellence, and the University of Toronto. This work also used the Extreme Science and Engineering Discovery Environment (XSEDE) through allocations No. TG-PHY100033 and No. PHY990002, supported by NSF Grant No. OCI-1053575. Additionally, this research was performed in part using the Zwicky computer system operated by the Caltech Center for Advanced Computing Research and funded by NSF MRI No. PHY-0960291 and the Sherman Fairchild Foundation.
Group:TAPIR
Funders:
Funding AgencyGrant Number
NSFPHY-1306125
NSFAST-1333129
NSFPHY-1440083
NSFAST-1333520
NSFPHY-1151197
Sherman Fairchild FoundationUNSPECIFIED
Vincent and Beatrice Tremaine Postdoctoral FellowshipUNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Canada Research Chairs ProgramUNSPECIFIED
Canadian Institute for Theoretical AstrophysicsUNSPECIFIED
NASA NNX11AC37G
NSFPHY-1402916
NSFTG-PHY100033
NSFTG-PHY990002
NSFOCI-1053575
NSFPHY-0960291
Classification Code:PACS: 04.25.D-, 04.40.Dg, 04.30.Db
Record Number:CaltechAUTHORS:20150107-084235303
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20150107-084235303
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:53255
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:07 Jan 2015 17:02
Last Modified:20 Feb 2015 17:53

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