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Rotation curve fitting and its fatal attraction to cores in realistically simulated galaxy observations

Pineda, Juan C. B. and Hayward, Christopher C. and Springel, Volker and Mendes de Oliveira, Claudia (2017) Rotation curve fitting and its fatal attraction to cores in realistically simulated galaxy observations. Monthly Notices of the Royal Astronomical Society, 466 (1). pp. 63-87. ISSN 0035-8711. http://resolver.caltech.edu/CaltechAUTHORS:20170501-063311885

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Abstract

We study the role of systematic effects in observational studies of the cusp–core problem under the minimum disc approximation using a suite of high-resolution (25-pc softening length) hydrodynamical simulations of dwarf galaxies. We mimic realistic kinematic observations and fit the mock rotation curves with two analytic models commonly used to differentiate cores from cusps in the dark matter distribution. We find that the cored pseudo-isothermal sphere (ISO) model is strongly favoured by the reduced χ_ν^2 of the fits in spite of the fact that our simulations contain cuspy Navarro–Frenk–White profiles (NFW). We show that even idealized measurements of the gas circular motions can lead to the incorrect answer if velocity underestimates induced by pressure support, with a typical size of order ∼5 km s^(−1) in the central kiloparsec, are neglected. Increasing the spatial resolution of the mock observations leads to more misleading results because the inner region, where the effect of pressure support is most significant, is better sampled. Fits to observations with a spatial resolution of 100 pc (2 arcsec at 10 Mpc) favour the ISO model in 78–90 per cent of the cases, while at 800-pc resolution, 41–77 per cent of the galaxies indicate the fictitious presence of a dark matter core. The coefficients of our best-fitting models agree well with those reported in observational studies; therefore, we conclude that NFW haloes cannot be ruled out reliably from this type of analysis.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1093/mnras/stw3004DOIArticle
https://academic.oup.com/mnras/article/466/1/63/2566722/Rotation-curve-fitting-and-its-fatal-attraction-toPublisherArticle
ORCID:
AuthorORCID
Hayward, Christopher C.0000-0003-4073-3236
Springel, Volker0000-0001-5976-4599
Additional Information:© 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2016 November 17. Received 2016 October 21; in original form 2016 February 23. JCBP and CMdO would like to thank Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) for support fellowships 2012/21375-0, 2011/21678-0, and projects 2011/51680-6 and 2014/07684-5. CCH is grateful to the Gordon and Betty Moore Foundation for financial support. We thank Philippe Amram, Manoj Kaplinghat, Simon White, and Giuliano Lorio for useful discussions that helped us improve this manuscript. We also thank the referee, Kyle Oman, for carefully reading the manuscript and providing many useful comments that led us to improve the work. JCBP deeply acknowledges the hospitality of the Heidelberg Institute for Theoretical Studies (HITS), and Laboratoire d'Astrophysique de Marseille (LAM), where part of this work was done. The Flatiron Institute is supported by the Simons Foundation.
Group:TAPIR
Funders:
Funding AgencyGrant Number
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) 2012/21375-0
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) 2011/21678-0
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) 2011/51680-6
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) 2014/07684-5. CCH
Gordon and Betty Moore FoundationUNSPECIFIED
Simons FoundationUNSPECIFIED
Record Number:CaltechAUTHORS:20170501-063311885
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20170501-063311885
Official Citation:Juan C. B. Pineda, Christopher C. Hayward, Volker Springel, Claudia Mendes de Oliveira; Rotation curve fitting and its fatal attraction to cores in realistically simulated galaxy observations. Mon Not R Astron Soc 2017; 466 (1): 63-87. doi: 10.1093/mnras/stw3004
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:77076
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:01 May 2017 16:09
Last Modified:01 May 2017 16:09

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