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Evidence for a Variable Ultrafast Outflow in the Newly Discovered Ultraluminous Pulsar NGC 300 ULX-1

Kosec, P. and Pinto, C. and Walton, D. J. and Fabian, A. C. and Bachetti, M. and Fürst, F. and Grefenstette, B. W. (2018) Evidence for a Variable Ultrafast Outflow in the Newly Discovered Ultraluminous Pulsar NGC 300 ULX-1. Monthly Notices of the Royal Astronomical Society, 479 (3). pp. 3978-3986. ISSN 0035-8711. doi:10.1093/mnras/sty1626.

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Ultraluminous pulsars are a definite proof that persistent super-Eddington accretion occurs in nature. They support the scenario according to which most Ultraluminous X-ray Sources (ULXs) are super-Eddington accretors of stellar mass rather than sub-Eddington intermediate mass black holes. An important prediction of theories of supercritical accretion is the existence of powerful outflows of moderately ionized gas at mildly relativistic speeds. In practice, the spectral resolution of X-ray gratings such as RGS onboard XMM–Newton is required to resolve their observational signatures in ULXs. Using RGS, outflows have been discovered in the spectra of three ULXs (none of which are currently known to be pulsars). Most recently, the fourth ultraluminous pulsar was discovered in NGC 300. Here we report detection of an ultrafast outflow (UFO) in the X-ray spectrum of the object, with a significance of more than 3σ, during one of the two simultaneous observations of the source by XMM–Newton and NuSTAR in December 2016. The outflow has a projected velocity of 65 000 km s^(−1)(0.22c) and a high ionization factor with a log value of 3.9. This is the first direct evidence for a UFO in a neutron star ULX and also the first time that this evidence in a ULX spectrum is seen in both soft and hard X-ray data simultaneously. We find no evidence of the UFO during the other observation of the object, which could be explained by either clumpy nature of the absorber or a slight change in our viewing angle of the accretion flow.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Pinto, C.0000-0003-2532-7379
Walton, D. J.0000-0001-5819-3552
Fabian, A. C.0000-0002-9378-4072
Bachetti, M.0000-0002-4576-9337
Fürst, F.0000-0003-0388-0560
Grefenstette, B. W.0000-0002-1984-2932
Additional Information:© 2018 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2018 June 12. Received 2018 June 12; in original form 2018 March 5. Published: 20 June 2018. We are grateful to the anonymous referee for useful comments that improved the clarity and quality of the paper. PK acknowledges support from the Science and Technology Facilities Council (STFC). CP and ACF acknowledge support from the European Research Council Advanced Grant Feedback 340442. DJW acknowledges support from STFC Ernest Rutherford fellowships. This work is based on observations obtained with XMM–Newton, an ESA science mission funded by ESA Member States and USA (NASA). This research has used the NASA/IPAC Extragalactic Database (NED) that is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This research has used the SIMBAD database, operated at CDS, Strasbourg, France.
Group:Space Radiation Laboratory, NuSTAR
Funding AgencyGrant Number
Science and Technologies Facilities Council (STFC)UNSPECIFIED
European Research Council (ERC)340442
European Space Agency (ESA)UNSPECIFIED
Issue or Number:3
Record Number:CaltechAUTHORS:20180308-083847600
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Official Citation:P Kosec, C Pinto, D J Walton, A C Fabian, M Bachetti, M Brightman, F Fürst, B W Grefenstette; Evidence for a variable Ultrafast Outflow in the newly discovered Ultraluminous Pulsar NGC 300 ULX-1, Monthly Notices of the Royal Astronomical Society, Volume 479, Issue 3, 21 September 2018, Pages 3978–3986,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:85195
Deposited By: Joy Painter
Deposited On:08 Mar 2018 16:48
Last Modified:15 Nov 2021 20:26

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