UvA-DARE (Digital Academic Repository) The Wind Nebula around Magnetar Swift J1834.9-0846 Younes, G.; Kouveliotou, C.; Kargaltsev, O.; Gill, R.; Granot, J.; Watts, A.L.; Gelfand, J.; Baring, M.G.; Harding, A.; Pavlov, G.G.; van der Horst, A.J.; Huppenkothen, D.; Göğüş, E.; Lin, L.; Roberts, O.J. DOI 10.3847/0004-637X/824/2/138 Publication date 2016 Document Version Final published version Published in Astrophysical Journal Link to publication Citation for published version (APA): Younes, G., Kouveliotou, C., Kargaltsev, O., Gill, R., Granot, J., Watts, A. L., Gelfand, J., Baring, M. G., Harding, A., Pavlov, G. G., van der Horst, A. J., Huppenkothen, D., Göğüş, E., Lin, L., & Roberts, O. J. (2016). The Wind Nebula around Magnetar Swift J1834.9-0846. Astrophysical Journal, 824(2), [138]. https://doi.org/10.3847/0004-637X/824/2/138 General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. UvA-DARE is a service provided by the library of the University of Amsterdam (https://dare.uva.nl) Download date:25 Sep 2021 The Astrophysical Journal, 824:138 (12pp), 2016 June 20 doi:10.3847/0004-637X/824/2/138 © 2016. The American Astronomical Society. All rights reserved. THE WIND NEBULA AROUND MAGNETAR SWIFT J1834.9–0846 G. Younes1, C. Kouveliotou1, O. Kargaltsev1, R. Gill2, J. Granot2, A. L. Watts3, J. Gelfand4, M. G. Baring5, A. Harding6, G. G. Pavlov7, A. J. van der Horst1, D. Huppenkothen8,9,E.GöğüŞ10, L. Lin11, and O. J. Roberts12 1 Department of Physics, The George Washington University, Washington, DC 20052, USA 2 Department of Natural Sciences, The Open University of Israel, 1 University Road, P.O. Box 808, Raánana 43537, Israel 3 Astronomical Institute “Anton Pannekoek,” University of Amsterdam, Postbus 94249, 1090 GE Amsterdam, The Netherlands 4 NYU Abu Dhabi, P.O. Box 903, New York, NY 10276, USA 5 Department of Physics and Astronomy, Rice University, MS-108, P.O. Box 1892, Houston, TX 77251, USA 6 Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA 7 Department of Astronomy & Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802, USA 8 Center for Data Science, New York University, 726 Broadway, 7th Floor, New York, NY 10003, USA 9 Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003, USA 10 Sabancı University, Orhanlı-Tuzla, İstanbul 34956, Turkey 11 Department of Astronomy, Beijing Normal University, Beijing, 100875, China 12 School of Physics, University College Dublin, Stillorgan Road, Belfield, Dublin 4, Ireland Received 2016 February 24; revised 2016 April 13; accepted 2016 April 18; published 2016 June 21 ABSTRACT We report on the analysis of two deep XMM-Newton observations of the magnetar Swift J1834.9−0846 and its surrounding extended emission taken in 2014 March and October, 2.5 and 3.1 yr after the source went into outburst. The magnetar is only weakly detected in the first observation, with an absorption-corrected flux -14 −1 −2 −14 F0.5- 10 keV »´410erg s cm and a 3s upper limit during the second observation of about 3 × 10 erg s−1 cm−2. This flux level is more than 3 orders of magnitude lower than the flux measured at the outburst onset in 2011 September. The extended emission, centered at the magnetar position and elongated toward the southwest, is clearly seen in both observations; it is best fit by a highly absorbed power law (PL), with a hydrogen column 22 −2 density of NH =´8.0 10 cm and PL photon index G =2.2 0.2. Its flux is constant between the two -12 −1 −2 observations at F0.5- 10 keV =´1.3 10 erg s cm .Wefind no statistically significant changes in the spectral shape or the flux of this extended emission over a period of 9 yr from 2005 to 2014. These new results strongly support the extended emission nature as a wind nebula and firmly establish Swift J1834.9−0846 as the first magnetar to show a surrounding wind nebula. Further, our results imply that such nebulae are no longer exclusive to rotation-powered pulsars and narrow the gap between these two subpopulations of isolated neutron stars. The size and spectrum of the nebula are compatible with those of pulsar-wind nebulae, but its radiative fi ˙ ef ciency hX =»LEX 0.1 is markedly high, possibly pointing to an additional wind component in Swift J1834.9−0846. Key words: stars: individual (Swift J1834.9–0846) – stars: magnetars – stars: neutron – X-rays: ISM 1. INTRODUCTION Finally, a few magnetars have also shown pulsed radio emission (Camilo et al. 2006, 2007; Rea et al. 2012; Torne Magnetars represent a subclass of isolated neutron stars et al. 2015). (NSs) with a unique set of observational properties. They often In the past decade, several observational results have have long spin periods (P ~ 21– 2 s) and large spin-down rates demonstrated that the above properties are neither exclusively (P˙ ~ 10--13– 10 10). They are usually observed as bright X-ray 32 36 −1 seen in magnetars nor solely attributed to superstrong surface sources with luminosities LX ~ 10– 10 erg s , larger than dipole fields (B Bcrit). For the purposes of this study, we their corresponding rotational energy losses single out below two of these results. ( ˙ 2˙ 3 30 35 −1 -EIPProt =~()21010p – erg s , where I is the NS PSR J1846−0258 is a 0.3 s rotation-powered pulsar (RPP) ≈ 45 2) moment of inertia, I 10 gcm . Almost all have been located inside the supernova remnant (SNR) Kes 75. Its spin- (∼ ) ( 37 40 ) observed to emit short 0.1 s , bright Eburst ~ 10– 10 erg , down rate implies a surface dipole magnetic field hard X-ray bursts (see Mereghetti et al. 2015; Turolla B =´4.9 1013 G, on the boundary between RPPs and et al. 2015, for reviews). Assuming dipole braking, the classical magnetars (Gotthelf et al. 2000). Unlike magnetars, majority of magnetar timing properties indicate strong surface however, PSR J1846−0258 has a large rotational energy loss 13 36 −1 dipole magnetic fields (B Bcrit, where Bcrit =´4.4 10 Gis rate, E˙ =´8.1 10 erg s , well above its persistent X-ray fi ) 34 −1 the electron quantum critical eld , while their internal luminosity, LX =´4.1 10 erg s . Its rotational energy loss magnetic fields are thought to be even larger (Thompson & also powers a bright pulsar wind nebula (PWN), 35 −1 Duncan 1995). The decay of their internal and external LX,PWN =´1.4 10 erg s , with an X-ray efficiency fi ˙ magnetic elds represents their dominant energy reservoir, hPWN ==LEX 2%, somewhat high but not unusual for a powering their persistent emission, as well as their bursting young RPP (Ng et al. 2008). The source spin-down age is activity (Thompson & Duncan 1995, 1996; Thompson t =-=Pn()188 P˙ 4 yr for a measured breaking index of et al. 2002; Beloborodov 2009; Dall’Osso et al. 2012). n = 2.65 (Livingstone et al. 2006). Gavriil et al. (2008) 1 The Astrophysical Journal, 824:138 (12pp), 2016 June 20 Younes et al. reported the discovery of short hard X-ray bursts from PSR Table 1 J1846−0258, a trademark of typical magnetar sources. The Log of the XMM-Newton Observations fl bursts were accompanied by ux enhancement and timing Observation ID Date Instrument Good Time Intervals noise, also typical properties of magnetars. These observational (ks) results demonstrated that an otherwise typical RPP can in fact 0723270101 2014 Mar 16 PN 70.0 show typical magnetar properties, bridging the gap between the 2014 Mar 16 MOS1 87.7 two NS subpopulations. 2014 Mar 16 MOS2 88.5 The discovery in 2009 of SGR J0418+5729 strengthened 0743020201 2014 Oct 16 PN 60.0 the above conclusion. The source was detected after it emitted 2014 Oct 16 MOS1 78.0 two short hard X-ray bursts (van der Horst et al. 2010), and 2014 Oct 16 MOS2 77.7 exhibited typical magnetar-like properties: a period of ∼9s,X- ray flux enhancement soon after the bursts, and a quasi- exponential flux decay in the following months (Esposito (Tian et al. 2007). They suggested that a previous outburst from et al. 2010; Rea et al. 2013). A spin-down rate could only be the source prior to 2005 might be responsible for its earlier measured after 3 yr of observations, and it was found to be the detection. The asymmetrical shape was attributed to nonuni- lowest of any magnetar, P˙ =´410-15 ss−1, implying a formity in the dust distribution. surface dipole field B =´61012 G (Rea et al. 2010). This In this paper, we report on the analysis of two deep XMM- field is well within the range of regular RPPs, indicating that a Newton observations of Swift J1834.9−0846 and its associated strong dipole field is not a requirement for displaying extended emission taken in 2014 March and in 2014 October, magnetar-like properties in an isolated NS.