Investigations of the Ohmic Decay and the Soft X-Ray Emission of the High-braking-index Pulsar PSR J1640-4631

doi:10.1088/1538-3873/ab0440

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	Investigations of the Ohmic Decay and the Soft X-Ray Emission of the High-braking-index Pulsar PSR J1640-4631
	Wang, Hui4,5 ; Gao, Zhifu3 ; Wang, Na3 ; Jia, Huanyu 5; Li, Xiangdong 2,6; Zhi, Qijun 1,4
刊名	PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC
	2019-05-01
卷号	131 期号:999 页码:054201
关键词	Individual PSR J1640-4631 Ohmic decay Thermoplastic wave heating
ISSN号	0004-6280
DOI	10.1088/1538-3873/ab0440
产权排序	3
英文摘要	The young pulsar PSR J1640-4631 is the first pulsar reported with a high braking index, n = 3.15 +/- 0.03, and has attracted extensive attention. In this work, by inputting the equation of state, we obtain two typical and feasible ranges of the electrical conductivity in the crust of PSR J1640-4631. Then, by considering the effects of general relativity, we formulate the induction equation and use it to investigate the decay of crustal magnetic fields within two scenarios: pure Ohmic decay, and the combination of Ohmic decay and Hall drift. In the former scenario, we calculate the current magnetic field decay rates as dB(p)/dt similar to (0.78-1.00) x 10(7) G yr(-1) and dB(t)/dt similar to (0.82-1.05) x 10(8) G yr(-1) for the poloidal and toroidal parts, respectively, and estimate the current magnetic energy decay rate as L-B similar to (0.95-1.22) x 10(32) erg s(-1). In the latter scenario, the combination of Ohmic decay and Hall drift accelerates the decay of magnetic fields, and we calculate the current magnetic field decay rates as dB(p)/dt similar to (1.26-1.47) x 10(7) G yr(-1), and dB(t)/dt similar to (1.32-1.54) x 10(8) G yr(-1) for the poloidal and toroidal parts, respectively, and estimate the current magnetic energy decay rate as L-B similar to (1.86-2.18) x 10(32) erg s(-1). It is found that the recalculated value of the braking index n of the star is lower than its observed value, which implies that other factors influence the spin-down evolution. The current magnetic energy decay rates calculated in both scenarios are far less than the isotropic soft X-ray luminosity obtained from Chandra+NuStar telescopes. The observed soft X-ray flux in the (2-10) keV band is F-X similar to 1.8(4) x 10(-13) erg cm(-2) s(-1), which corresponds to a high surface temperature, T similar to 1.54(6) x 10(6) K. The observed X-ray flux of the star could be caused by the decay of a multipolar magnetic field near the pole, which is strong enough to activate the slot-gap mechanism. The high surface temperature of the star is attributed either to magnetic spot formation or thermoplastic wave heating due to the decay of the toroidal field near the pole. Our results could be useful in interpreting the high soft X-ray flux from high magnetic field pulsars.
资助项目	National Basic Research Program of China grants 973 Programs[2015CB857100] ; Chinese National Science Foundation[11175417] ; Chinese National Science Foundation[11173042] ; Chinese National Science Foundation[11547311] ; Chinese National Science Foundation[11847307] ; Chinese National Science Foundation[11333004] ; Chinese National Science Foundation[11773015] ; Chinese National Science Foundation[11573016] ; Chinese National Science Foundation[11565010] ; Chinese National Science Foundation[U18311120] ; Chinese National Science Foundation[U1731218] ; Chinese National Science Foundation[U1838201] ; Science and Technology Fund of Guizhou Province[(2015)5015] ; Science and Technology Fund of Guizhou Province[(2016)4008] ; Guizhou Provincial Joint Fount[(2017)7349] ; Doctor Starting Up Foundation of Guizhou Normal University[0516134] ; National Key Research and Development Program of China[2016YFA0400803]
WOS关键词	MAGNETIC-FIELD EVOLUTION ; NEUTRON-STAR CRUSTS ; SURFACE-TEMPERATURE ; DENSE MATTER ; GAMMA-RAY ; SPIN-DOWN ; CORE ; INSTABILITY ; DIVERSITY ; EQUATION
WOS研究方向	Astronomy & Astrophysics
语种	英语
出版者	IOP PUBLISHING LTD
WOS记录号	WOS:000461954200001
内容类型	期刊论文
源URL	[http://ir.xao.ac.cn/handle/45760611-7/2536]
专题	研究单元未命名
通讯作者	Gao, Zhifu
作者单位	1.Guizhou Normal Univ, Sch Phys & Elect Sci, Guiyang 550001, Guizhou, Peoples R China 2.Nanjing Univ, Dept Astron, Nanjing 210046, Jiangsu, Peoples R China 3.Chinese Acad Sci, Xinjiang Astron Observ, 150,Sci 1 St, Urumqi 830011, Xinjiang, Peoples R China 4.Guizhou Normal Univ, Guizhou Prov Key Lab Radio Astron & Data Proc, Guiyang 550001, Guizhou, Peoples R China 5.Southwest Jiaotong Univ, Sch Phys Sci & Technol, Chengdu 610031, Sichuan, Peoples R China 6.Nanjing Univ, Key Lab Modern Astron & Astrophys, Nanjing 210046, Jiangsu, Peoples R China
推荐引用方式 GB/T 7714	Wang, Hui,Gao, Zhifu,Wang, Na,et al. Investigations of the Ohmic Decay and the Soft X-Ray Emission of the High-braking-index Pulsar PSR J1640-4631[J]. PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC,2019,131(999):054201.
APA	Wang, Hui,Gao, Zhifu,Wang, Na,Jia, Huanyu,Li, Xiangdong,&Zhi, Qijun.(2019).Investigations of the Ohmic Decay and the Soft X-Ray Emission of the High-braking-index Pulsar PSR J1640-4631.PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC,131(999),054201.
MLA	Wang, Hui,et al."Investigations of the Ohmic Decay and the Soft X-Ray Emission of the High-braking-index Pulsar PSR J1640-4631".PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC 131.999(2019):054201.