Constraining the dipolar magnetic field of M82 X-2 by the accretion model

Abstract

Recently, ultraluminous X-ray source (ULX) M82 X-2 has been identified to be an accreting neutron star, which has a $P=1.37$ s spin period, and is spinning up at a rate $\dot{P}=-2.0\times 10^{-10}\mathrm{s}{\mathrm{s}}^{-1}$. Interestingly, its isotropic X-ray luminosity $L_{\mathrm{iso}}=1.8\times 10^{40}\mathrm{erg}{\mathrm{s}}^{-1}$ during outbursts is 100 times the Eddington limit for a $1.4{\mathrm{M}}_{\odot }$ neutron star. In this Letter, based on the standard accretion model we attempt to constrain the dipolar magnetic field of the pulsar in ULX M82 X-2. Our calculations indicate that the accretion rate at the magnetospheric radius must be super-Eddington during outbursts. To support such a super-Eddington accretion, a relatively high multipole field ($\ga 10^{13}$ G) near the surface of the accretor is invoked to produce an accreting gas column. However, our constraint shows that the surface dipolar magnetic field of the pulsar should be in the range of $1.0-3.5\times 10^{12}$ G. Therefore, our model supports that the neutron star in ULX M82 X-2 could be a low magnetic field magnetar (proposed by Tong) with a normal dipolar field ($\sim 10^{12}$ G) and relatively strong multipole field. For the large luminosity variations of this source, our scenario can also present a self-consistency interpretation.

arXiv comment4 pages, 1 figure, MNRAS Letters in press

References in corpus (32)

• An Ultraluminous X-ray Source Powered by An Accreting Neutron Star
• Ultraluminous X-Ray Sources in External Galaxies
• The Nature of Accreting Black Holes in Nearby Galaxy Nuclei
• Super-Eddington Fluxes from Thin Accretion Disks?
• Ultraluminous X-ray Sources in the Chandra and XMM-Newton Era
• A low-magnetic-field Soft Gamma Repeater
• A mass of less than 15 solar masses for the black hole in an ultraluminous X-ray source
• On the maximum accretion luminosity of magnetized neutron stars: connecting X-ray pulsars and ultraluminous X-ray sources
• Population X: Are the super-Eddington X-ray sources beamed jets in microblazars or intermediate mass black holes?
• A new low magnetic field magnetar: the 2011 outburst of Swift J1822.3-1606
• Puzzling accretion onto a black hole in the ultraluminous X-ray source M101 ULX-1
• Propeller effect in action in the ultraluminous accreting magnetar M82 X-2
• Evidence for "Propeller" Effects In X-ray Pulsars GX 1+4 And GROJ1744-28
• ULXs: Neutron Stars vs Black Holes
• The ultra luminous X-ray source NuSTAR J095551+6940.8: A magnetar in a high mass X-ray binary
• A 62 Day X-Ray Periodicity and an X-Ray Flare from the Ultraluminous X-Ray Source in M82
• Spectral State Transitions in Aql X-1: Evidence for `Propeller' Effects
• 3XMM J185246.6+003317: another low magnetic field magnetar
• NuSTAR J095551+6940.8: a highly magnetised neutron star with super-Eddington mass accretion
• Is SGR 0418+5729 indeed a waning magnetar ?
• An ultraluminous nascent millisecond pulsar
• Spectral and temporal properties of the ultra-luminous X-ray pulsar in M82 from 15 years of Chandra observations and analysis of the pulsed emission using NuSTAR
• Discovery of mHz X-ray Oscillations in a Transient Ultraluminous X-ray Source in M82
• Discovery of the transient magnetar 3XMM J185246.6+003317 near supernova remnant Kesteven 79 with XMM-Newton
• A Population of Ultraluminous X-ray Sources with An Accreting Neutron Star
• The Ultraluminous X-ray Sources near the Center of M82
• An accreting low magnetic field magnetar for the ultraluminous X-ray source in M82
• The accretion regimes of a highly magnetised NS: the unique case of NuSTAR J095551+6940.8
• The Magnetic Field Evolution of ULX NuSTAR J095551+6940.8 in M82--A Legacy of Accreting Magnetar
• Evolution of Intermediate-Mass Black Hole X-Ray Binaries
• Accretion mode of the Ultra-Luminous X-ray source M82 X-2
• The X-ray Pulsar M82 X-2 on its Propeller Line

Cited by in corpus (11)

• Hot disk of the Swift J0243.6+6124 revealed by Insight-HXMT
• Swift observations of SMC X-3 during its 2016-2017 super-Eddington outburst
• A Population of Neutron Star Ultraluminous X-ray Sources with A Helium Star Companion
• Accreting magnetars: linking ultraluminous X-ray pulsars and the slow pulsation X-ray pulsars
• The origin of the bimodal luminosity distribution of ultraluminous X-ray pulsars
• On the magnetic field of the ultraluminous X-ray pulsar M82 X-2
• High Energy Gamma Rays from Nebulae Associated with Extragalactic Microquasars and Ultra-Luminous X-ray Sources
• The Great Pretenders Among the ULX Class
• Are there magnetars in high-mass X-ray binaries?
• Study on the magnetic field of the ultraluminous X-ray pulsar RX J0209.6-7427
• Exploring the magnetic field of the ultraluminous X-ray pulsar NGC 4631 X-8