The First Day in the Life of a Magnetar: Evolution of the Inclination Angle, Magnetic Dipole Moment and Braking Index of Millisecond Magnetars During Gamma-Ray Burst Afterglows
arXiv:1904.06769 · doi:10.3847/1538-4357/ab498c
Abstract
The afterglow emission of some gamma-ray bursts (GRBs) show a shallow decay (plateau) phase implying continuous injection of energy. The source of this energy is very commonly attributed to the spin-down power of a nascent millisecond magnetar. The magnetic dipole radiation torque is considered to be the mechanism causing the spin-down of the neutron star. This torque has a component working for the alignment of the angle between rotation and magnetic axis, i.e., inclination angle, which has been neglected in modelling GRB afterglow light curves. Here, we demonstrate the evolution of the inclination angle and magnetic dipole moment of nascent magnetars associated with GRBs. We constrain the initial inclination angle, magnetic dipole moment and rotation period of seven magnetars by modelling the seven long-GRB afterglow light curves. We find that, in its first day, the inclination angle of a magnetar decreases rapidly. The rapid alignment of the magnetic and rotation axis may address the lack of persistent radio emission from mature magnetars. We also find that in three cases the magnetic dipole moments of magnetars decrease exponentially to a value a few times smaller than the initial value. The braking index of nascent magnetars, as a result of the alignment and magnetic dipole moment decline, is variable during the afterglow phase and always greater than three.
arXiv comment13 pages, 8 figures, 4 tables, accepted for publication in ApJ
References in corpus (36)
- emcee: The MCMC Hammer
- GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
- The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
- Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
- Multi-messenger Observations of a Binary Neutron Star Merger
- Methods and results of an automatic analysis of a complete sample of Swift-XRT observations of GRBs
- Beaming in Gamma-Ray Bursts: Evidence for a Standard Energy Reservoir
- Physical processes shaping GRB X-ray afterglow lightcurves: theoretical implications from the Swift XRT observations
- An online repository of Swift/XRT light curves of GRBs
- Evidence for a Canonical GRB Afterglow Light Curve in the Swift/XRT Data
- Time-dependent force-free pulsar magnetospheres: axisymmetric and oblique rotators
- Transient pulsed radio emission from a magnetar
- Data analysis recipes: Using Markov Chain Monte Carlo
- The prompt energy release of gamma-ray bursts using a cosmological k-correction
- Fallback accretion in the aftermath of a compact binary merger
- The X-ray afterglow flat segment in short GRB 051221A: Energy injection from a millisecond magnetar?
- Time evolution of pulsar obliquity angle from 3D simulations of magnetospheres
- Period clustering of the Anomalous X-ray Pulsars and magnetic field decay in magnetars
- Evolution of the Magnetic Field Structure of the Crab Pulsar
- The Central X-Ray Point Source in Cassiopeia A
- Constraining the Braking Indices of Magnetars
- Polarized radio emission from a magnetar
- The braking index of millisecond magnetars
- Constraints on millisecond magnetars as the engines of prompt emission in gamma-ray bursts
- Chandra pulsar survey (ChaPS)
- Neutron-star spindown and magnetic inclination-angle evolution
- A correlation between intrinsic brightness and average decay rate of Swift UVOT GRB optical/UV light curves
- The 30-Year Search for the Compact Object in SN 1987A
- Search for radio pulsations in four Anomalous X-ray Pulsars and discovery of two new pulsars
- Evolution of non-spherical pulsars with plasma-filled magnetospheres
- The 2018 X-ray and Radio Outburst of Magnetar XTE J1810-197
- Exploding neutron stars in close binaries
- Magnetars in Ultra-Long Gamma-Ray Bursts
- Constraining the Braking Index and Energy Partition of Magnetar spindown with {\em Swift}/XRT data
- On the new braking index of PSR B0540-69: further support for magnetic field growth of neutron stars following submergence by fallback accretion
- Coherent radio emission from a twisted magnetosphere after magnetar-quake
Cited by in corpus (15)
- The evolution of binary neutron star post-merger remnants: a review
- Redback: A Bayesian inference software package for electromagnetic transients
- Gravitational waves or deconfined quarks: what causes the premature collapse of neutron stars born in short gamma-ray bursts?
- Magnetar birth: rotation rates and gravitational-wave emission
- Evidence for magnetar precession in X-ray afterglows of gamma-ray bursts
- Towards Nebular Spectral Modeling of Magnetar-Powered Supernovae
- Gravitational waves from mountains in newly born millisecond magnetars
- Interpreting the X-ray afterglows of gamma-ray bursts with radiative losses and millisecond magnetars
- Timescales for detection of super-Chandrasekhar white dwarfs by gravitational wave astronomy
- Early Evolution of a Newborn Magnetar with Strong Precession Motion in GRB 180620A
- Comparison of the Characteristics of Magnetars Born in Death of Massive Stars and Merger of Compact Objects With {\em Swift} Gamma-Ray Burst Data
- Detection possibility of continuous gravitational waves from rotating magnetized neutron stars
- The initial evolution of millisecond magnetars: an analytical solution
- GRB 111209A/SN 2011kl: Collapse of a supramassive magnetar with r-mode oscillation and fall-back accretion onto a newborn black hole
- X-ray Flares Raising upon Magnetar Plateau as an Implication of a Surrounding Disk of Newborn Magnetized Neutron Star