The evolution effects of radius and moment of inertia for rapidly rotating neutron stars

Abstract

A newly born millisecond magnetar is thought to be the central engine of some gamma-ray bursts (GRBs), especially those that present long-lasting X-ray plateau emissions. By solving the field equations, we find that when the rotational speed of the magnetar is approaching the breakup limit, its radius $R$ and moment of inertia $I$ would undergo an obvious evolution as the magnetar spins down. Meanwhile, the values of $R$ and $I$ would sensitively depend on the adoption of neutron star (NS) equation of state (EoS) and the NS baryonic mass. With different EoSs and baryonic masses considered, the magnetic dipole radiation luminosity ($L_{\mathrm{dip}}$) could be variant within one to two orders of magnitude. We thus suggest that when using the X-ray plateau data of GRBs to diagnose the properties of the nascent NSs, EoS and NS mass information should be invoked as simultaneously constrained parameters. On the other hand, due to the evolution of $R$ and $I$, the temporal behavior of $L_{\mathrm{dip}}$ would become more complicated. For instance, if the spin-down process is dominated by gravitational wave emission due to the NS asymmetry caused by magnetic field distortion ($\epsilon \propto B_p^2$), the segment $L_{\mathrm{dip}}\propto t^0$ could be followed by $L_{\mathrm{dip}}\propto t^{-\gamma }$ with $\gamma$ larger than 3. This case could naturally interpret the so-called internal X-ray plateau feature shown in some GRB afterglows, which means the sharp decay following the plateau is unnecessarily corresponding to the NS collapsing. This may explain why some internal X-ray plateaus are followed by late time central engine activity, manifested through flares and second shallow plateaus.

References in corpus (61)

• Collapsars - Gamma-Ray Bursts and Explosions in "Failed Supernovae"
• A unified equation of state of dense matter and neutron star structure
• The Nuclear Equation of State and Neutron Star Masses
• The Internal-Collision-Induced Magnetic Reconnection and Turbulence (ICMART) Model of Gamma-Ray Bursts
• Gamma-ray Burst Afterglow with Continuous Energy Injection: Signature of a Highly-Magnetized Millisecond Pulsar
• Electrodynamics of Magnetars: Implications for the Persistent X-ray Emission and Spindown of the Soft Gamma Repeaters and Anomalous X-ray Pulsars
• Comparing Models of Rapidly Rotating Relativistic Stars Constructed by Two Numerical Methods
• Signatures of magnetar central engines in short GRB lightcurves
• Magnetars: the physics behind observations
• Short Duration Gamma-Ray Bursts with Extended Emission from Proto-Magnetar Spin-Down
• Gravitational Waves from Neutron Stars with Large Toroidal B-fields
• Gamma-Ray Bursts and Afterglows from Rotating Strange Stars and Neutron Stars
• The prompt energy release of gamma-ray bursts using a cosmological k-correction
• Swift observations of GRB 070110: an extraordinary X-ray afterglow powered by the central engine
• Spin-Isospin Structure and Pion Condensation in Nucleon Matter
• 45 Years of Rotation of the Crab Pulsar
• Modelling magnetically deformed neutron stars
• The Millisecond Magnetar Central Engine in short GRBs
• The unusual X-ray emission of the short Swift GRB 090515: Evidence for the formation of a magnetar?
• GRB 080503: Implications of a Naked Short Gamma-Ray Burst Dominated by Extended Emission
• A test of the millisecond magnetar central engine model of GRBs with Swift data
• GRB Afterglows with Energy Injection from a spinning down NS
• Gravitational Waves from Neutron Stars: A Review
• GRB afterglow plateaus and Gravitational Waves: multi-messenger signature of a millisecond magnetar?
• Early evolution of newly born magnetars with a strong toroidal field
• Constraints on binary neutron star merger product from short GRB observations
• Mountains on Neutron Stars: Accreted vs. Non-Accreted crusts
• Magnetar powered GRBs: Explaining the extended emission and X-ray plateau of short GRB light curves
• Revised Pulsar Spindown
• Asymmetric nuclear matter and neutron star properties
• Open Questions in GRB Physics
• Can magnetar spin-down power extended emission in some short GRBs?
• Observationally constraining gravitational wave emission from short gamma-ray burst remnants
• Evolution of the Magnetic Field Structure of the Crab Pulsar
• GRB 080503 late afterglow re-brightening: signature of a magnetar powered merger-nova
• X-ray Plateaus in Gamma Ray Bursts' light-curves from jets viewed slightly off-axis
• Searching for magnetar powered merger-novae from short GRBs
• Neutron star bulk viscosity, "spin-flip" and GW emission of newly born magnetars
• The braking index of millisecond magnetars
• Structured Jets and X-ray Plateaus in Gamma-Ray Burst Phenomena
• X-ray flare candidates in short gamma-ray bursts
• Magnetar central engine and possible gravitational wave emission of nearby short GRB 160821B
• Gravitational waves or deconfined quarks: what causes the premature collapse of neutron stars born in short gamma-ray bursts?
• Imprints of r-process heating on fall-back accretion: distinguishing black hole-neutron star from double neutron star mergers
• Signature of a New-Born Black Hole from the Collapse of a Supra-massive Millisecond Magnetar
• High latitude emission from structured jet of Gamma-Ray Bursts observed off-axis
• Electromagnetic Emission from newly-born Magnetar Spin-Down by Gravitational-Wave and Magnetic Dipole Radiations
• Determining the efficiency of converting magnetar spin-down energy into gamma-ray burst X-ray afterglow emission and its possible implications
• Magnetar birth: rotation rates and gravitational-wave emission
• X-ray guided gravitational-wave search for binary neutron star merger remnants
• Evidence for magnetar precession in X-ray afterglows of gamma-ray bursts
• Gravitational waves from mountains in newly born millisecond magnetars
• Interpreting the X-ray afterglows of gamma-ray bursts with radiative losses and millisecond magnetars
• Precessing magnetars as central engines in short gamma-ray bursts
• X-ray afterglows of Short gamma-ray bursts: Magnetar or Fireball?
• Constraining the Braking Index and Energy Partition of Magnetar spindown with {\em Swift}/XRT data
• Magnetic-distortion-induced ellipticity and gravitational wave radiation of neutron stars: millisecond magnetars in short GRBs, Galactic pulsars, and magnetars
• The Second Plateau in X-ray Afterglow Providing Additional Evidence for Rapidly Spinning Magnetars as the GRB Central Engine
• Linking extended and plateau emissions of short gamma-ray bursts
• The initial evolution of millisecond magnetars: an analytical solution
• Constraining the nuclear equation of state via gravitational-wave radiation of short gamma-ray burst remnants

Cited by in corpus (2)

• Science objectives of the Einstein Probe mission
• Probing millisecond magnetar formation in binary neutron star mergers through X-ray follow-up of gravitational wave alerts