A growing braking index and spin-down swings for the pulsar PSR B0540-69

Abstract

The way pulsars spin down is not understood in detail, but a number of possible physical mechanisms produce a spin-down rate that scales as a power of the rotation rate ($\dot{\nu }\propto -{\nu }^n$), with the power-law index $n$ called the braking index. PSR B0540-69 is a pulsar that in 2011, after 16 years of spinning down with a constant braking index of 2.1, experienced a giant spin-down change and a reduction of its braking index to nearly zero. Here, we show that following this episode the braking index monotonically increased during a period of at least four years and stabilised at ~1.1. We also present an alternative interpretation of a more modest rotational irregularity that occurred in 2023, which was modelled as an anomalous negative step of the rotation rate. Our analysis shows that the 2023 observations can be equally well described as a transient swing of the spin-down rate (lasting ~65 days), and the Bayesian evidence indicates that this model is strongly preferred.

arXiv comment8 pages, 3 figures, accepted for publication by ApJL

References in corpus (30)

• MultiNest: an efficient and robust Bayesian inference tool for cosmology and particle physics
• The Swift X-ray Telescope
• TEMPO2, a new pulsar timing package. I: Overview
• Switched magnetospheric regulation of pulsar spin-down
• A periodically active pulsar giving insight into magnetospheric physics
• A study of 315 glitches in the rotation of 102 pulsars
• An analysis of the timing irregularities for 366 pulsars
• 45 Years of Rotation of the Crab Pulsar
• Magnetar Spin-Down
• PINT: A Modern Software Package for Pulsar Timing
• Giant Pulses from PSR B0540-69 in the Large Magellanic Cloud
• New long-term braking index measurements for glitching pulsars using a glitch-template method
• New Phase-coherent Measurements of Pulsar Braking Indices
• Magnetic field growth in young glitching pulsars with a braking index
• High-energy characteristics of the schizophrenic pulsar PSR J1846-0258 in Kes 75
• Rotational evolution of young pulsars due to superfluid decoupling
• Neutron star glitches have a substantial minimum size
• Timing of young radio pulsars II. Braking indices and their interpretation
• The Thousand-Pulsar-Array programme on MeerKAT III: Giant pulse characteristics of PSR J0540$-$6919
• Long-term timing and emission behavior of the young Crab-like pulsar PSR B0540-69
• The brightening of the pulsar wind nebula of PSR B0540--69 after its spin-down rate transition
• A New, Low Braking Index For the LMC Pulsar B0540-69
• Discovery of a Spin-Down State Change in the LMC Pulsar B0540-69
• Long-term Radio Observations of the Intermittent Pulsar B1931+24
• Discovery of the first anti-glitch event in the rotation-powered pulsar PSR B0540-69
• The first ultraviolet detection of the Large Magellanic Cloud pulsar PSR B0540-69 and its multi-wavelength properties
• The braking index of PSR B0540-69 and the associated pulsar wind nebula emission after spin-down rate transition
• On the new braking index of PSR B0540-69: further support for magnetic field growth of neutron stars following submergence by fallback accretion
• Measuring glitch recoveries and braking indices with Bayesian model selection
• Resolving discrete pulsar spin-down states with current and future instrumentation

Cited by in corpus (2)

• Search for continuous gravitational waves from known pulsars in the first part of the fourth LIGO-Virgo-KAGRA observing run
• Narrowband searches for continuous gravitational waves from known pulsars in the first two parts of the fourth LIGO--Virgo--KAGRA observing run