The first ultraviolet detection of the Large Magellanic Cloud pulsar PSR B0540-69 and its multi-wavelength properties

Abstract

We observed the young ($\sim 1700$ yrs) pulsar PSR B0540-69 in the near-ultraviolet (UV) for the first time with the Space Telescope Imaging Spectrograph (STIS) aboard the {\em Hubble Space Telescope}. Imaging observations with the NUV- and FUV-MAMA detectors in TIME-TAG mode allowed us to clearly detect the pulsar in two bands around 2350Å and 1590Å, with magnitudes $m_{\mathrm{NUV}}=21.449\pm 0.019$ and $m_{\mathrm{FUV}}=21.832\pm 0.103$. We also detected the pulsar-wind nebula (PWN) in the NUV-MAMA image, with a morphology similar to that observed in the optical and near-infrared (IR). The extinction-corrected NUV and FUV pulsar fluxes are compatible with a very steep power law spectrum $F_{\nu }\propto {\nu }^{-\alpha }$ with spectral index ${\alpha }_{\mathrm{UV}}\sim 3$, non compatible with a Rayleigh Jeans spectrum, indicating a non-thermal origin of the emission. The comparison with the optical/near-IR power-law spectrum (spectral index ${\alpha }_{\mathrm{O},\mathrm{nIR}}\sim 0.7$), indicates an abrupt turn-off at wavelengths below 2500 Å, not observed in other pulsars. We detected pulsations in both the NUV and FUV data at the 50 ms pulsar period. In both cases, the pulse profile features two peaks closely spaced in phase, as observed in the optical and X-ray light curves. The NUV/FUV peaks are also aligned in phase with those observed in the radio (1.4 GHz), optical, X, and $\gamma$-ray light curves, like in the Crab pulsar, implying a similar beaming geometry across all wavelengths. PSR B0540-69 is now the fifth isolated pulsar, together with Crab, Vela, PSR\, B0656+14, and the radio-quiet Geminga, detected in the optical, near-UV, near-IR, X-rays and $\gamma$-rays, and seen to pulsate in at least four of these energy bands.

33 pages, 6 figures, accepted for publication on ApJ

References in corpus (16)

• The ATNF Pulsar Catalogue
• TEMPO2, a new pulsar timing package. I: Overview
• Precise Gamma-Ray Timing and Radio Observations of 17 Fermi Gamma-Ray Pulsars
• Optical polarisation of the Crab pulsar: precision measurements and comparison to the radio emission
• Hubble Space Telescope detection of the millisecond pulsar J2124-3358 and its far-ultraviolet bow shock nebula
• Optical and infrared observations of the Crab Pulsar and its nearby knot
• Old but still warm: Far-UV detection of PSR B0950+08
• A New, Low Braking Index For the LMC Pulsar B0540-69
• UV emission from young and middle-aged pulsars: Connecting X-rays with the optical
• Discovery of a Spin-Down State Change in the LMC Pulsar B0540-69
• Studies of Neutron Stars at Optical/IR Wavelengths
• The first detection of a pulsar with ALMA
• Toward understanding the physical underpinnings of spatial and spectral morphologies of pulsar wind nebulae
• HST multi-epoch imaging of the PSR B0540-69 system unveils a highly dynamic synchrotron nebula
• Observations of three young gamma-ray pulsars with the Gran Telescopio Canarias
• Timing analysis and pulse profile of the Vela pulsar in the optical band from Iqueye observations

Cited by in corpus (13)

• The brightening of the pulsar wind nebula of PSR B0540--69 after its spin-down rate transition
• Synchro-curvature modelling of the multi-frequency non-thermal emission of pulsars
• Optical and ultraviolet pulsed emission from an accreting millisecond pulsar
• Utilizing cosmic-ray positron and electron observations to probe the averaged properties of Milky Way pulsars
• Atacama Compact Array Observations of the Pulsar-Wind Nebula of SNR 0540-69.3
• Hubble Space Telescope observations of the old pulsar PSR J0108-1431
• PSR B0656+14: the unified outlook from the infrared to X-rays
• Kinematics, structure and abundances of supernova remnant 0540-69.3
• Spatial Variations and Breaks in the Optical-NIR spectra of the Pulsar and PWN in SNR 0540-69.3
• A growing braking index and spin-down swings for the pulsar PSR B0540-69
• Possible counterpart signal of the Fermi bubbles at the cosmic-ray positrons
• Search of nearby resolved neutron stars among optical sources
• Gamma-ray flares from pulsar wind nebulae in the Large Magellanic Cloud