Hubble Space Telescope Detection of the Millisecond Pulsar J2124−3358 and its Far-ultraviolet Bow Shock Nebula

• Published in: The Astrophysical journal 2017-02, Vol.835 (2), p.264
• Main Authors: Rangelov, B., Pavlov, G. G., Kargaltsev, O., Reisenegger, A., Guillot, S., van Kerkwijk, M. H., Reyes, C.
• Format: Article
• Language: English
• Subjects: Astrophysics; Frequency ranges; Hubble Space Telescope; ISM: jets and outflows; Millisecond pulsars; Nebulae; Neutron flux; Neutron stars; Neutrons; Optical filters; Power law; Pulsar magnetospheres; Pulsars; pulsars: individual (PSR J2124-3358); shock waves; Space telescopes; Surface temperature; Thermal emission; ultraviolet: ISM; X-rays: individual (PSR J2124-3358)
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/835/2/264

We observed the nearby millisecond pulsar J2124-3358 with the Hubble Space Telescope in broad far-UV (FUV) and optical filters. The pulsar is detected in both bands with fluxes F(1250-2000 ) = (2.5 0.3) × 10−16 erg s−1 cm−2 and F(3800-6000 ) = (6.4 0.4) × 10−17 erg s−1 cm−2, which corresponds to luminosities of 5.8 × 1027 and 1.4 × 1027 erg s−1, for d = 410 pc and E(B − V) = 0.03. The optical-FUV spectrum can be described by a power-law model, , with slope = 0.18-0.48 for a conservative range of color excess, E(B − V) = 0.01-0.08. Since a spectral flux rising with frequency is unusual for pulsar magnetospheric emission in this frequency range, it is possible that the spectrum is predominantly magnetospheric (power law with < 0) in the optical, while it is dominated by thermal emission from the neutron star surface in the FUV. For a neutron star radius of 12 km, the surface temperature would be between 0.5 × 105 and 2.1 × 105 K for ranging from −1 to 0, E(B − V) = 0.01-0.08, and d = 340-500 pc. In addition to the pulsar, the FUV images reveal extended emission that is spatially coincident with the known H bow shock, making PSR J2124-3358 the second pulsar (after PSR J0437−4715) with a bow shock detected in the FUV.