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Chandra X-ray Observations of Nineteen Millisecond Pulsars in the Globular Cluster 47 Tucanae
| Content Provider | Semantic Scholar |
|---|---|
| Author | Bogdanov, Slavko Grindlay, Jonathan E. Heinke, Craig O. Camilo, Fernando Rossi Freire, Paulo De Tarso Cavalcante Becker, Werner |
| Copyright Year | 2008 |
| Abstract | We present spectral and long-timescale variability analyses of Chandra X-ray Observatory ACISS observations of the 19 millisecond pulsars (MSPs) with precisely known positions in the globular cluster 47 Tucanae. The X-ray emission of the majority of these MSPs is well described by a thermal (blackbody or neutron star hydrogen atmosphere) spectrum with a temperature Teff ∼ (1 − 3) × 10 K, emission radius Reff ∼ 0.1−3 km, and luminosity LX ∼ 10 ergs s. For several MSPs, there is indication that a second thermal component is required, similar to what is seen in some nearby field MSPs. The observed radiation most likely originates from the heated magnetic polar caps of the MSPs. The small apparent scatter in LX is consistent with thermal emission from the polar caps of a global dipole field although the small emission areas may imply either a more complex small-scale magnetic field configuration near the neutron star surface or non-uniform polar cap heating. The radioeclipsing binary MSPs 47 Tuc J, O, and W show a significant non-thermal (power-law) component, with spectral photon index Γ ∼ 1 − 1.5, which most likely originates in an intrabinary shock formed due to interaction between the relativistic pulsar wind and matter from the stellar companion. We re-examine the X-ray–spindown luminosity relation (LX −Ė) and find that for the MSPs with thermal spectra LX ∝ Ė , where β ∼ 0.2 ± 1.1. Due to the large uncertainties in both parameters the result is consistent with both the linear LX − Ė relation and the flatter LX ∝ Ė predicted by polar cap heating models. In terms of X-ray properties, we find no clear systematic differences between MSPs in globular clusters and in the field of the Galaxy. We discuss the implications of these results of the present understanding of the X-ray emission properties of MSPs. Subject headings: globular clusters: general — globular clusters: individual (47 Tucanae) — pulsars: general — stars: neutron — X-rays: stars |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://arxiv.org/pdf/astro-ph/0604318v1.pdf |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Diagnostic radiologic examination Eragrostis GUCY2C protein, human Heating Hewlett-Packard 95LX Hydrogen Magnetic Fields Medical Subject Headings Neutrons Photons Rajiformes Shock Spatial variability Stars, Celestial Stellar (payment network) Thermal grease X-Ray (Amazon Kindle) |
| Content Type | Text |
| Resource Type | Article |
