The magnificent seven: magnetic fields and surface temperature distributions

By F. Haberl. 2006

149 citations recorded by the source corpus.

Abstract Presently seven nearby radio-quiet isolated neutron stars discovered in ROSAT data and characterized by thermal X-ray spectra are known. They exhibit very similar properties and despite intensive searches their number remained constant since 2001 which led to their name “The Magnificent Seven”. Five of the stars exhibit pulsations in their X-ray flux with periods in the range of 3.4 s to 11.4 s. XMM-Newton observations revealed broad absorption lines in the X-ray spectra which are interpreted as cyclotron resonance absorption lines by protons or heavy ions and/or atomic transitions shifted to X-ray energies by strong magnetic fields of the order of 1013 G. New XMM-Newton observations indicate more complex X-ray spectra with multiple absorption lines. Pulse-phase spectroscopy of the best studied pulsars RX J0720.4-3125 and RBS 1223 reveals variations in derived emission temperature and absorption line depth with pulse phase. Moreover, RX J0720.4-3125 shows long-term spectral changes which are interpreted as due to free precession of the neutron star. Modeling of the pulse profiles of RX J0720.4-3125 and RBS 1223 provides information about the surface temperature distribution of the neutron stars indicating hot polar caps which have different temperatures, different sizes and are probably not located in antipodal positions.

Subfields: Astronomy and Astrophysics, Geophysics

View Paper: https://www.semanticscholar.org/paper/02c4e48908d288df441487eb3194e5b05b378dbe

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In Astronomy and Astrophysics

1. José A. Pons
2. J. Miralles
3. E. Keane
4. D. Aguilera
5. Michael Kramer
6. J. Wilms
7. Michela Mapelli
8. N. Giacobbo

In Geophysics

1. Michael Kramer
2. E. Keane
3. J. Miralles
4. José A. Pons
5. D. Aguilera

Citations in the corpus

• The SRG/eROSITA all-sky survey (2024, unknown): “…systems, these mark the graveyards of stellar evolution (see e.g. Shapiro & Teukolsky 1983; Warner 1995; Becker & Truemper 1997; Fender et al. 2004; Remillard & McClintock 2006; Haberl 2007; Özel & Freire 2016), where black holes, neutron stars, and white dwarfs accrete matter from a companion.”
• Cyclotron lines in highly magnetized neutron stars (2018, background): “New XMM-Newton observations with a factor of 2.5 more exposure confirmed this and Kaplan & van Kerkwijk (2009b) inferred a significant improvement in fit quality when including a multiplicative Gaussian line with a width of 73 eV, centered at 756 eV in the spectral model.”
• 2D Cooling of Magnetized Neutron Stars (2007, background): “However, there is increasing evidence that this is not the case for most nearby neutron stars whose termal emission is visible in the X-ray band of the electromagnetic spectrum (Zavlin 2007; Haberl 2007).”
• On the birthrates of Galactic neutron stars (2008, background): “All seven sources have determined periods with three well-known period derivatives and upper limits for three more (see tables 1 and 3 in Haberl 2007; Tiengo & Mereghetti 2007; van Kerkwijk & Kaplan 2008).”