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Last modified: December 2010

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Context: models


Spectra in the X-ray range (0.05-10 keV) emitted from a hydrogen atmosphere of a neutron star. XSpec model.


This model provides the spectra in the X-ray range (0.05-10 keV) emitted from a hydrogen atmosphere of a neutron star. There are three options:

  • nonmagnetized (B < 1e8 - 1e9 G) with a uniform surface (effective) temperature in the range of log T_eff(K) = 5.0-7.0 ;
  • a field B = 1e12 G with a uniform surface (effective) temperature in the range of log T_eff(K) = 5.5-6.8 ;
  • a field B = 1e13 G with a uniform surface (effective) temperature in the range of log T_eff(K) = 5.5-6.8 .

The atmosphere is in radiative and hydrostatic equilibrium; sources of heat are well below the atmosphere. The Comptonization effects significant at T_eff > 3e6 K) are taken into account. The model spectra are provided as seen by a distant observer, with allowance for the GR effects. The user is advised to keep M_ns and R_ns fixed and fit the temperature and the normalization. MagField must be fixed at one of 0, 1e12, or 1e13 G.

The values of the effective temperature and radius as measured by a distant observer ("values at infinity") are

T_eff^Inf = g_r*T_eff
R_ns^Inf = R_ns/g_r



This is an additive model component.

xsnsa Parameters

Number Name Description
1 logt_eff (unredshifted) effective temperature
2 m_ns neutron star gravitational mass (in units of solar mass)
3 r_ns neutron star radius (in km)
4 magfield neutron star magnetic field (0, 1e12, or 1e13 G)
5 norm K; 1/D^2, where D is the distance of the object in pc.

If you publish results obtained using this model, please reference Pavlov et al. (1992, MNRAS 253, 193) and Zavlin et al. (1996, A&A 315, 141).

XSpec version

This information is taken from the XSpec User's Guide. Version 12.6.0l of the XSpec models is supplied with CIAO 4.3.


For a list of known bugs and issues with the XSPEC models, please visit the XSPEC bugs page.

See Also

atten, bbody, bbodyfreq, beta1d, beta2d, box1d, box2d, bpl1d, const1d, const2d, cos, delta1d, delta2d, dered, devaucouleurs2d, edge, erf, erfc, exp, exp10, gauss1d, gauss2d, hubblereynolds, jdpileup, linebroad, list_model_components, list_models, log, log10, logparabola, lorentz1d, lorentz2d, models, normbeta1d, normgauss1d, poisson, polynom1d, polynom2d, powlaw1d, scale1d, scale2d, schechter, sin, sqrt, stephi1d, steplo1d, tablemodel, tan, xs, xsabsori, xsacisabs, xsapec, xsbapec, xsbbody, xsbbodyrad, xsbexrav, xsbexriv, xsbkn2pow, xsbknpower, xsbmc, xsbremss, xsbvapec, xsc6mekl, xsc6pmekl, xsc6pvmkl, xsc6vmekl, xscabs, xscemekl, xscevmkl, xscflow, xscompbb, xscompls, xscompps, xscompst, xscomptt, xsconstant, xscutoffpl, xscyclabs, xsdisk, xsdiskbb, xsdiskir, xsdiskline, xsdiskm, xsdisko, xsdiskpbb, xsdiskpn, xsdust, xsedge, xsequil, xsexpabs, xsexpdec, xsexpfac, xsezdiskbb, xsgabs, xsgaussian, xsgnei, xsgrad, xsgrbm, xshighecut, xshrefl, xskerrbb, xskerrd, xskerrdisk, xslaor, xslaor2, xslorentz, xsmeka, xsmekal, xsmkcflow, xsnei, xsnotch, xsnpshock, xsnsagrav, xsnsatmos, xsnsmax, xsnteea, xsnthcomp, xspcfabs, xspegpwrlw, xspexrav, xspexriv, xsphabs, xsplabs, xsplcabs, xsposm, xspowerlaw, xspshock, xspwab, xsraymond, xsredden, xsredge, xsrefsch, xssedov, xssmedge, xsspexpcut, xsspline, xssrcut, xssresc, xssss_ice, xsstep, xsswind1, xstbabs, xstbgrain, xstbvarabs, xsuvred, xsvapec, xsvarabs, xsvbremss, xsvequil, xsvgnei, xsvmcflow, xsvmeka, xsvmekal, xsvnei, xsvnpshock, xsvphabs, xsvpshock, xsvraymond, xsvsedov, xswabs, xswndabs, xsxion, xszbbody, xszbremss, xszdust, xszedge, xszgauss, xszhighect, xszpcfabs, xszphabs, xszpowerlw, xszredden, xszsmdust, xsztbabs, xszvarabs, xszvfeabs, xszvphabs, xszwabs, xszwndabs, xszxipcf

Last modified: December 2010
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