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nsmaxg: neutron star with a magnetic atmosphere

 

The nsmaxg model interpolates from a grid of neutron star (NS) atmosphere spectra to produce a final spectrum that depends on the parameters listed below. Atmosphere spectra are obtained using the latest equation of state and opacity results for a partially ionized, strongly magnetized hydrogen or mid-Z element plasma. Models are constructed by solving the coupled radiative transfer equations for the two photon polarization modes in a magnetized medium, and the atmosphere is in radiative and hydrostatic equilibrium. Atmosphere models mainly depend on the surface effective temperature Teff and magnetic field strength B and inclination ΘB; there is also a dependence on the surface gravity g=(1+zg)GM/R2, where 1+zg=(1-2GM/R)-1/2 is the gravitational redshift and M and R are the NS mass and radius, respectively.

 

Two sets of models are available: one set with a single surface B and Teff [some models allow for varying g, in the range log g (cm s-2) = 13.6-15.4] and a set which is constructed with B and Teff varying across the surface according to the magnetic dipole model (θm is the angle between the direction to the observer and the magnetic axis). Effective temperatures span the range log Teff (K) ≈ 5.5-6.7. Models with single (B,Teff) cover the energy range 0.05-10 keV, while models with (B,Teff)-distributions cover the range 0.09-5 keV.

The parameters are:

 

par1

log Teff, surface (unredshifted) effective temperature

par2

M, neutron star gravitation mass (in units of Solar mass)

par3

R, neutron star radius (in km)

par4

d, distance to neutron star (in kpc)

par5

Switch indicating model to  use

norm

1, normalization (though not strictly correct, can be varied to change the size of the emission region, (Rem/R)2)

 

The models available by setting par5 are:

 

Switch

Element

B(1012 G)

ΘB

θm

log g (cm/s2)

log Teff

E (keV)

1000

H

0.01

0

N/A

2.4

5.5 - 6.7

0.05 - 10

1060

H

0.04

0

N/A

2.4

5.5 - 6.7

0.05 - 10

1085

H

0.07

0

N/A

2.4

5.5 - 6.7

0.05 - 10

1100

H

0.1

0

N/A

2.4

5.5 - 6.7

0.05 - 10

1200

H

1.0

0

N/A

0.4 - 2.5

5.5 - 6.7

0.05 - 10

1230

H

2.0

0

N/A

2.4

5.5 - 6.8

0.05 - 10

1260

H

4.0

0

N/A

2.4

5.5 - 6.8

0.05 - 10

1280

H

7.0

0

N/A

2.4

5.5 - 6.8

0.05 - 10

1300

H

10.0

0

N/A

0.4 - 2.5

5.5 - 6.7

0.05 - 10

1330

H

20.0

0

N/A

2.4

5.6 - 6.8

0.05 - 10

1350

H

30.0

0

N/A

2.4

5.7 - 6.8

0.05 - 10

1211

H

1.26

0

N/A

1.6

5.5 - 6.8

0.05 - 10

1281

H

7.0

0

N/A

1.6

5.5 - 6.8

0.05 - 10

12006

C

1.0

0

N/A

2.4

5.8 - 6.9

0.05 - 10

13006

C

10.0

0

N/A

2.4

5.8 - 6.9

0.05 - 10

12008

O

1.0

0

N/A

2.4

5.8 - 6.9

0.05 - 10

13008

O

10.0

0

N/A

2.4

5.8 - 6.9

0.05 - 10

12010

Ne

1.0

0

N/A

2.4

5.8 - 6.9

0.05 - 10

13010

Ne

10.0

0

N/A

2.4

5.8 - 6.9

0.05 - 10

123100

H

1.0 - 1.82

0-90

0

1.6

5.5 - 6.8

0.09 - 5

123190

H

1.0 - 1.82

0-90

90

1.6

5.5 - 6.8

0.09 - 5

130100

H

5.5 - 10.0

0-90

0

1.6

5.5 - 6.8

0.09 - 5

130190

H

5.5 - 10.0

0-90

90

1.6

5.5 - 6.8

0.09 - 5

 

If you publish results obtained using nsmaxg, please reference Ho, W.C.G., Potekhin, A.Y., & Chabrier, G. (2008, ApJS, 178, 102) and also Mori, K. & Ho, W.C.G. (2007, MNRAS, 377, 905) if using mid-Z models. See Ho, W.C.G. (2014, Proc. of IAUS 302, submitted) for discussion of nsmaxg and nsmax.

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Next: Nsx Up: Additive Model Components Previous: NSmax