Disk Anisotropy

Authors

Chong-Chong He (che1234 @ umd.edu)

Description

DiskAnisotropy is a program to compute anisotropy factors of radiations from accreting neutron stars, taking into account geometries effects, realistic surface radiative transfer models, and GR effects.

The underlining physics is explained in C.-C. He & L. Keek, 2016, ApJ, 819, 47 with the following additional features: (1) allowing a gap between the inner edge of the disk and the NS surface, (2) allowing GR effects

How to run

Complie the code with a simple make, or by running

gfortran -O2 -o main vectors.f95 main.f95

Then, run the executable (main). The input parameters are applied by changing the namelist file "input.nml". The program will read parameters from "input.nml", do the calculation, and print out the results on the screen. You may want to use ./main > output.out to store the outputs into a file. The code is tested with gfortran 7.2.0 on macOS 10.13.2.

Namelist

• GEOMETRY

  Parameters	Type	Default	Description
  shape	integer	1	1, 2, 3 corresponds to disk a, b, c in Fig. 1 of He & Keek 2016
  para1	real	0	If shape = 2 or 3, this is the slope of the disk surface
  diskRadius	real	4000	Disk radius in units of NS radius
  r0	real	1	Inner radius of the disk in units of NS radius. Must be in the range [1, diskRadius)
  h0	real	0	The height of the inner edge of the disk.
  los	string	'degree'	List of observational angles as 'degree' or 'cos' (the cos of the angle)

• PHYSICS

  Parameters	Type	Default	Description
  lambertian	logical	.true.	true: Lambertian surface (cos function); false: H-function surface
  GR	logical	.false.	whether or not to take into account GR effects, i.e. light bending and gravitational redshift. Current version only supports shape = 1. Note that you have to set rNS to a reasonable number before you can see GR effects.
  rNS	real	3.0	NS radius in units of gravitational radius r_g when GR is enabled. For a 1.4 solar mass NS with radius = 12 km, rNS ~ 3 rg.

TODO

1. Add GR effects to the calculation of radiation onto the disk.
2. Add GR effects to inclined disks.
3. Make h0 work in the function radiation