|
par1= | equivalent hydrogen column (in units of atoms cm) |
ztbabs is similar, but allows the user to set a fixed redshift parameter
par1= | equivalent hydrogen column (in units of atoms cm) |
par2= | redshift |
tbfeo is similar, but allows the user to vary the oxygen and iron abundances
par1= | equivalent hydrogen column (in units of atoms cm) |
par2= | oxygen abundance relative to Solar |
par3= | iron abundance relative to Solar |
par4= | redshift |
tbgas is similar to ztbabs but with no grain absorption
par1= | equivalent hydrogen column (in units of atoms cm) |
par2= | redshift |
tbgrain allows the user to vary the molecular hydrogen column and the grain distribution parameters.
par1 | equivalent hydrogen column (in units of atoms cm) |
par2 | fraction of hydrogen existing in molecular form as H2 |
par3 | grain density (in gm cm) |
par4 | grain minimum size (in m) |
par5 | grain maximum size (in m) |
par6 | power-law index of grain sizes |
tbpcf is similar to ztbabs but a partial covering fraction parameter
par1= | equivalent hydrogen column (in units of atoms cm) |
par2= | partial covering fraction |
par3= | redshift |
tbvarabs additionally allows the user to vary the elemental abundances and the redshift
par1 | equivalent hydrogen column (in units of atoms cm) |
par2 -par18 | abundance (relative to Solar) of He, C, N, O, Ne, Na, Mg, Al, Si, S, Cl, Ar, Ca, Cr, Fe, Co, Ni |
par19 | molecular hydrogen column (in units of atoms cm) |
par20 | grain density (in gm cm) |
par21 | grain minimum size (in m) |
par22 | grain maximum size (in m) |
par23 | power-law index of grain sizes |
par24-par41 | grain depletion fractions of He, C, N, O, Ne, Na, Mg, Al, Si, S, Cl, Ar, Ca, Cr, Fe, Co, Ni |
par42 | redshift |
tbrel is similar to tbvarabs but the interpretation of the abundances is different in that this model also allows “negative” nH. Use this, e.g., if you want to measure changes in column relative to an average column. For example, you can fit a model such as tbrel*tbabs*continuum, where all values of tbabs are frozen at the average column of the source. If the fit results in a negative column for nH during that observation, then the total column of the source is less than the average.
par1 | equivalent hydrogen column (in units of atoms cm) |
par2 -par18 | abundance (relative to Solar) of He, C, N, O, Ne, Na, Mg, Al, Si, S, Cl, Ar, Ca, Cr, Fe, Co, Ni |
par19 | molecular hydrogen column (in units of atoms cm) |
par20 | grain density (in gm cm) |
par21 | grain minimum size (in m) |
par22 | grain maximum size (in m) |
par23 | power-law index of grain sizes |
par24-par41 | grain depletion fractions of He, C, N, O, Ne, Na, Mg, Al, Si, S, Cl, Ar, Ca, Cr, Fe, Co, Ni |
par42 | redshift |
HEASARC Home | Observatories | Archive | Calibration | Software | Tools | Students/Teachers/Public
Last modified: Friday, 23-Aug-2024 13:20:40 EDT
The Astrophysics Science Division (ASD) at NASA's Goddard Space Flight Center (GSFC) seeks a creative, innovative individual with strong teamwork and leadership skills to serve as Director of the High Energy Astrophysics Science Archive Research Center (HEASARC). This will be a permanent civil servant position. + Learn more.