I'm a bit puzzled and not an observer, so please bear with me if I'm being stupid here.
The code MAGPHYS specifies Jansky (Jy
) as the input unit for flux through a filter (see Section 3.2.3
in the documentation). Meaning MAGPHYS wants me to use Jy
as unit, when specify the total light of a whole galaxy in e.g. the SDSS-g band. But Jy
is a unit of spectral density, i.e. W/m²/Hz
. I would expect a flux as input unit when talking about the amont of light coming through a filter, i.e. in W/m²
or in Lodot (solar luminosity), so integrated over all frequencies that go through the filter and weighted by the filter response function.
If I have the absolute AB magnitude of a galaxy in the SDSS-g band, how do I convert it to Jy
so that MAGPHYS will be happy?
I'm aware of:
mtextABnu=−2.5log10left(fracfnu3631textJyright)qquadtextorqquadleft(fracfnutextJyright)=10−0.4(mtextABnu−8.9)
But that is in one frequency, not a whole band.
Additionally, I have found the formula below in TOPCAT:
left(fracFtextJyright)=10left(23−0.4(mtextAB+48.6)right)
Where does the 23
in the exponent come from?
No comments:
Post a Comment