A Legacy program to utilize HAWC+ to map the central region of the Galaxy at 214 µm utilizing the shared-risk scan mode polarimetry observing strategy.
The resulting data product yields a transformative data set for understanding the magnetic fields in the cool dust ring in the central 200 pc.
Such a data set would elucidate the role of the magnetic field in Galactic center dynamics from the 200 pc scale down to scales below a parsec.
Approximate coverage of the FIREPLACE survey, in Galactic coordinates, with prominent CMZ molecular clouds labelled (based on Figure 2 of Paré+2024):
The FIRPLACE data products are provided in two types: the observations of each field, and a merged image covering the entire inner galaxy.
INDIVIDUAL FIELDS
The FIREPLACE survey is comprised of separate SOFIA/HAWC+ observation fields.
We provide CRUSH-reduced CAL files for each of the observation fields where CRUSH was run using the following parameters: “-rounds=85 -downsample=1 -fixjumps=True -extended”.
The CAL FITS files are comprised of the following extensions:
0
STOKES
I
PrimaryHDU
1
ERROR
I
ImageHDU
2
STOKES
Q
ImageHDU
3
ERROR
Q
ImageHDU
4
STOKES
U
ImageHDU
5
ERROR
U
ImageHDU
6
COVAR
Q-I
ImageHDU
7
COVAR
U-I
ImageHDU
8
COVAR
Q-U
ImageHDU
9
BAD PIXEL MASK
ImageHDU
Stokes I measures the total intensity and Stokes Q / U measure linear polarization. Other extensions contain the errors and covariances on these Stokes parameters with a last extension indicating the mask of bad pixels.
These distributions are in equatorial (Right Ascension, Declination) coordinates.
The entire survey is a CMZ-wide map created by combining the individual CAL files using the SOFIA DRP software "merge" algorithm. The extensions of this merged file are:
0
STOKES
PrimaryHDU
1
ERROR
ImageHDU
2
STOKES
ImageHDU
3
ERROR
ImageHDU
4
STOKES
ImageHDU
5
ERROR
ImageHDU
6
IMAGE
ImageHDU
7
PERCENT
ImageHDU
8
DEBIASED PERCENT POL
ImageHDU
9
ERROR PERCENT POL
ImageHDU
10
POL ANGLE
ImageHDU
11
ROTATED POL ANGLE
ImageHDU
12
ERROR POL ANGLE
ImageHDU
13
POL FLUX
ImageHDU
14
ERROR POL FLUX
ImageHDU
15
DEBIASED POL FLUX
ImageHDU
16
POL DATA
BinTableHDU
17
FINAL POL DATA
BinTableHDU
Of particular relevance are the percentage polarization (extension 7), polarization angle (extension 10), the debiased percentage polarization (extension 8), and the rotated polarization angle,
which is the magnetic field orientation (extension 11). Note that these distributions are in the equatorial coordinate system.
