CARMA D+E Bulk Data Products (20 km/s channels)

This site provides the basic EDGE data products for 126 galaxies observed in both D and E arrays.  The basic properties of the data cubes are summarized in this table.

Please cite the CARMA EDGE data paper (Bolatto et al. 2017) if you use these data in presentations or publications.

Signal and Noise Cubes

These cubes were generated in MIRIAD, with CLEAN performed over an unbiased region (the field of view which extends to where the RMS noise reaches 2.5 times its minimum value).  The cubes were made with 20 km/s channels with a typical velocity range of 860 km/s.  They have been primary gain corrected and masked beyond the 50% sensitivity region.  The FITS keywords "DATE" and "DVHEL" provide the date that the cube was written and the LSR to barycentric correction in km/s.

CO
signal cube (Jy/bm) data link
1-sigma noise cube (Jy/bm) data link
2D sensitivity pattern data link
peak temperature image (mK) data link

The 2D sensitivity pattern (normalized to 1 at the field center) is useful for plotting; for example, the value=2 contour shows the field of view over which the sensitivity falls to half of its best value.  For the peak brightness temperature map, the sensitivity pattern has been divided out so units are only correct at FOV center.  This is proportional to a S/N map.

Normalized Cubes

These are the signal cubes but covering a larger field of view and with the sensitivity pattern divided out so that the noise is constant across the field. These may be appropriate for some applications where varying noise across the field would pose a problem. The gain cubes peak at 1 at the field center and fall off toward the edges. Before making flux measurements, the noise-flattened signal cube should be divided by the corresponding gain cube.

CO
noise-flattened signal cube (Jy/bm) data link
gain cube data link

Moment Maps

To generate the moment maps, the cmmsk (signal) and cmnse (noise) cubes were uncompressed and unpacked into a single directory.  At this stage, moment maps are only provided for the CO cubes.

The IDL code is freely available on Github: https://github.com/tonywong94/idl_mommaps.  The basic task to run is makemom.pro, which has a number of parameters, as can be seen in the header of the program.  Currently four sets of moment maps are generated using four different calls to makemom:

MAKEMOM,fl[k],errfile=senfl,baseroot=galname+'.'+typ+'.de20_str',senmsk=1.25,/pvmom0
MAKEMOM,fl[k],errfile=senfl,baseroot=galname+'.'+typ+'.de20_dil',thresh=3.5,edge=2,dvref=200,guard=[1,1,1],/pvmom0
MAKEMOM,fl[k],errfile=senfl,baseroot=galname+'.'+typ+'.de20_smo',thresh=3.5,edge=2,smopar=[9.,0.],dvref=200,guard=[2,2,2],/pvmom0
MAKEMOM,fl[k],errfile=senfl,baseroot=galname+'.'+typ+'.de20_mk2',maskfile=galname+'.'+typ+'.de20_smo.msk2d.fits',/pvmom0
The wrapper script to work through all of the EDGE galaxies can be found here:

The first, "straight" set of moment maps, with filenames of the form NGC5732.co.de20_str.mom0.fits, are calculated without masking and using the full velocity extent of the cube, but over a limited spatial extent (out to 1.25 times the peak sensitivity). Note that this is not optimal, since the default velocity extent is 860 km/s, and usually the signal covers a much narrow velocity range than this. One might prefer to specify a velocity range to constrain the moment calculations. The limited spatial extent is intended to reduce the flux uncertainty due to noise.

The second, "dilated" set of moment maps, with filenames of the form NGC5732.co.de20_dil.mom0.fits, uses a masking approach to exclude noise before taking moments. The mask is created by starting at 3.5-sigma (or greater) peaks in the cube and expanding down to the surrounding 2-sigma contour. An additional "guard" band of 1 pixel in all directions around the mask is added to try to capture additional low-level emission. The dvref=200 parameter specifies the velocity width (200 km/s) over which an alternative mom-0 error map (called 'emom0max') is calculated by integrating the noise cube over this range. This alternative error map can provide a rough indication of the detection limit outside the mask, where formal error estimates are unavailable.

The third, "smoothed" set of moment maps, with filenames of the form NGC5732.co.de20_smo.mom0.fits, uses pre-smoothing to enhance the signal to noise before creating a mask. The cube is spatially smoothed to a final resolution of 9", then the mask is created by starting at 3.5-sigma (or greater) peaks in the smoothed cube and expanding down to the surrounding 2-sigma contour. An additional "guard" band of 2 pixels in all directions around the mask is added to try to capture additional low-level emission. Then the mask is applied to the original, unsmoothed data cube.

The fourth, "mask2d" set of moment maps, with filenames of the form NGC5732.co.de20_mk2.mom0.fits, takes the 2-D projection of the "smoothed" mask above and applies it to every channel of the original data cube. By ensuring that every pixel gets the same number of channels, and every channel gets contributions from the same number of pixels, this provides a good way to plot a flux spectrum over a customized field of view. However, the quality of these moment maps will generally be poorer than for the "dilated" and "smoothed" maps.

The masks are best visualized using the "plots of 3D projections" linked below.

The most useful data products are moments 0, 1, and 2 and their respective errors (corresponding to integrated intensity, mean velocity, and velocity dispersion), the binary mask itself (cube of 0s and 1s), and the peak brightness within the mask. These are available for all the galaxies by following the links below. We recommend using the smoothed mask (3rd set) for moment 0 because it will capture low-level flux better. However, since higher moments are strongly influenced by the mask, the 2nd (dilated) set is recommended to estimate moments 1 and 2 at the full resolution of the data.

Straight Dilated Smoothed Mask2D
mom0+error TGZ file TGZ file TGZ file TGZ file
mom1+error TGZ file TGZ file TGZ file TGZ file
mom2+error TGZ file TGZ file TGZ file TGZ file
peak brightness TGZ file TGZ file TGZ file TGZ file
peak SNR (no masking) TGZ file
equivalent width (mom0/peak) TGZ file
binary mask cube TGZ file TGZ file TGZ file TGZ file
data for flux spectra TGZ file TGZ file TGZ file TGZ file
plots of flux spectra PDF file PDF file PDF file PDF file
plots of mom0 & mom1 PDF file PDF file PDF file PDF file
plots of 3D projections PDF file PDF file PDF file PDF file

The CSH scripts to generate the composite PDFs from the individual EPS plots are mom.csh and pv_mom.csh.

Velocity-Integrated Fluxes

An integrated flux can be obtained by summing the flux spectrum obtained using any of the four masking methods described above. A CSV file summarizing the measurements and 1-sigma errors (in Jy km/s) is provided here.


Tony Wong, 7 Nov 2017