FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45-m telescope
Background
Recently, high angular resolution continuum surveys of the Galactic plane such as
GLIMPS & MIPSGAL by Spitzer, Hi-GAL by Herschel and AKARI have been carried out
at the mid- and far-infrared. Submm surveys of Galactic plane were also conducted
by some groups, such as ATLASGAL, BGPS and SUCUBA-2 surveys.
These surveys made a great contribution to identify star forming activity, and
revealed detailed structure of molecular clouds, filaments and dense clumps thought
to be sites of massive star and cluster formation but they lack the velocity
information. On the other hand, 3-dimensional data obtained by observations of
spectral lines provide crucial information to reveal their dynamical state and
interaction of molecular clouds. Therefor, Survey of the Galactic plane in spectral
lines with wide coverage and enough angular resolution to comparable to the IR
surveys are highly required.
FUGIN Project
Recent improvement of surface accuracy of the Nobeyama 45-m Telescope and the
new multi-beam receiver "FOREST" realized large-scale mapping observations of the
Galactic plane with high angular resolution within a short time. That is ”FUGIN”
(FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45-m telescope).
Using the multi-beam receiver FOREST, we will carry out OTF mapping of the Galactic
plane and the outer disk in 12CO, 13CO, and C180 J=1-0 transition, simultaneously.
This is the CO Galactic Plane Survey by simultaneous 3 CO lines with the highest
angular resolution(-20”). Moreover, we can resolve structures of both diffuse gas
and dense gas in molecular clouds at once by simultaneous 3 CO J=1-0 lines
tracing different density regions.
Observing strategy
Mapping area
- 1st quadrant l: 10° -50° b: ±1°(80 deg2)
(inner disk: spiral arms, interarm, bar/barend) - 3rd quadrant l: 198°-236° b: ±1° (76 deg2)
(outer disk: comparison with inner disk)
Observation Plan
- Lines: 12CO, 13CO, C18O J=1-0 (simultaneously)
- SAM45 spectrometer: BW=1000MHz, 4096ch
- Simultaneous 12CO, 13CO, C18O observations
- Velocity resolution: 1.3 km/s (df=244.14kHz-->0.65 km/s)
- Scans: the 1st quadrant: X and Y scans, the 3rd quadrant: X scan
Target Sensitivity
- Trms(Ta*) =0.12K @13CO dv= 1.3 km/s @Tsys=150K
- Trms(Ta*) =0.12K @12CO dv= 5 km/s (-0.24 K dv=1.3 km/s) @Tsys=250K
See Umemoto, T. et al. 2017, PASJ, 69, 78