The TolTEC Clouds to Cores Legacy Survey

Science Goal: The Clouds to Cores Survey will map nearby giant molecular clouds in their entirety, characterizing the core spatial distribution, properties and mass function.

Depth Goal: to achieve core mass limits (M>0.11MSolar, S1.1~0.27 mJy rms.)

Areal Coverage: 44-88 sq. deg. depending on mapping speeds

Field Priority:

  • LST group 1: Orion-A, Perseus, Orion-B, Auriga-Cal, Mon R2
  • LST group 2: Cygnus-X, Aquila-S, Aquila-N,
  • LST group 3: Ophiuchus, CepOB3,
  • Why do a C2C Survey?

    The stellar IMF is the fundamental basis of many astrophysical phenomena, from star formation rates and supernova in galaxies to the frequency of habitable planets. Despite much empirical characterization, theories for the origin of the IMF remain very poorly constrained. One current set of theories postulates that the distribution of stellar masses is inherited from the distribution of gas. This survey will map over a dozen giant molecular clouds in their entirety with sufficient depth to detect 0.05 Mʘ pre-stellar cores in all three TolTEC bands, and sufficient statistics to characterize the CMF to <0.1 Mʘ for many clouds beyond Gould’s Belt and test this theory. The substantial range of cloud properties within 2 kpc will enable the detection of any environmental effects on the CMF turnoff mass and power law index to be robustly constrained. With FWHM=5” resolution, the survey will resolve individual pre-stellar cores out to distances of 2 kpc, providing a strong statistical base for the first time to address fundamental questions such as: What is the origin of the stellar IMF? Is there an intimate link between the CMF and the IMF? Is the CMF universal?

    Image Credit: ESA/Herschel/PACS/SPIRE/Hill, Motte, HOBYS Key Programme Consortium

    Simulated core mass function sensitivity for the integrated Clouds-to-Cores survey with core numbers scaled from AzTEC observations of the MonR2 cloud (Gutermuth et al. in prep). Error bands denote 3σ uncertainties in the recovered CMF for differently scaled IMF models and are dominated by Poisson statistics for this survey.

    The relative importance of turbulence vs. magnetic fields for regulating star formation remains controversial. The polarization capabilities of TolTEC on this survey will additionally provide unique high-resolution wide-area magnetic field maps that are minimally biased toward hotter dust populations and thus well matched to the initial conditions of star formation. These sky-projected magnetic field orientation maps will probe scales from the full cloud size down to ∼0.03 pc, overlapping the size scales surveyed by Planck and BLAST-Pol and bridging the sizable gap to ALMA-scales for a wide array of clouds. This survey supersedes planned surveys from the SCUBA-2 polarimeter in depth by an order of magnitude, area by more than an order of magnitude, and angular resolution by a factor of 3. We will use the TolTEC magnetic field maps to measure cloud magnetic field strength through comparison with simulations via modern polarimetry analysis tools like histograms of relative orientations and polarization angle dispersion functions in order to address key questions like How do magnetic fields evolve as molecular clouds collapse to cores?
    Visualization of magnetic field lines in the Taurus molecular cloud, from 10´ smoothed resolution Planck 850um polarimetry (Planck Collaboration et al. 2015). These observations constrain the field strength and are used to place lower limits on the magnetic field strength. TolTEC will map magnetic fields over large sky regions with 120 times better angular resolution than these images (see lower-right panel), allowing us to extend this (and similar) techniques to higher density regimes where gravity may become dominant.