A Galactic Molecular Cloud Clump Catalog from Hi-GAL Data: Method and Initial Results Comparison to BGPS

Abstract

As the precursors to stellar clusters, it is imperative that we understand the distribution and physical properties of dense molecular gas clouds and clumps. Such a study has been done with the ground-based Bolocam Galactic Plane Survey (BGPS). Now the Herschel infrared GALactic plane survey (Hi-GAL) allows us to do the same with higher quality data and complete coverage of the Galactic plane. We have made a pilot study comparing dense molecular gas clumps identified in the Hi-GAL and BGPS surveys, using six $2^{\circ }\times 2^{\circ }$ regions centered at Galactic longitudes of $\ell =11^{\circ }$, 30${}^{\circ }$, 41${}^{\circ }$, 50${}^{\circ }$, 202${}^{\circ }$, and $217^{\circ }$. We adopted the BGPS methodology for identifying clumps and estimating distances, leading to 6198 clumps being identified in our substudy, with 995 of those having well-constrained distances. These objects were evenly distributed with Galactic longitude, a consequence of Hi-GAL being source confusion limited. These clumps range in mass from 10${}^{-2}$ M${}_{\odot }$ to 10${}^5$ M${}_{\odot }$, and have heliocentric distances of up to 16 kpc. When clumps found in both surveys are compared, we see that distances agree within 1 kpc and ratios of masses are of order unity. This serves as an external validation for BGPS and instills confidence as we move forward to cataloging the clumps from the entirety of Hi-GAL. In addition to the sources that were in common with BGPS, Hi-GAL found many additional sources, primarily due to the lack of atmospheric noise. We expect Hi-GAL to yield $2\times 10^5$ clumps, with 20% having well-constrained distances, an order of magnitude above what was found in BGPS.

arXiv comment26 pages, 12 figures, 3 tables; published in the Astrophysical Journal

References in corpus (45)

• Star Formation in the Milky Way and Nearby Galaxies
• Theory of Star Formation
• The Photodetector Array Camera and Spectrometer (PACS) on the Herschel Space Observatory
• The Herschel-SPIRE instrument and its in-flight performance
• Galaxies on FIRE (Feedback In Realistic Environments): Stellar Feedback Explains Cosmologically Inefficient Star Formation
• Trigonometric Parallaxes of High Mass Star Forming Regions: the Structure and Kinematics of the Milky Way
• The Neutral Atomic Phases of the ISM in the Galaxy
• The Stellar IMF from Turbulent Fragmentation
• Cold Dark Clouds: The Initial Conditions for Star Formation
• Cosmological Simulations with TreeSPH
• ATLASGAL - The APEX Telescope Large Area Survey of the Galaxy at 870 microns
• Hi-GAL: the Herschel infrared Galactic Plane Survey
• The Universality of the Stellar IMF
• Making Galaxies in a Cosmological Context: The Need for Early Stellar Feedback
• Physical Properties and Galactic Distribution of Molecular Clouds identified in the Galactic Ring Survey
• The initial conditions of stellar protocluster formation. I. A catalogue of Spitzer dark clouds
• The Bolocam Galactic Plane Survey: Survey Description and Data Reduction
• The AGORA High-Resolution Galaxy Simulations Comparison Project
• Hi-GAL, the Herschel infrared Galactic Plane Survey: photometric maps and compact source catalogues. First data release for Inner Milky Way: +68°> l > -70°
• The Bolocam Galactic Plane Survey -- II. Catalog of the Image Data
• Kinematic Distances to Molecular Clouds identified in the Galactic Ring Survey
• The ATLASGAL survey: a catalog of dust condensations in the Galactic plane
• Galaxies in a Simulated $\Lambda$CDM Universe II: Observable Properties and Constraints on Feedback
• A Catalog of MSX Infrared Dark Cloud Candidates
• Resolution of the Distance Ambiguity for Galactic HII Regions
• MALT90: The Millimetre Astronomy Legacy Team 90 GHz Survey
• Characterizing Precursors to Stellar Clusters with Herschel
• The Bolocam Galactic Plane Survey IX: Data Release 2 and Outer Galaxy Extension
• The Bolocam Galactic Plane Survey. VII. Characterizing the Properties of Massive Star-Forming Regions
• The first Hi-GAL observations of the outer Galaxy: a look to star formation in the third Galactic quadrant in the longitude range 216.5 < l < 225.5
• ATLASGAL - Kinematic distances and the dense gas mass distribution of the inner Galaxy
• Molecular clouds and clumps in the Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
• Variations in the Stellar IMF: from Bottom to Top
• BLAST: The Mass Function, Lifetimes, and Properties of Intermediate Mass Cores from a 50 Square Degree Submillimeter Galactic Survey in Vela (l = ~265)
• The ATLASGAL survey: distribution of cold dust in the Galactic plane. Combination with Planck data
• A self-consistent model of Galactic stellar and dust infrared emission and the abundance of polycyclic aromatic hydrocarbons
• Physical properties of high-mass clumps in different stages of evolution
• A statistical study of the mass and density structure of Infrared Dark Clouds
• The Bolocam Galactic Plane Survey. VIII. A Mid-Infrared Kinematic Distance Discrimination Method
• Distribution and characteristics of Infrared Dark Clouds using genetic forward modelling
• The Bolocam Galactic Plane Survey. XII. Distance Catalog Expansion Using Kinematic Isolation of Dense Molecular Cloud Structures With 13CO(1-0)
• Do Lognormal Column-Density Distributions in Molecular Clouds Imply Supersonic Turbulence?
• Clump mass function at an early stage of molecular cloud evolution: I. A statistical approach
• Clump mass function at an early stage of molecular cloud evolution: II. Galactic cloud complexes
• The mass distribution of clumps within infrared dark clouds. A Large APEX Bolometer Camera study

Cited by in corpus (2)

• Northern Galactic Molecular Cloud Clumps in Hi-GAL: Clump and Star Formation within Clouds
• Northern Galactic Molecular Cloud Clumps in Hi-GAL: Dense Gas Map and Environmental Trends