The Bolocam Galactic Plane Survey. II. Catalog of the Image Data (original) (raw)
Related papers
The Bolocam Galactic Plane Survey: Survey Description and Data Reduction
Astrophysical Journal Supplement Series, 2011
We present the Bolocam Galactic Plane Survey (BGPS), a 1.1 mm continuum survey at 33'' effective resolution of 170 deg2 of the Galactic Plane visible from the northern hemisphere. The BGPS is one of the first large area, systematic surveys of the Galactic Plane in the millimeter continuum without pre-selected targets. The survey is contiguous over the range -10.5 <= l <= 90.5, |b| <= 0.5. Toward the Cygnus X spiral arm, the coverage was flared to |b| <= 1.5 for 75.5 <= l <= 87.5. In addition, cross-cuts to |b| <= 1.5 were made at l= 3, 15, 30, and 31. The total area of this section is 133 deg2. With the exception of the increase in latitude, no pre-selection criteria were applied to the coverage in this region. In addition to the contiguous region, four targeted regions in the outer Galaxy were observed: IC1396 (9 deg2, 97.5 <= l <= 100.5, 2.25 <= b <= 5.25), a region toward the Perseus Arm (4 deg2 centered on l = 111, b = 0 near NGC 7538), W3/4/5 (18 deg2, 132.5 <= l <= 138.5), and Gem OB1 (6 deg2, 187.5 <= l <= 193.5). The survey has detected approximately 8400 clumps over the entire area to a limiting non-uniform 1σ noise level in the range 11-53 mJy beam-1 in the inner Galaxy. The BGPS source catalog is presented in a previously published companion paper. This paper details the survey observations and data reduction methods for the images. We discuss in detail the determination of astrometric and flux density calibration uncertainties and compare our results to the literature. Data processing algorithms that separate astronomical signals from time-variable atmospheric fluctuations in the data timestream are presented. These algorithms reproduce the structure of the astronomical sky over a limited range of angular scales and produce artifacts in the vicinity of bright sources. Based on simulations, we find that extended emission on scales larger than about 5farcm9 is nearly completely attenuated (>90%) and the linear scale at which the attenuation reaches 50% is 3farcm8. Comparison with other millimeter-wave data sets implies a possible systematic offset in flux calibration, for which no cause has been discovered. This presentation serves as a companion and guide to the public data release (http://irsa.ipac.caltech.edu/Missions/bolocam.html) through NASA's Infrared Processing and Analysis Center (IPAC) Infrared Science Archive (IRSA). New data releases will be provided through IPAC-IRSA with any future improvements in the reduction. The BGPS provides a complementary long-wavelength spectral band for the ongoing ATLASGAL and Herschel-SPIRE surveys, and an important database and context for imminent observations with SCUBA-2 and ALMA.
A Mid-Infrared Census of Star Formation Activity in Bolocam Galactic Plane Survey Sources
The Astrophysical …, 2011
We present the results of a search for mid-infrared signs of star formation activity in the 1.1 mm sources in the Bolocam Galactic Plane Survey (BGPS). We have correlated the BGPS catalog with available mid-IR Galactic plane catalogs based on the Spitzer Space Telescope GLIMPSE legacy survey and the Midcourse Space Experiment (MSX ) Galactic plane survey. We find that 44% (3,712 of 8,358) of the BGPS sources contain at least one mid-IR source, including 2,457 of 5,067 (49%) within the area where all surveys overlap (10 • < ℓ < 65 • ). Accounting for chance alignments between the BGPS and mid-IR sources, we conservatively estimate that 20% of the BPGS sources within the area where all surveys overlap show signs of active star formation. We separate the BGPS sources into four groups based on their probability of star formation activity. Extended Green Objects (EGOs) and Red MSX Sources (RMS) make up the highest probability group, while the lowest probability group is comprised of "starless" BGPS sources which were not matched to any mid-IR sources. The mean 1.1 mm flux of each group increases with increasing probability of active star formation. We also find that the "starless" BGPS sources are the most compact, while the sources with the highest probability of star formation activity are on average more extended with large skirts of emission. A subsample of 280 BGPS sources with known distances demonstrates that mass and mean H 2 column density also increase with probability of star formation activity.
Astrophysical Journal, 2010
We present the 1.1 millimeter Bolocam Galactic Plane Survey (BGPS) observations of the Gemini OB1 molecular cloud complex, and targeted NH 3 observations of the BGPS sources. When paired with molecular spectroscopy of a dense gas tracer, millimeter observations yield physical properties such as masses, radii, mean densities, kinetic temperatures and line widths. We detect 34 distinct BGPS sources above 5σ = 0.37 Jy beam −1 with corresponding 5σ detections in the NH 3 (1,1) transition. Eight of the objects show water maser emission (20%). We find a mean millimeter source FWHM of 1.12 pc, and a mean gas kinetic temperature of 20 K for the sample of 34 BGPS sources with detections in the NH 3 (1,1) line. The observed NH 3 line widths are dominated by non-thermal motions, typically found to be a few times the thermal sound speed expected for the derived kinetic temperature. We calculate the mass for each source from the millimeter flux assuming the sources are isothermal and find a mean isothermal mass within a 120 ′′ aperture of 230 ± 180 M ⊙ . We find a total mass of 8,400 M ⊙ for all BGPS sources in the Gemini OB1 molecular cloud, representing 6.5% of the cloud mass. By comparing the millimeter isothermal mass to the virial mass within a radius equal to the mm source size calculated from the NH 3 line widths, we find a mean virial parameter (M vir /M iso ) of 1.0±0.9 for the sample. We find mean values for the distributions of column densities of 1.0 × 10 22 cm −2 for H 2 , and 3.0 × 10 14 cm −2 for NH 3 , giving a mean NH 3 abundance of 3.0 × 10 −8 relative to H 2 . We find volume-averaged densities on the order of 10 3 − 10 4 cm −3 . The sizes and densities suggest that in the Gem OB 1 region the BGPS is detecting the clumps from which stellar clusters form, rather than smaller, higher density cores where single stars or small multiple systems form.
2005
We present results from a survey of a 1300 arcmin^2 region of the Orion B South molecular cloud, including NGC 2024, NGC 2023, and the Horsehead Nebula (B33), obtained using the Submillimetre Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope. Submillimeter continuum observations at 450 microns and 850 microns are discussed. Using an automated algorithm, 57 discrete emission features (``clumps'') are identified in the 850 micron map. The physical conditions within these clumps are investigated under the assumption that the objects are in quasi-hydrostatic equilibrium. The best fit dust temperature for the clumps is found to be T_d = 18 +/- 4 K, with the exception of those associated with the few known far infrared sources residing in NGC 2024. The latter internally heated sources are found to be much warmer. In the region surrounding NGC 2023, the clump dust temperatures agree with clump gas temperatures determined from molecular line excitation measure...
The Astrophysical Journal, 2001
We present results from a survey of a 900 arcmin2 region of the Orion B molecular cloud, including NGC 2068, NGC 2071, and HH 24/25/26, at 850 km using the Submillimeter Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope. Following the techniques developed by Johnstone et al., we identify 75 independent objects and compute size, Ñux, and degree of central concentration. Comparison with isothermal, pressure-conÐned, self-gravitating Bonnor-Ebert spheres implies that the clumps have internal temperatures of 20È40 K and surface pressures 5.5 \ log P/k \ 6.5. The clump masses span 0.2È12.3 assuming typical dust temperatures and a dust emissivity cm2 g~1. M _ i 850 \ 0.01 The distribution of clump masses is well characterized by a power-law N(M) P M~a with a \ 1.5È2.0 for M [ 1.0 SigniÐcant incompleteness makes determination of the slope at lower masses difficult. The M _. two-point correlation function of the clump separations is measured revealing clustering on size scales r \ 1.5 ] 105 AU with a radial power-law exponent c \ 0.75.
The UKIDSS Galactic Plane Survey
Monthly Notices of the Royal Astronomical Society, 2008
The UKIDSS Galactic Plane Survey (GPS) is one of the five near infrared Public Legacy Surveys that are being undertaken by the UKIDSS consortium, using the Wide Field Camera on the United Kingdom Infrared Telescope. It is surveying 1868 deg 2 of the northern and equatorial Galactic plane at Galactic latitudes −5 • < b < 5 • in the J, H and K filters and a ∼ 200 deg 2 area of the Taurus-Auriga-Perseus molecular cloud complex in these three filters and the 2.12 µm (1-0) H 2 filter. It will provide data on ∼ 2 × 10 9 sources. Here we describe the properties of the dataset and provide a user's guide for its exploitation. We also present brief Demonstration Science results from DR2 and from the Science Verification programme. These results illustrate how GPS data will frequently be combined with data taken in other wavebands to produce scientific results. The Demonstration Science comprises six studies. (1) A GPS-Spitzer-GLIMPSE cross match for the star formation region G28.983-0.603 to identify YSOs. This increases the number of YSOs identified by a factor of ten compared to GLIMPSE alone. (2) A wide field study of the M17 nebula, in which an extinction map of the field is presented and the effect of source confusion on luminosity functions in different sub-regions is noted. (3) H 2 emission in the ρ Ophiuchi dark cloud. All the molecular jets are traced back to a single active clump containing only a few protostars, which suggests that the duration of strong jet activity and associated rapid accretion in low mass protostars is brief. (4) X-ray sources in the Nuclear Bulge. The GPS data distinguishes local main sequence counterparts with soft X-ray spectra from Nuclear Bulge giant counterparts with hard X-ray spectra. (5) External galaxies in the Zone of Avoidance. The galaxies are clearly distinguished from stars in fields at longitudes l>90 • . (6) IPHAS-GPS optical-infrared spectrophotometric typing. The (i'-J) vs.(J-H) diagram is used to distinguish A-F type dwarfs, G dwarfs, K dwarfs and red clump giants in a field with high reddening.
Bird’s eye view of molecular clouds in the Milky Way
Astronomy and Astrophysics, 2021
Context. Describing how the properties of the interstellar medium are combined across various size scales is crucial for understanding star formation scaling laws and connecting Galactic and extragalactic data of molecular clouds. Aims. We describe how the statistical structure of the clouds and its connection to star formation changes from sub-parsec to kiloparsec scales in a complete region within the Milky Way disk. Methods. We built a census of molecular clouds within 2 kpc from the Sun using data from the literature. We examined the dust-based column density probability distributions (N-PDFs) of the clouds and their relation to star formation as traced by young stellar objects (YSOs). We then examined our survey region from the outside, within apertures of varying sizes, and describe how the N-PDFs and their relation to star formation changes with the size scale. Results. We present a census of the molecular clouds within 2 kpc distance, including 72 clouds and YSO counts for 44 of them. The N-PDFs of the clouds are not well described by any single simple model; use of any single model may bias the interpretation of the N-PDFs. The top-heaviness of the N-PDFs correlates with star formation activity, and the correlation changes with Galactic environment (spiral-and inter-arm regions). We find that the density contrast of clouds may be more intimately linked to star formation than the dense gas mass fraction. The aperture-averaged N-PDFs vary with the size scale and are more top-heavy for larger apertures. The top-heaviness of the aperture N-PDFs correlates with star formation activity up to roughly 0.5 kpc, depending on the environment. Our results suggest that the relations between cloud structure and star formation are environment specific and best captured by relative quantities (e.g. the density contrast). Finally, we show that the density structures of individual clouds give rise to a kiloparsec-scale Kennicutt-Schmidt relation as a combination of sampling effects and blending of different galactic environments.
Monthly Notices of the Royal Astronomical Society, 2013
We combine Planck High Frequency Instrument data at 857, 545, 353 and 217 GHz with data from Wide-field Infrared Survey Explorer (WISE), Spitzer, IRAS and Herschel to investigate the properties of a well-defined, flux-limited sample of local star-forming galaxies. A 545 GHz flux density limit was chosen so that the sample is 80 per cent complete at this frequency, and the resulting sample contains a total of 234 local, star-forming galaxies. We investigate the dust emission and star formation properties of the sample via various models and calculate the local dust mass function. Although single-component-modified blackbodies fit the dust emission longward of 80 μm very well, with a median β = 1.83, the known degeneracy between dust temperature and β also means that the spectral energy distributions are very well described by a dust component with dust emissivity index fixed at β = 2 and temperature in the range 10-25 K. Although a second, warmer dust component is required to fit shorter wavelength data, and contributes approximately a third of the total infrared emission, its mass is negligible. No evidence is found for a very cold (6-10 K) dust component. The temperature of the cold dust component is strongly influenced by the ratio of the star formation rate to the total dust mass. This implies, contrary to what is often assumed, that a significant fraction of even the emission from ∼20 K dust is powered by ongoing star formation, whether or not the dust itself is associated with star-forming clouds or 'cirrus'. There is statistical evidence of a free-free contribution to the 217 GHz flux densities of 20 per cent. We find a median dust-to-stellar mass ratio of 0.0046; and that this ratio is anticorrelated with galaxy mass. There is good correlation between dust mass and atomic gas mass (median M d /M H I = 0.022), suggesting that galaxies that have more dust (higher values of M d /M * ) have more interstellar medium in general. Our derived dust mass function implies a mean dust mass density of the local Universe (for dust within galaxies), of 7.0 ± 1.4 × 10 5 M Mpc −3 , significantly greater than that found in the most recent estimate using Herschel data.