Micron Survey Research Articles

A Spitzer Search for the Missing Supernovae in the Galactic Nuclei of ULIRGS

AbstractSupernova (SN) rates serve as an important probe of star formation models and initial mass functions, particularly at high redshifts due to the SN intrinsic luminosity. Ground-based optical surveys, however, typically discover nearly ten times fewer SNe than predicted, challenging our understanding of massive star formation and evolution. These results are generally attributed to the high dust extinction associated with the nuclei of star forming galaxies, such as Ultra Luminous InfraRed Galaxies (ULIRGs). Near-infrared surveys have been unsuccessful due to extinction values exceeding AV > 25 mag, and even on an 8-m AO system, subtraction algorithms used to find the SNe inevitably leave large residuals associated with the inner 2” of the galactic nucleus, which is where a majority of the SNe occur. A successful survey must be conducted at longer wavelengths and with a space-based telescope, which has stable seeing that reduces the necessity for any subtraction algorithms and, therefore, residuals. Here we present ongoing work from our 300 hour Spitzer 3.6 micron survey for dust-extinguished SNe in the nuclear regions of ULIRGs within 200 Mpc. The direct product of this study will be an improved understanding of the connection between the far-IR luminosity of ULIRGs and massive star formation.

A SCUBA-2 850-μm survey of protoplanetary discs in the σ Orionis cluster

We present the results from a large 850 micron survey of the sigma Orionis cluster using the SCUBA-2 camera on the James Clerk Maxwell Telescope. The 0.5-degree diameter circular region we surveyed contains 297 young stellar objects with an age estimated at about 3Myr. We detect 9 of these objects, 8 of which have infrared excesses from an inner disc. We also serendipitously detect 3 non-stellar sources at > 5sigma that are likely background submillimetre galaxies. The 9 detected stars have inferred disc masses ranging from 5 to about 17MJup, assuming similar dust properties as Taurus discs and an ISM gas-to-dust ratio of 100. There is a net positive signal toward the positions of the individually undetected infrared excess sources indicating a mean disc mass of 0.5 MJup . Stacking the emission toward those stars without infrared excesses constrains their mean disc mass to less than 0.3MJup, or an equivalent Earth mass in dust. The submillimetre luminosity distribution is significantly different from that in the younger Taurus region, indicating disc mass evolution as star forming regions age and the infrared excess fraction decreases. Submillimeter Array observations reveal CO emission toward 4 sources demonstrating that some, but probably not much, molecular gas remains in these relatively evolved discs. These observations provide new constraints on the dust and gas mass of protoplanetary discs during the giant planet building phase and provide a reference level for future studies of disc evolution.

AN ALMA SURVEY OF SUBMILLIMETER GALAXIES IN THE EXTENDED CHANDRA DEEP FIELD SOUTH: SOURCE CATALOG AND MULTIPLICITY

We present an Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 0 survey of 126 submillimeter sources from the LABOCA ECDFS Submillimeter Survey (LESS). Our 870 micron survey with ALMA (ALESS) has produced maps ~3X deeper and with a beam area ~200X smaller than the original LESS observations, doubling the current number of interferometrically-observed submillimeter sources. The high resolution of these maps allows us to resolve sources that were previously blended and accurately identify the origin of the submillimeter emission. We discuss the creation of the ALESS submillimeter galaxy (SMG) catalog, including the main sample of 99 SMGs and a supplementary sample of 32 SMGs. We find that at least 35% (possibly up to 50%) of the detected LABOCA sources have been resolved into multiple SMGs, and that the average number of SMGs per LESS source increases with LESS flux density. Using the (now precisely known) SMG positions, we empirically test the theoretical expectation for the uncertainty in the single-dish source positions. We also compare our catalog to the previously predicted radio/mid-infrared counterparts, finding that 45% of the ALESS SMGs were missed by this method. Our ~1.6" resolution allows us to measure a size of ~9 kpc X 5 kpc for the rest-frame ~300 um emission region in one resolved SMG, implying a star formation rate surface density of 80 M_sol yr^-1 kpc^-2, and we constrain the emission regions in the remaining SMGs to be <10 kpc. As the first statistically reliable survey of SMGs, this will provide the basis for an unbiased multiwavelength study of SMG properties.

The AKARI Deep Field-South: Spitzer 24- and 70-μm observations, catalogues and counts

The AKARI Deep Field South (ADF-S) is a ~12 sq. deg. region near the South Ecliptic Pole that has been observed with deep scans in the far-infrared by the AKARI satellite. As such it is becoming one of the key extragalactic survey fields. We here present complementary observations of the ADF-S conducted by the Spitzer Space Telescope at wavelengths of 24 and 70 micron. We extract source catalogs at each of these wavelengths reaching depths of ~ 0.2mJy at 24 micron and ~ 20mJy at 70 micron. We also apply an K-to-24 micron colour criterion to select objects with galaxy-like colours in the 24 micron survey. Completeness corrections as a function of flux density are derived for both catalogs by injecting artificial sources of known flux density into the maps, and we find that our surbveys are 50% complete at 0.26mJy and 24mJy at 24 and 70 micron respectively. We can thus produce number counts as a function of flux density for the ADF-S at 24 and 70 micron. These are combined with existing literature counts and compared to four different number count models derived from galaxy evolution models. One complicating factor for the ADF-S counts is the presence of a foreground galaxy cluster at z=0.04 in the field. We examine the ranges of flux densities to which this cluster might make a contribution to the counts and find hints that the 24 micron luminosity function of the cluster galaxies might be enhanced above that of field galaxies. Full catalogs for these ADF-S Spitzer surveys at 24 and 70 micron are made available as part of this paper.

A CATALOG OF MIPSGAL DISK AND RING SOURCES

We present a catalog of 416 extended, resolved, disk- and ring-like objects as detected in the MIPSGAL 24 micron survey of the Galactic plane. This catalog is the result of a search in the MIPSGAL image data for generally circularly symmetric, extended "bubbles" without prior knowledge or expectation of their physical nature. Most of the objects have no extended counterpart at 8 or 70 micron, with less than 20% detections at each wavelength. For the 54 objects with central point sources, the sources are nearly always seen in all IRAC bands. About 70 objects (16%) have been previously identified, with another 35 listed as IRAS sources. Among the identified objects, those with central sources are mostly listed as emission-line stars, but with other source types including supernova remnants, luminous blue variables, and planetary nebulae. The 57 identified objects (of 362) without central sources are nearly all PNe (~90%).which suggests that a large fraction of the 300+ unidentified objects in this category are also PNe. These identifications suggest that this is primarily a catalog of evolved stars. Also included in the catalog are two filamentary objects that are almost certainly SNRs, and ten unusual compact extended objects discovered in the search. Two of these show remarkable spiral structure at both 8 and 24 micron. These are likely background galaxies previously hidden by the intervening Galactic plane.

An infrared-radio simulation of the extragalactic sky: from the Square Kilometre Array toHerschel

To exploit synergies between the Herschel Space Observatory and next generation radio facilities, we have extended the semi-empirical extragalactic radio continuum simulation of Wilman et al. (2008) to the mid- and far-infrared. Here we describe the assignment of infrared spectral energy distributions (SEDs) to the star-forming galaxies and active galactic nuclei, using Spitzer 24, 70 and 160 micron and SCUBA 850 micron survey results as the main constraints. Star-forming galaxies dominate the source counts, and a model in which their far-infrared-radio correlation and infrared SED assignment procedure are invariant with redshift underpredicts the observed 24 and 70 micron source counts. The 70 micron deficit can be eliminated if the star-forming galaxies undergo stronger luminosity evolution than originally assumed for the radio simulation, a requirement which may be partially ascribed to known non-linearity in the far-infrared--radio correlation at low luminosity if it evolves with redshift. At 24 micron, the shortfall is reduced if the star-forming galaxies develop SEDs with cooler dust and correspondingly stronger Polycyclic Aromatic Hydrocarbon (PAH) emission features with increasing redshift at a given far-infrared luminosity, but this trend may reverse at z>1 in order not to overproduce the sub-mm source counts. The resulting model compares favourably with recent BLAST results and we have extended the simulation database to aid the interpretation of Herschel surveys. Such comparisons may also facilitate further model refinement and revised predictions for the SKA and its precursors.

THE BLAST SURVEY OF THE VELA MOLECULAR CLOUD: PHYSICAL PROPERTIES OF THE DENSE CORES IN VELA-D

The Balloon-borne Large-Aperture Submillimeter Telescope (BLAST) carried out a 250, 350 and 500 micron survey of the galactic plane encompassing the Vela Molecular Ridge, with the primary goal of identifying the coldest dense cores possibly associated with the earliest stages of star formation. Here we present the results from observations of the Vela-D region, covering about 4 square degrees, in which we find 141 BLAST cores. We exploit existing data taken with the Spitzer MIPS, IRAC and SEST-SIMBA instruments to constrain their (single-temperature) spectral energy distributions, assuming a dust emissivity index beta = 2.0. This combination of data allows us to determine the temperature, luminosity and mass of each BLAST core, and also enables us to separate starless from proto-stellar sources. We also analyze the effects that the uncertainties on the derived physical parameters of the individual sources have on the overall physical properties of starless and proto-stellar cores, and we find that there appear to be a smooth transition from the pre- to the proto-stellar phase. In particular, for proto-stellar cores we find a correlation between the MIPS24 flux, associated with the central protostar, and the temperature of the dust envelope. We also find that the core mass function of the Vela-D cores has a slope consistent with other similar (sub)millimeter surveys.

THE LARGE APEX BOLOMETER CAMERA SURVEY OF THE EXTENDED CHANDRA DEEP FIELD SOUTH

We present a sensitive 870 micron survey of the Extended Chandra Deep Field South (ECDFS) using LABOCA on the APEX telescope. The LABOCA ECDFS Submillimetre Survey (LESS) covers the full 30' x 30' field size of the ECDFS and has a uniform noise level of 1.2 mJy/beam. LESS is thus the largest contiguous deep submillimetre survey undertaken to date. The noise properties of our map show clear evidence that we are beginning to be affected by confusion noise. We present a catalog of 126 SMGs detected with a significance level above 3.7 sigma. The ECDFS exhibits a deficit of bright SMGs relative to previously studied blank fields but not of normal star-forming galaxies that dominate the extragalactic background light (EBL). This is in line with the underdensities observed for optically defined high redshift source populations in the ECDFS (BzKs, DRGs,optically bright AGN and massive K-band selected galaxies). The differential source counts in the full field are well described by a power law with a slope of alpha=-3.2, comparable to the results from other fields. We show that the shape of the source counts is not uniform across the field. The integrated 870 micron flux densities of our source-count models account for >65% of the estimated EBL from COBE measurements. We have investigated the clustering of SMGs in the ECDFS by means of a two-point correlation function and find evidence for strong clustering on angular scales <1'. Assuming a power law dependence for the correlation function and a typical redshift distribution for the SMGs we derive a spatial correlation length of r_0=13+/-6 h^-1 Mpc.

Large‐Area Mapping at 850 μm. V. Analysis of the Clump Distribution in the Orion A South Molecular Cloud

We present results from a 2300 arcmin^2 survey of the Orion A molecular cloud at 450 and 850 micron using the Submillimetre Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope. The region mapped lies directly south of the OMC1 cloud core and includes OMC4, OMC5, HH1/2, HH34, and L1641N. We identify 71 independent clumps in the 850 micron map and compute size, flux, and degree of central concentration in each. Comparison with isothermal, pressure-confined, self-gravitating Bonnor-Ebert spheres implies that the clumps have internal temperatures T_d ~ 22 +/- K and surface pressures log (k^-1 P cm^-3 K) = 6.0 +/- 0.2. The clump masses span the range 0.3 - 22 Msun assuming a dust temperature T_d ~ 20 K and a dust emissivity kappa_850 = 0.02 cm^2 g^-1. The distribution of clump masses is well characterized by a power-law N(M) propto M^-alpha with alpha = 2.0 +/- 0.5 for M > 3.0 Msun, indicating a clump mass function steeper than the stellar Initial Mass Function. Significant incompleteness makes determination of the slope at lower masses difficult. A comparison of the submillimeter emission map with an H_2 2.122 micron survey of the same region is performed. Several new Class 0 sources are revealed and a correlation is found between both the column density and degree of concentration of the submillimeter sources and the likelihood of coincident H_2 shock emission.

The milliJansky 12- m population: first follow-up

We present the first results of our followup programme of optical imaging and spectroscopy of a deep 12 micron survey conducted with the ISO satellite (Clements et al. 1999). We find that the objects are typically of fairly low redshift (z ~ 0.1-0.2), but with a tail that extends to high redshifts. The highest redshift object is a previously unknown quasar at z=1.2. The sample of objects for which spectroscopy has been obtained forms a complete subsample of the original survey with an R band magnitude limit of 19.6. We are thus able to use accessible volume methods to determine the luminosity function. We find that the luminosity function is close to the low redshift 12 micron luminosity function determined by IRAS (Fang et al., 1998; Rush et al., 1993), but with a possible excess at the highest luminosities, which also correspond to the highest redshifts. This excess is compatible with the rapid luminosity evolution of L ~ (1+z)^{4.5} claimed by Xu (2000) and suggested by Elbaz (1999) on the basis of number counts. These conclusions remain tentative because of small number statistics at the highest redshifts. Almost all of the galaxies in this survey are emission line objects. We use the spectra to determine emission line diagnostics for the underlying ionisation source. We find that the majority of objects have HII region-like spectra (roughly 2/3) but there is a significant fraction (about 1/3) that contain an AGN. This confirms suspicions that deep mid-IR surveys will be a powerful way to find obscured AGN. Part of the survey area has been imaged deeply by the INT Wide Field Camera. Nearly all 12 micron sources in this area have good optical identifications. The prospects are thus good for obtaining complete spectroscopy.

Galaxy Evolution in the Optical and Submillimeter

I review the emerging picture of galaxy formation and evolution that is coming from observations in the optical waveband and in the submillimeter waveband. In the former I look at the work of several groups but in the latter I focus on the results from the Canada-UK Deep Submillimeter Survey (CUDSS), an 850 micron survey of about 100 square arcmin of sky carried out with SCUBA to a limiting flux of 3 mJy. I discuss what we do and do not know about the sources responsible for emitting a significant fraction of the extragalactic background at 850 microns.

Spatial correlation between Halpha emission and infrared cirrus.

Cross-correlation of the DIRBE 100 micron survey with previously published H-alpha maps tests correlations between far-infrared dust and the warm ionized interstellar medium in different regions of the sky. A 10 x 12 deg patch at Galactic latitude b = -21 shows a correlation slope a_0 = 0.85 +/- 0.44 Rayleighs / MJy sr significant at 97% confidence. A set of H-alpha images over the north celestial polar cap yields a weaker correlation slope a_0 = 0.34 +/- 0.33 Rayleighs / MJy sr. Combined with observations from microwave anisotropy experiments, the data show roughly similar correlations on angular scales 0.7 deg to 90 deg. Microwave experiments may observe more emission per unit dust emission than are traced by the same structures observed in H-alpha.

The frequency of circumstellar envelopes among TMSS stars

We investigated the distribution of Neugebauer and Leighton’s two micron survey (TMSS) stars on the {K- [12]; [12] - [25]} and {[12] - [25]; [25] - [60]} planes. The frequency of circumstellar emission objects among B-K type stars is less than 5% while it reaches about 20% at M, 80% at stars with unknown spectra and 90% at carbon stars.

Circumstellar shells resolved in the IRAS survey data. I - Data processing procedure, results, and confidence tests

We have examined the IRAS 60 and 100 micron survey data covering 512 evolved stars and young planetary nebulae for evidence of spatially resolved structure. A simple model, consisting of a central unresolved source surrounded by a resolved isothermal shell, was fitted to the data for each star. Seventy-six stars were found to be resolved in the 60 micron data. Tests have been performed to verify that the extended structure seen is not an artifact of the data-processing algorithm.

A 2.2 micron survey in the L1630 molecular cloud

A 2.2 micron survey of a significant portion of the L1630 molecular cloud was carried out using the NOAO infrared array camera on the Kitt Peak 1.3 m telescope. This survey is estimated to be complete to 13th magnitude at K, which corresponds to a main-sequence star of about 0.6 solar mass. Therefore this survey has provided a sensitive census of the young stellar objects within this molecular cloud. As a result, 912 sources having m(K) less than 13.0 have been detected. It is estimated that 50 percent of these sources are associated with the molecular cloud. These sources are not distributed uniformly throughout the surveyed region but rather appear grouped or clustered. In fact, four embedded infrared clusters were identified. These clusters contain at least 58 percent but possibly as much as 96 percent of the total number of sources associated with this molecular cloud suggesting that the dominant mode of star formation in this region is in clusters.

Studies of IRAS sources at high galactic latitudes – I. Source counts at $|b|\gt60^\circ$ and evidence for a north–south anisotropy of cosmological significance

A study of the IRAS sky at b with an absolute value greater than 60 deg is conducted. Source counts at 12, 25, 60 and 100 microns are presented, and it is shown that emission from interstellar dust at 100 microns is localized to a few small areas of tathe galactic polar caps. At 12 and 25 microns, the sky is dominated by stars; at 60 and 100 microns, by galaxies. Comparison with the minisurvey source counts indicates the 12and 25-micron source denstiy is lower at the present latitude than at a latitude whereby the absolute value of b equals 10-40 deg. Due to the greatly reduced effects of emission from interstellar dust, the 100 micron survey reaches a factor 1.6 deeper in flux at the present latitude than the minisurvey. An anisotropy significant at the 4-sigma level was found between the north and south galactic polar caps at 60 and 100 microns, after exclusion of the Virgo cluster and of the few remaining areas significantly affected by interstellar-dust emission. It is suggested that this anisotropy represents a cosmologically significant anisotropy in the galaxy distribution. The scale of associated inhomogeneity is of the order of at least 100(50/H)Mpc.

Interactions between pre-main-sequence objects and molecular clouds. I - Elias 1-12

view Abstract Citations (40) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Interactions between pre-main-sequence objects and molecular clouds. I. Elias 1-12. Levreault, R. M. Abstract Elias 1-12 is a heavily obscured star in the IC5146 dark cloud. It was discovered during a 2 micron survey by Elias (1978). The photometric history of the star and its 2 micron spectrum led to a probable identification as only the fourth known FU Orionis star. The FU Orionis phenomenon consists of a T Tauri star undergoing an outburst of 5-6 mag. It was decided to include Elias 1-12 in a survey of CO emission-line profiles toward pre-main-sequence objects. In the present investigation, 'CO' refers to (C-12)(O16). On the basis of the obtained results, it is concluded that the FU Orionis star Elias 1-12 is surrounded by an area of perturbed molecular gas. This gas extends up to 0.3 pc from the star, has a total mass of 1.2 solar masses, and a kinetic temperature of 7-15 K. The observed characteristics can be explained on the basis of a stellar wind driven shell. Publication: The Astrophysical Journal Pub Date: February 1983 DOI: 10.1086/160731 Bibcode: 1983ApJ...265..855L Keywords: Carbon Monoxide; Molecular Clouds; Molecular Spectra; Stellar Envelopes; Stellar Mass Ejection; T Tauri Stars; Abundance; Gas Density; Gas Temperature; Interstellar Gas; Shock Heating; Spectral Energy Distribution; Spectral Line Width; Stellar Evolution; Stellar Spectra; Stellar Winds; Astrophysics full text sources ADS | data products SIMBAD (4) Related Materials (1) Part 2: 1984ApJ...277..634L

Comparison of Colour Curves of Mira Stars of Spectrum M and S

Colour variations for Mira stars of spectrum Me and Se are deduced from the two micron survey of Neugebauer and Leighton and concurrent visual observations of the same stars.The colours change cyclically during the periodic change of brightness. Colour is a function of maximal spectrum and also of period. Mira stars of class Se are bluer than those of Me of similar period.

Two Infrared Sources in Nebulae

IN a systematic survey of the Caltech infrared catalogue (IRC)1, 210 of the 5612 listed sources have been examined optically using the prints of the National Geographic Society–Palomar Observatory sky survey. Several criteria were adopted in the selection of sources for optical examination. Objects were first selected for which no previous identification was listed on the basis of comparison with star catalogues, and which further were very red as indicated by their I (0.84 µm) minus K (2.2 µm) colour index. The reddest sources among these have (I − K) ≥ 6m.00 and all such cases were examined, whereas for the moderately red objects ((I − K) ≳ 4m.00) only sources at high galactic latitude (|bII| ≥ 40°), or lying in the +40° declination zone of the two micron survey, or located near stellar rings2, were inspected. During the work, a number of infrared stars of (I − K) ≳ 4m.00 but catalogued as belonging to spectral class B were also located. Examination of the sky survey prints revealed that the infrared object, in sixteen cases out of twenty investigated, was a fainter, very red star lying near the class B star in question. Some further named stars in the catalogue whose right ascension and declination offsets relative to the infrared source exceeded ∼ 6 s and/or ∼1′.2 were also examined, and again in nine cases out of fourteen a more satisfactory identification was made. On the basis of this admittedly small sample of stars with large offsets, it is suggested that such errors of identification may number about 100 stars throughout the catalogue, or about 2 per cent of the total.