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Recent observations support the hypothesis that a large fraction of "short-hard" gamma-ray bursts (SHBs) are associated with the inspiral and merger of compact binaries. Since gravitational-wave (GW) measurements of well-localized inspiraling binaries can measure absolute source distances, simultaneous observation of a binary's GWs and SHB would allow us to directly and independently determine both the binary's luminosity distance and its redshift. Such a "standard siren" (the GW analog of a standard candle) would provide an excellent probe of the nearby (z [?] 0.3) universe's expansion, independent of the cosmological distance ladder, thereby complementing other standard candles. Previous work explored this idea using a simplified formalism to study measurement by advanced GW detector networks, incorporating a high signal-to-noise ratio limit to describe the probability distribution for measured parameters. In this paper, we eliminate this simplification, constructing distributions with a Markov Chain Monte Carlo technique. We assume that each SHB observation gives source sky position and time of coalescence, and we take non-spinning binary neutron star and black hole-neutron star coalescences as plausible SHB progenitors. We examine how well parameters (particularly distance) can be measured from GW observations of SHBs by a range of ground-based detector networks. We find that earlier estimates overstate how well distances can be measured, even at fairly large signal-to-noise ratio. The fundamental limitation to determining distance proves to be a degeneracy between distance and source inclination. Overcoming this limitation requires that we either break this degeneracy, or measure enough sources to broadly sample the inclination distribution.

We show that the expansion of ejecta in Tycho's supernova remnant (SNR) is consistent with a spherically symmetric shell, based on Suzaku measurements of the Doppler broadened X-ray emission lines. All of the strong Ka line emissions show broader widths at the center than at the rim, while the centroid energies are constant across the remnant (except for Ca). This is the pattern expected for Doppler broadening due to expansion of the SNR ejecta in a spherical shell. To determine the expansion velocities of the ejecta, we applied a model for each emission-line feature having two Gaussian components separately representing red- and blueshifted gas, and inferred the Doppler velocity difference between these two components directly from the fitted centroid energy difference. Taking into account the effect of projecting a three-dimensional shell to the plane of the detector, we derived average spherical expansion velocities independently for the Ka emission of Si, S, Ar, and Fe, and Kb of Si. We found that the expansion velocities of Si, S, and Ar ejecta of 4700 +- 100 km s-1 are distinctly higher than that obtained from Fe Ka emission, 4000 +- 300 km s-1, which is consistent with segregation of the Fe in the inner ejecta. Combining the observed ejecta velocities with the ejecta proper-motion measurements by Chandra, we derived a distance to Tycho's SNR of 4 +- 1 kpc.

We present optical and X-ray properties for the first confirmed galaxy cluster sample selected by the Sunyaev-Zel'dovich effect (SZE) from 148 GHz maps over 455 deg2 of sky made with the Atacama Cosmology Telescope (ACT). These maps, coupled with multi-band imaging on 4 m class optical telescopes, have yielded a sample of 23 galaxy clusters with redshifts between 0.118 and 1.066. Of these 23 clusters, 10 are newly discovered. The selection of this sample is approximately mass limited and essentially independent of redshift. We provide optical positions, images, redshifts, and X-ray fluxes and luminosities for the full sample, and X-ray temperatures of an important subset. The mass limit of the full sample is around 8.0 x 1014 M , with a number distribution that peaks around a redshift of 0.4. For the 10 highest significance SZE-selected cluster candidates, all of which are optically confirmed, the mass threshold is 1 x 1015 M and the redshift range is 0.167-1.066. Archival observations from Chandra, XMM-Newton, and ROSAT provide X-ray luminosities and temperatures that are broadly consistent with this mass threshold. Our optical follow-up procedure also allowed us to assess the purity of the ACT cluster sample. Eighty (one hundred) percent of the 148 GHz candidates with signal-to-noise ratios greater than 5.1 (5.7) are confirmed as massive clusters. The reported sample represents one of the largest SZE-selected sample of massive clusters over all redshifts within a cosmologically significant survey volume, which will enable cosmological studies as well as future studies on the evolution, morphology, and stellar populations in the most massive clusters in the universe.

We have carried out the first general submillimeter analysis of the field toward GRSMC 45.46+0.05, a massive star-forming region in Aquila. The deconvolved 6 deg2 (3deg x 2deg) maps provided by BLAST in 2005 at 250, 350, and 500 mm were used to perform a preliminary characterization of the clump population previously investigated in the infrared, radio, and molecular maps. Interferometric CORNISH data at 4.8 GHz have also been used to characterize the Ultracompact H II regions (UCHIIRs) within the main clumps. By means of the BLAST maps, we have produced an initial census of the submillimeter structures that will be observed by Herschel, several of which are known Infrared Dark Clouds. Our spectral energy distributions of the main clumps in the field, located at [?]7 kpc, reveal an active population with temperatures of T[?] 35-40 K and masses of [?]103 M for a dust emissivity index b = 1.5. The clump evolutionary stages range from evolved sources, with extended H II regions and prominent IR stellar population, to massive young stellar objects, prior to the formation of an UCHIIR. The CORNISH data have revealed the details of the stellar content and structure of the UCHIIRs. In most cases, the ionizing stars corresponding to the brightest radio detections are capable of accounting for the clump bolometric luminosity, in most cases powered by embedded OB stellar clusters.

Samples returned from comet 81P/Wild 2 by the Stardust mission confirm that substantial quantities of crystalline silicates were incorporated into the comet at the time of its formation. We investigate the constraints that this observation places upon protoplanetary disk physics, under the assumption that outward transport of particles processed at high temperatures occurs via a combination of advection and turbulent diffusion in an evolving disk. We also look for possible constraints on the formation locations of such particles. Our results are based upon one-dimensional disk models that evolve with time under the action of viscosity and photoevaporative mass loss, and track solid transport using an ensemble of individual particle trajectories. We find that two broad classes of the disk model are consistent with the Stardust findings. One class of models features a high particle diffusivity (a Schmidt number, Sc < 1), which suffices to diffuse particles up to 20 mm in size outward against the mean gas flow. For Sc [?] 1 such models are unlikely to be viable and significant outward transport appears to require that the particles of interest settle into a midplane layer that experiences an outward gas flow. In either class of models, the mass of inner disk material that reaches the outer disk is a strong function of the initial compactness of the disk. Hence, models of grain transport within steady-state disks underestimate the efficiency of outward transport. Neither model results in sustained outward transport of very large particles exceeding a millimeter in size. We show that in most circumstances, the transport efficiency falls off rapidly with time. Hence, high-temperature material must be rapidly incorporated into icy bodies to avoid fallback to small radii. We suggest that significant radial transport may only occur during the initial phase of rapid disk evolution. It may also vary substantially between disks depending upon their initial mass distributions. We discuss how our model may inform recent Spitzer observations of crystalline silicates in T Tauri star-disk systems.

We study the outer-shock structure of the oxygen-rich supernova remnant G292.0+1.8 using a deep observation with the Chandra X-ray Observatory. We measure radial variations of the electron temperature and emission measure that we identify as the outer shock propagating into a medium with a radially decreasing density profile. The inferred ambient density structure is consistent with models for the circumstellar wind of a massive progenitor star rather than for a uniform interstellar medium. The estimated wind density (n H = 0.1-0.3 cm-3) at the current outer radius ([?] 7.7 pc) of the remnant is consistent with a slow wind from a red supergiant (RSG) star. The total mass of the wind is estimated to be [?]15-40 M (depending on the estimated density range), assuming that the wind extended down to near the surface of the progenitor. The overall kinematics of G292.0+1.8 are consistent with the remnant expanding through the RSG wind.

Using our deep [?]120 ks Chandra observation, we report on the results from our spatially resolved X-ray spectral analysis of the "oxygen-rich" supernova remnant (SNR) 0540-69.3 in the Large Magellanic Cloud. We conclusively establish the nonthermal nature of the "arcs" in the east and west boundaries of the SNR, which confirms the cosmic-ray electron acceleration in the supernova shock (B [?] 20-140 mG). We report tentative evidence for Fe overabundance in the southern region close to the outer boundary of the SNR. While such a detection would be intriguing, the existence of Fe ejecta is not conclusive with the current data because of poor photon statistics and limited plasma models. If it is verified using deeper X-ray observations and improved plasma models, the presence of Fe ejecta, which was produced in the core of the supernova, near the SNR's outer boundary would provide an intriguing opportunity to study the explosive nucleosynthesis and the ejecta mixing in this young core-collapse SNR. There is no evidence of X-ray counterparts for the optical O-rich ejecta in the central regions of the SNR.

We present X-ray proper-motion measurements of the forward shock and reverse-shocked ejecta in Tycho's supernova remnant, based on three sets of archival Chandra data taken in 2000, 2003, and 2007. We find that the proper motion of the edge of the remnant (i.e., the forward shock and protruding ejecta knots) varies from 0.''20 yr-1 (expansion index m = 0.33, where R = tm ) to 0.''40 yr-1 (m = 0.65) with azimuthal angle in 2000-2007 measurements, and 0.''14 yr-1 (m = 0.26) to 0.''40 yr-1 (m = 0.65) in 2003-2007 measurements. The azimuthal variation of the proper motion and the average expansion index of [?]0.5 are consistent with those derived from radio observations. We also find proper motion and expansion index of the reverse-shocked ejecta to be 0.''21-0.''31 yr-1 and 0.43-0.64, respectively. From a comparison of the measured m-value with Type Ia supernova evolutionary models, we find a pre-shock ambient density around the remnant of [?]0.2 cm-3.

We report multi-wavelength power spectra of diffuse Galactic dust emission from Balloon-borne Large Aperture Submillimeter Telescope observations at 250, 350, and 500 mm in Galactic plane fields in Cygnus X and Aquila. These submillimeter power spectra statistically quantify the self-similar structure observable over a broad range of scales and can be used to assess the cirrus noise which limits the detection of faint point sources. The advent of submillimeter surveys with the Herschel Space Observatory makes the wavelength dependence a matter of interest. We show that the observed relative amplitudes of the power spectra can be related through a spectral energy distribution (SED). Fitting a simple modified black body to this SED, we find the dust temperature in Cygnus X to be 19.8 +- 1.5 K and in the Aquila region 16.8 +- 0.8 K. Our empirical estimates provide important new insight into the substantial cirrus noise that will be encountered in forthcoming observations.

The Balloon-borne Large-Aperture Submillimeter Telescope (BLAST) carried out a 250, 350, and 500 mm 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 deg2, 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 b = 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 protostellar 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 protostellar cores, and we find that there appear to be a smooth transition from the pre- to the protostellar phase. In particular, for protostellar 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.

Over the course of two flights, the Balloon-borne Large Aperture Submillimeter Telescope (BLAST) made resolved maps of seven nearby (<25 Mpc) galaxies at 250, 350, and 500 mm. During its 2005 June flight from Sweden, BLAST observed a single nearby galaxy, NGC 4565. During the 2006 December flight from Antarctica, BLAST observed the nearby galaxies NGC 1097, NGC 1291, NGC 1365, NGC 1512, NGC 1566, and NGC 1808. We fit physical dust models to a combination of BLAST observations and other available data for the galaxies observed by Spitzer. We fit a modified blackbody to the remaining galaxies to obtain total dust mass and mean dust temperature. For the four galaxies with Spitzer data, we also produce maps and radial profiles of dust column density and temperature. We measure the fraction of BLAST detected flux originating from the central cores of these galaxies and use this to calculate a "core fraction," an upper limit on the "active galactic nucleus fraction" of these galaxies. We also find our resolved observations of these galaxies give a dust mass estimate 5-19 times larger than an unresolved observation would predict. Finally, we are able to use these data to derive a value for the dust mass absorption coefficient of k = 0.29 +- 0.03 m2 kg-1 at 250 mm. This study is an introduction to future higher-resolution and higher-sensitivity studies to be conducted by Herschel and SCUBA-2.

We present first results from an unbiased 50 deg2 submillimeter Galactic survey at 250, 350, and 500 mm from the 2006 flight of the Balloon-borne Large Aperture Submillimeter Telescope. The map has resolution ranging from 36'' to 60'' in the three submillimeter bands spanning the thermal emission peak of cold starless cores. We determine the temperature, luminosity, and mass of more than 1000 compact sources in a range of evolutionary stages and an unbiased statistical characterization of the population. From comparison with C18O data, we find the dust opacity per gas mass, kr= 0.16 cm2 g-1 at 250 mm, for cold clumps. We find that 2% of the mass of the molecular gas over this diverse region is in cores colder than 14 K, and that the mass function for these cold cores is consistent with a power law with index a = -3.22 +- 0.14 over the mass range 14 M < M < 80 M . Additionally, we infer a mass-dependent cold core lifetime of tc (M) = 4 x 106(M/20 M )-0.9 yr--longer than what has been found in previous surveys of either low or high-mass cores, and significantly longer than free fall or likely turbulent decay times. This implies some form of non-thermal support for cold cores during this early stage of star formation.

The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) has recently surveyed [?]8.7 deg2 centered on Great Observatories Origins Deep Survey-South at 250, 350, and 500 mm. In Dye et al., we presented the catalog of sources detected at 5s in at least one band in this field and the probable counterparts to these sources in other wavebands. In this paper, we present the results of a redshift survey in which we succeeded in measuring redshifts for 82 of these counterparts. The spectra show that the BLAST counterparts are mostly star-forming galaxies but not extreme ones when compared to those found in the Sloan Digital Sky Survey. Roughly one quarter of the BLAST counterparts contain an active nucleus. We have used the spectroscopic redshifts to carry out a test of the ability of photometric redshift methods to estimate the redshifts of dusty galaxies, showing that the standard methods work well even when a galaxy contains a large amount of dust. We have also investigated the cases where there are two possible counterparts to the BLAST source, finding that in at least half of these there is evidence that the two galaxies are physically associated, either because they are interacting or because they are in the same large-scale structure. Finally, we have made the first direct measurements of the luminosity function in the three BLAST bands. We find strong evolution out to z = 1, in the sense that there is a large increase in the space density of the most luminous galaxies. We have also investigated the evolution of the dust-mass function, finding similar strong evolution in the space density of the galaxies with the largest dust masses, showing that the luminosity evolution seen in many wavebands is associated with an increase in the reservoir of interstellar matter in galaxies.

We detect correlations in the cosmic far-infrared background due to the clustering of star-forming galaxies in observations made with the Balloon-borne Large Aperture Submillimeter Telescope, at 250, 350, and 500 mm. We perform jackknife and other tests to confirm the reality of the signal. The measured correlations are well fitted by a power law over scales of 5'-25', with DI/I = 15.1% +- 1.7%. We adopt a specific model for submillimeter sources in which the contribution to clustering comes from sources in the redshift ranges 1.3 [?] z [?] 2.2, 1.5 [?] z [?] 2.7, and 1.7 [?] z [?] 3.2, at 250, 350, and 500 mm, respectively. With these distributions, our measurement of the power spectrum, P(k th), corresponds to linear bias parameters, b = 3.8 +- 0.6, 3.9 +- 0.6, and 4.4 +- 0.7, respectively. We further interpret the results in terms of the halo model, and find that at the smaller scales, the simplest halo model fails to fit our results. One way to improve the fit is to increase the radius at which dark matter halos are artificially truncated in the model, which is equivalent to having some star-forming galaxies at z [?] 1 located in the outskirts of groups and clusters. In the context of this model, we find a minimum halo mass required to host a galaxy is log(M min/M ) = 11.5+0.4 -0.1, and we derive effective biases b eff = 2.2 +- 0.2, 2.4 +- 0.2, and 2.6 +- 0.2, and effective masses $\mathrm{log}(M_{\mathrm{\rm eff}}/M_{\odot }) = 12.9 \pm 0.3$, 12.8 +- 0.2, and 12.7 +- 0.2, at 250, 350 and 500 mm, corresponding to spatial correlation lengths of r 0 = 4.9, 5.0, and $5.2 \pm 0.7 h^{-1} \rm Mpc$, respectively. Finally, we discuss implications for clustering measurement strategies with Herschel and Planck.

We describe the application of a statistical method to estimate submillimeter galaxy number counts from confusion-limited observations by the Balloon-borne Large Aperture Submillimeter Telescope (BLAST). Our method is based on a maximum likelihood fit to the pixel histogram, sometimes called "P(D)," an approach which has been used before to probe faint counts, the difference being that here we advocate its use even for sources with relatively high signal-to-noise ratios. This method has an advantage over standard techniques of source extraction in providing an unbiased estimate of the counts from the bright end down to flux densities well below the confusion limit. We specifically analyze BLAST observations of a roughly 10 deg2 map centered on the Great Observatories Origins Deep Survey South field. We provide estimates of number counts at the three BLAST wavelengths 250, 350, and 500 mm; instead of counting sources in flux bins we estimate the counts at several flux density nodes connected with power laws. We observe a generally very steep slope for the counts of about -3.7 at 250 mm, and -4.5 at 350 and 500 mm, over the range [?]0.02-0.5 Jy, breaking to a shallower slope below about 0.015 Jy at all three wavelengths. We also describe how to estimate the uncertainties and correlations in this method so that the results can be used for model-fitting. This method should be well suited for analysis of data from the Herschel satellite.

We directly measure redshift evolution in the mean physical properties (far-infrared luminosity, temperature, and mass) of the galaxies that produce the cosmic infrared background (CIB), using measurements from the Balloon-borne Large Aperture Submillimeter Telescope (BLAST), and Spitzer which constrain the CIB emission peak. This sample is known to produce a surface brightness in the BLAST bands consistent with the full CIB, and photometric redshifts are identified for all of the objects. We find that most of the 70 mm background is generated at z [?] 1 and the 500 mm background generated at z [?] 1. A significant growth is observed in the mean luminosity from [?]109-1012 L , and in the mean temperature by 10 K, from redshifts 0 < z < 3. However, there is only weak positive evolution in the comoving dust mass in these galaxies across the same redshift range. We also measure the evolution of the far-infrared luminosity density, and the star formation rate history for these objects, finding good agreement with other infrared studies up to z [?] 1, exceeding the contribution attributed to optically selected galaxies.

The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) has made 1 deg2, deep, confusion-limited maps at three different bands, centered on the Great Observatories Origins Deep Survey South Field. By calculating the covariance of these maps with catalogs of 24 mm sources from the Far-Infrared Deep Extragalactic Legacy Survey, we have determined that the total submillimeter intensities are 8.60 +- 0.59, 4.93 +- 0.34, and 2.27 +- 0.20 nW m-2 sr-1 at 250, 350, and 500 mm, respectively. These numbers are more precise than previous estimates of the cosmic infrared background (CIB) and are consistent with 24 mm-selected galaxies generating the full intensity of the CIB. We find that the fraction of the CIB that originates from sources at z [?] 1.2 increases with wavelength, with 60% from high-redshift sources at 500 mm. At all BLAST wavelengths, the relative intensity of high-z sources is higher for 24 mm-faint sources than that for 24 mm-bright sources. Galaxies identified as active galactic nuclei (AGNs) by their Infrared Array Camera colors are 1.6-2.6 times brighter than the average population at 250-500 mm, consistent with what is found for X-ray-selected AGNs. BzK-selected galaxies are found to be moderately brighter than typical 24 mm-selected galaxies in the BLAST bands. These data provide high-precision constraints for models of the evolution of the number density and intensity of star-forming galaxies at high redshift.

The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) operated successfully during a 250 hr flight over Antarctica in 2006 December (BLAST06). As part of the calibration and pointing procedures, the red hypergiant star VY CMa was observed and used as the primary calibrator. Details of the overall BLAST06 calibration procedure are discussed. The 1s uncertainty on the absolute calibration is accurate to 9.5%, 8.7%, and 9.2% at the 250, 350, and 500 mm bands, respectively. The errors are highly correlated between bands resulting in much lower errors for the derived shape of the 250-500 mm continuum. The overall pointing error is < 5'' rms for the 36'', 42'', and 60'' beams. The performance of optics and pointing systems is discussed.

We present arcsecond-resolution Submillimeter Array (SMA) polarimetric observations of the 880 mm continuum emission from the protoplanetary disks around two nearby stars, HD 163296 and TW Hydrae. Although previous observations and theoretical work have suggested that a 2%-3% polarization fraction should be common for the millimeter continuum emission from such disks, we detect no polarized continuum emission above a 3s upper limit of 7 mJy in each arcsecond-scale beam, or <1% in integrated continuum emission. We compare the SMA upper limits with the predictions from the exploratory Cho & Lazarian model of polarized emission from T Tauri disks threaded by toroidal magnetic fields, and rule out their fiducial model at the [?]10s level. We explore some potential causes for this discrepancy, focusing on model parameters that describe the shape, magnetic field alignment, and size distribution of grains in the disk. We also investigate related effects like the magnetic field strength and geometry, scattering off of large grains, and the efficiency of grain alignment, including recent advances in grain alignment theory, which are not considered in the fiducial model. We discuss the impact each parameter would have on the data and determine that the suppression of polarized emission plausibly arises from rounding of large grains, reduced efficiency of grain alignment with the magnetic field, and/or some degree of magnetic field tangling (perhaps due to turbulence). A poloidal magnetic field geometry could also reduce the polarization signal, particularly for a face-on viewing geometry like the TW Hya disk. The data provided here offer the most stringent limits to-date on the polarized millimeter-wavelength emission from disks around young stars.

We present results from a continuing interferometric survey of high-redshift submillimeter galaxies (SMGs) with the Submillimeter Array, including high-resolution (beam size [?]2 arcsec) imaging of eight additional AzTEC 1.1 mm selected sources in the COSMOS field, for which we obtain six reliable (peak signal-to-noise ratio (S/N) >5 or peak S/N >4 with multiwavelength counterparts within the beam) and two moderate significance (peak S/N >4) detections. When combined with previous detections, this yields an unbiased sample of millimeter-selected SMGs with complete interferometric follow up. With this sample in hand, we (1) empirically confirm the radio-submillimeter association, (2) examine the submillimeter morphology--including the nature of SMGs with multiple radio counterparts and constraints on the physical scale of the far infrared--of the sample, and (3) find additional evidence for a population of extremely luminous, radio-dim SMGs that peaks at higher redshift than previous, radio-selected samples. In particular, the presence of such a population of high-redshift sources has important consequences for models of galaxy formation--which struggle to account for such objects even under liberal assumptions--and dust production models given the limited time since the big bang.

We present the 250, 350, and 500 mm detection of bright submillimeter emission in the direction of the Bullet Cluster measured by the Balloon-borne Large-Aperture Submillimeter Telescope (BLAST). The 500 mm centroid is coincident with an AzTEC 1.1 mm point-source detection at a position close to the peak lensing magnification produced by the cluster. However, the 250 mm and 350 mm centroids are elongated and shifted toward the south with a differential shift between bands that cannot be explained by pointing uncertainties. We therefore conclude that the BLAST detection is likely contaminated by emission from foreground galaxies associated with the Bullet Cluster. The submillimeter redshift estimate based on 250-1100 mm photometry at the position of the AzTEC source is z phot = 2.9+0.6 -0.3, consistent with the infrared color redshift estimation of the most likely Infrared Array Camera counterpart. These flux densities indicate an apparent far-infrared (FIR) luminosity of L FIR = 2 x 1013 L . When the amplification due to the gravitational lensing of the cluster is removed, the intrinsic FIR luminosity of the source is found to be L FIR [?] 1012 L , consistent with typical luminous infrared galaxies.