A major goal of the Atacama Large Millimeter/submillimeter Array (ALMA) is to make accurate images with resolutions of tens of milliarcseconds, which at submillimeter (submm) wavelengths requires baselines up to ∼15 km. To develop and test this capability, a Long Baseline Campaign (LBC) was carried out from 2014 September to late November, culminating in end-to-end observations, calibrations, and imaging of selected Science Verification (SV) targets. This paper presents an overview of the campaign and its main results, including an investigation of the short-term coherence properties and systematic phase errors over the long baselines at the ALMA site, a summary of the SV targets and observations, and recommendations for science observing strategies at long baselines. Deep ALMA images of the quasar 3C 138 at 97 and 241 GHz are also compared to VLA 43 GHz results, demonstrating an agreement at a level of a few percent. As a result of the extensive program of LBC testing, the highly successful SV imaging at long baselines achieved angular resolutions as fine as 19 mas at ∼350 GHz. Observing with ALMA on baselines of up to 15 km is now possible, and opens up new parameter space for submm astronomy.

We present results from a continuing interferometric survey of high-redshift submillimeter galaxies with the Submillimeter Array, including high-resolution (beam size ∼ 2 arcsec) imaging of eight additional AzTEC 1.1mm selected sources in the COSMOS Field, for which we obtain six reliable (peak 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 followup. With this sample in hand, we (1) empirically confirm the radio-submillimeter association, (2) examine the submillimeter morphology -including the nature of submillimeter galaxies 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 submillimeter galaxies 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 formationwhich struggle to account for such objects even under liberal assumptions -and dust production models given the limited time since the Big Bang.

Abstract.Using the Effelsberg 100-m telescope, detections of four extragalactic water vapor masers are reported. Isotropic luminosities are ∼50, 1000, 1 and 230 L for Mrk 1066 (UGC 2456), Mrk 34, NGC 3556 and Arp 299, respectively. Mrk 34 contains by far the most distant and one of the most luminous water vapor megamasers so far reported in a Seyfert galaxy. The interacting system Arp 299 appears to show two maser hotspots separated by approximately 20 . With these new results and even more recent data from Braatz et al. (2004, ApJ, 617, L29), the detection rate in our sample of Seyferts with known jet-Narrow Line Region interactions becomes 50% (7/14), while in star forming galaxies with high (S 100 µm > 50 Jy) far infrared fluxes the detection rate is 22% (10/45). The jet-NLR interaction sample may not only contain "jet-masers" but also a significant number of accretion "disk-masers" like those seen in NGC 4258. A statistical analysis of 53 extragalactic H 2 O sources (excluding the Galaxy and the Magellanic Clouds) indicates (1) that the correlation between IRAS Point Source and H 2 O luminosities, established for individual star forming regions in the galactic disk, also holds for AGN-dominated megamaser galaxies; (2) that maser luminosities are not correlated with 60 µm/100 µm color temperatures; and (3) that only a small fraction of the luminous megamasers (L H 2 O > 100 L ) detectable with 100-m sized telescopes have so far been identified. The H 2 O luminosity function (LF) suggests that the number of galaxies with 1 L < L H 2 O < 10 L , the transition range between "kilomasers" (mostly star formation) and "megamasers" (active galactic nuclei), is small. The overall slope of the LF, ∼−1.5, indicates that the number of detectable masers is almost independent of their luminosity. If the LF is not steepening at very high maser luminosities and if it is possible to find suitable candidate sources, H 2 O megamasers at significant redshifts should be detectable even with present day state-of-the-art facilities.

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of the [CII] 157.7µm fine structure line and thermal dust continuum emission from a pair of gas-rich galaxies at z = 4.7, BR1202-0725. This system consists of a luminous quasar host galaxy and a bright submm galaxy (SMG), while a fainter star-forming galaxy is also spatially coincident within a 4 ′′ (25 kpc) region. All three galaxies are detected in the submm continuum, indicating FIR luminosities in excess of 10 13 L ⊙ for the two most luminous objects. The SMG and the quasar host galaxy are both detected in [CII] line emission with luminosities, L [CII] = (10.0 ± 1.5) × 10 9 L ⊙ and L [CII] = (6.5 ± 1.0) × 10 9 L ⊙ , respectively. We estimate a luminosity ratio, L [CII] /L FIR = (8.3 ± 1.2) × 10 −4 for the starburst -2 -SMG to the North, and L [CII] /L FIR = (2.5±0.4)×10 −4 for the quasar host galaxy, in agreement with previous high-redshift studies that suggest lower [CII]-to-FIR luminosity ratios in quasars than in starburst galaxies. The third fainter object with a flux density, S 340GHz = 1.9 ± 0.3 mJy, is coincident with a Ly-α emitter and is detected in HST ACS F775W and F814W images but has no clear counterpart in the H -band. Even if this third companion does not lie at a similar redshift to BR1202-0725, the quasar and the SMG represent an overdensity of massive, infrared luminous star-forming galaxies within 1.3 Gyr of the Big Bang.1 We define FIR luminosity as L FIR integrated over restframe 40-500µm.

Using a combination of observations involving the Very Large Array (VLA), MERLIN and global Very Long Baseline Interferometry (VLBI) networks we have made a detailed study of the radio continuum and the neutral hydrogen (H i) kinematics and distribution within the central kiloparsec of the radio galaxy 3C 293. These observations trace the complex jet structure and identify the position of the steeply inverted radio core at 1.3 GHz. Strong H i absorption is detected against the majority of the inner kiloparsec of 3C 293. This absorption is separated into two dynamically different and spatially resolved systems. Against the eastern part of the inner radio jet, narrow H i absorption is detected and shown to have higher optical depths in areas cospatial with a central dust lane. Additionally, this narrow line is shown to follow a velocity gradient of ∼50 km s−1 arcsec−1, consistent with the velocity gradient observed in optical spectroscopy of ionized gas. We conclude that the narrow H i absorption, dust and ionized gas are physically associated and situated several kiloparsecs from the centre of the host galaxy. Against the western jet emission and core component, broad and complex H i absorption is detected. This broad and complex absorption structure is discussed in terms of two possible interpretations for the gas kinematics observed. We explore the possibility that these broad, double absorption spectra are the result of two gas layers at different velocities and distances along these lines of sight. A second plausible explanation for this absorbing structure is that the H i is situated in rotation about the core of this radio galaxy with some velocity dispersion resulting from infall and outflow of gas from the core region. If the latter explanation were correct, then the mass enclosed by the rotating disc would be at least 1.7 × 109 solar masses within a radius of 400 pc.

We present broad-band radio observations of the afterglow of GRB 000301C, spanning from 1.4 to 350 GHz for the period of 3 to 83 days after the burst. This radio data, in addition to measurements at the optical bands, suggest that the afterglow arises from a collimated outflow, i.e. a jet. To test this hypothesis in a self-consistent manner, we employ a global fit and find that a model of a jet, expanding into a constant density medium (ISM+jet), provides the best fit to the data. A model of the burst occurring in a wind-shaped circumburst medium (wind-only model) can be ruled out, and a wind+jet model provides a much poorer fit of the optical/IR data than the ISM+jet model. In addition, we present the first clear indication that the reported fluctuations in the optical/IR are achromatic with similar amplitudes in all bands, and possibly extend into the radio regime. Using the parameters derived from the global fit, in particular a jet break time, t jet ≈ 7.5 days, we infer a jet opening angle of θ 0 ≈ 0.2, and consequently the estimate of the emitted energy in the GRB itself is reduced by a factor ∼50 relative to the isotropic value, giving E ≈ 1.1 × 10 51 ergs.

Abstract. The detection of 22 GHz water vapor emission from IC 342 is reported, raising the detection rate among northern galaxies with IRAS point source fluxes S100 µm > 50 Jy to 16%. The maser, associated with a star forming region ∼10-15 west of the nucleus, consists of a single 0.5 km s −1 wide feature and reaches an isotropic luminosity of 10 −2 L (D = 1.8 Mpc). If the time variability is intrinsic, the maser size is < ∼ 1.5×10 16 cm ( < ∼ 0.5 mas) which corresponds to a brightness temperature of > ∼ 10 9 K. The linewidth, luminosity, and rapid variability are reminiscent of the 8 km s −1 super maser in Orion-KL. A velocity shift of 1 km s −1 within two weeks and subsequent rapid fading is explained in terms of a chance alignment of two dense molecular clouds. Observations at 22 GHz toward Maffei 2 are also reported, yielding a 5σ upper limit of 25 mJy for a channel spacing of 1.05 km s −1 .

We present Very Long Baseline Array (VLBA) observations of the gigamaser galaxy TXS 2226À184 at 1.3 and 5 GHz. These observations reveal the parsec-scale radio structure of this Seyfert galaxy with exceptionally luminous water maser emission. The source is found to be extended on scales of 10-100 pc with some embedded compact sources, but it has no readily identifiable flat-spectrum active nucleus. This morphology resembles that of the nearby compact starburst galaxy Mrk 273, although no significant far-infrared emission has been detected to support the starburst scenario. The narrow (125 km s À1 ) H i absorption in TXS 2226À184 discovered with the Very Large Array (VLA) is also detected with the VLBA. This H i absorption is distributed across the extended emission, probably cospatial with the water masers. The broad (420 km s À1 ) line seen by the VLA is not detected, suggesting that it arises from more extended gas that is absorbing the emission beyond the central tens of parsecs.