Search

We present initial results of very high resolution Atacama Large Millimeter/submillimeter Array (ALMA) observations of the $z$=3.042 gravitationally lensed galaxy HATLAS J090311.6+003906 (SDP.81). These observations were carried out using a very extended configuration as part of Science Verification for the 2014 ALMA Long Baseline Campaign, with baselines of up to 15 km. We present continuum imaging at 151, 236 and 290 GHz, at unprecedented angular resolutions as fine as 23 milliarcseconds (mas), corresponding to an un-magnified spatial scale of ~180 pc at z=3.042. The ALMA images clearly show two main gravitational arc components of an Einstein ring, with emission tracing a radius of ~1.5". We also present imaging of CO(10-9), CO(8-7), CO(5-4) and H2O line emission. The CO emission, at an angular resolution of ~170 mas, is found to broadly trace the gravitational arc structures but with differing morphologies between the CO transitions and compared to the dust continuum. Our detection of H2O line emission, using only the shortest baselines, provides the most resolved detection to date of thermal H2O emission in an extragalactic source. The ALMA continuum and spectral line fluxes are consistent with previous Plateau de Bure Interferometer and Submillimeter Array observations despite the impressive increase in angular resolution. Finally, we detect weak unresolved continuum emission from a position that is spatially coincident with the center of the lens, with a spectral index that is consistent with emission from the core of the foreground lensing galaxy., Comment: 9 pages, 5 figures and 3 tables, accepted for publication in the Astrophysical Journal Letters

We present Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm continuum images of the asteroid 3 Juno obtained with an angular resolution of 0.042 arcseconds (60 km at 1.97 AU). The data were obtained over a single 4.4 hr interval, which covers 60% of the 7.2 hr rotation period, approximately centered on local transit. A sequence of ten consecutive images reveals continuous changes in the asteroid's profile and apparent shape, in good agreement with the sky projection of the three-dimensional model of the Database of Asteroid Models from Inversion Techniques. We measure a geometric mean diameter of 259pm4 km, in good agreement with past estimates from a variety of techniques and wavelengths. Due to the viewing angle and inclination of the rotational pole, the southern hemisphere dominates all of the images. The median peak brightness temperature is 215pm13 K, while the median over the whole surface is 197pm15 K. With the unprecedented resolution of ALMA, we find that the brightness temperature varies across the surface with higher values correlated to the subsolar point and afternoon areas, and lower values beyond the evening terminator. The dominance of the subsolar point is accentuated in the final four images, suggesting a reduction in the thermal inertia of the regolith at the corresponding longitudes, which are possibly correlated to the location of the putative large impact crater. These results demonstrate ALMA's potential to resolve thermal emission from the surface of main belt asteroids, and to measure accurately their position, geometric shape, rotational period, and soil characteristics., Comment: 8 pages, 3 figures, 2 tables, accepted for publication in the Astrophysical Journal Letters

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations from the 2014 Long Baseline Campaign in dust continuum and spectral line emission from the HL Tau region. The continuum images at wavelengths of 2.9, 1.3, and 0.87 mm have unprecedented angular resolutions of 0.075 arcseconds (10 AU) to 0.025 arcseconds (3.5 AU), revealing an astonishing level of detail in the circumstellar disk surrounding the young solar analogue HL Tau, with a pattern of bright and dark rings observed at all wavelengths. By fitting ellipses to the most distinct rings, we measure precise values for the disk inclination (46.72pm0.05 degrees) and position angle (+138.02pm0.07 degrees). We obtain a high-fidelity image of the 1.0 mm spectral index ($\alpha$), which ranges from $\alpha\sim2.0$ in the optically-thick central peak and two brightest rings, increasing to 2.3-3.0 in the dark rings. The dark rings are not devoid of emission, we estimate a grain emissivity index of 0.8 for the innermost dark ring and lower for subsequent dark rings, consistent with some degree of grain growth and evolution. Additional clues that the rings arise from planet formation include an increase in their central offsets with radius and the presence of numerous orbital resonances. At a resolution of 35 AU, we resolve the molecular component of the disk in HCO+ (1-0) which exhibits a pattern over LSR velocities from 2-12 km/s consistent with Keplerian motion around a ~1.3 solar mass star, although complicated by absorption at low blue-shifted velocities. We also serendipitously detect and resolve the nearby protostars XZ Tau (A/B) and LkHa358 at 2.9 mm., Comment: 11 pages, 5 figures, 2 tables, accepted for publication in the Astrophysical Journal Letters

We present the stellar and ionized gas kinematics of 13 bright peculiar Virgo cluster galaxies observed with the DensePak Integral Field Unit at the WIYN 3.5-meter telescope, to seek kinematic evidence that these galaxies have experienced gravitational interactions or gas stripping. 2-Dimensional maps of the stellar velocity $V$, and stellar velocity dispersion $\sigma$ and the ionized gas velocity (H$\beta$ and/or [\ion{O}{3}]) are presented for galaxies in the sample. The stellar rotation curves and velocity dispersion profiles are determined for 13 galaxies, and the ionized gas rotation curves are determined for 6 galaxies. Misalignments between the optical and kinematical major axis are found in several galaxies. While in some cases this is due to a bar, in other cases it seems associated with a gravitational interaction or ongoing ram pressure stripping. Non-circular gas motions are found in nine galaxies, with various causes including bars, nuclear outflows, or gravitational disturbances. Several galaxies have signatures of kinematically distinct stellar components, which are likely signatures of accretion or mergers. We compute for all galaxies the angular momentum parameter $\lambda_{\rm R}$. An evaluation of the galaxies in the $\lambda_{\rm R}$-ellipticity plane shows that all but 2 of the galaxies have significant support from random stellar motions, and have likely experienced gravitational interactions. This includes some galaxies with very small bulges and truncated/compact H$\alpha$ morphologies, indicating that such galaxies cannot be fully explained by simple ram pressure stripping, but must have had significant gravitational encounters. Most of the sample galaxies show evidence for ICM-ISM stripping as well as gravitational interactions, indicating that the evolution of a significant fraction of cluster galaxies is likely strongly impacted by both effects., Comment: 45 pages, 14 figures, ApJS accepted, emulateapj version

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of the [CII] 157.7micron 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 Lsun 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)x10^9 Lsun and L([CII]) = (6.5+/-1.0)x10^9 Lsun, respectively. We estimate a luminosity ratio, L([CII])/L(FIR) = (8.3+/-1.2)x10^-4 for the starburst SMG to the North, and L([CII])/L(FIR) = (2.5+/-0.4)x10^-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-Alpha 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., Comment: 14 pages, accepted for publication in ApJ Letters

Infalling motions were detected and modeled toward this source. A mean infall velocity of 0.5 km/s with an infall mass rate of 5x10^-3 Solar masses per year was obtained. Also, a previously estimated value for the magnetic field strength in the plane of the sky was refined to be 855 micro Gauss which we used to calculate a mass-to-magnetic flux ratio of 1.9, or super-critical. The virial mass from turbulent motions was also calculated finding Mvir=563 solar masses, which gives a ratio of Msubmm/Mvir=5.9. Both values strongly suggest that this clump must be in a state of gravitational collapse., Comment: Accepted for publication by Astronomy and Astrophysics

We present a detailed study of the peculiar HI-deficient Virgo cluster spiral galaxies NGC 4064 and NGC 4424, using $^{12}$CO 1-0 interferometry, optical imaging and integral-field spectroscopic observations, in order to learn what type of environmental interactions have afected these galaxies. Optical imaging reveals that NGC 4424 has a strongly disturbed stellar disk, with banana-shaped isophotes and shells. NGC 4064, which lies in the cluster outskirts, possesses a relatively undisturbed outer stellar disk and a central bar. In both galaxies H-alpha emission is confined to the central kiloparsec. CO observations reveal bilobal molecular gas morphologies, with H-alpha emission peaking inside the CO lobes, implying a time sequence in the star formation process.Gas kinematics reveals strong bar-like non-circular motions in the molecular gas in both galaxies, suggesting that the material is radially infalling. In NGC 4064 the stellar kinematics reveal strong bar-like non-circular motions in the central 1 kpc. On the other hand, NGC 4424 has extremely modest stellar rotation velocities (Vmax ~ 30 km s-1), and stars are supported by random motions as far out as we can measure it. The observations suggest that the peculiarities of NGC 4424 are the result of an intermediate-mass merger plus ram pressure stripping. In the case of NGC 4064, the evidence suggests an already stripped "truncated/normal" galaxy that recently suffered a minor merger or tidal interaction with another galaxy. We propose that galaxies with "truncated/compact" H-alpha morphologies such as these are the result of the independent effects of ram pressure stripping, which removes gas from the outer disk, and gravitational interactions such as mergers, which heat stellar disks, drive gas to the central kpc and increase the central mass concentrations., Comment: 42 pages, 21 figures