We report the first results from a survey for 1665, 1667, and 1720 MHz OH emission over a small region of the Outer Galaxy centered at $l \approx 105.0°, b \approx +1.0°$ . This sparse, high-sensitivity survey ($ΔTa \approx ΔTmb \approx 3.0 - 3.5$ mK rms in 0.55 km/s channels), was carried out as a pilot project with the Green Bank Telescope (GBT, FWHM $\approx 7.6'$) on a 3 X 9 grid at $0.5°$ spacing. The pointings chosen correspond with those of the existing $^{12}$CO(1-0) CfA survey of the Galaxy (FWHM $\approx 8.4'$). With 2-hr integrations, 1667 MHz OH emission was detected with the GBT at $\gtrsim 21$ of the 27 survey positions ($\geq 78\%$ ), confirming the ubiquity of molecular gas in the ISM as traced by this spectral line. With few exceptions, the main OH lines at 1665 and 1667 MHz appear in the ratio of 5:9 characteristic of LTE at our sensitivity levels. No OH absorption features are recorded in the area of the present survey, in agreement with the low levels of continuum background emission in this direction. At each pointing the OH emission appears in several components extending over a range of radial velocity and coinciding with well-known features of Galactic structure such as the Local Arm and the Perseus Arm. In contrast, little CO emission is seen in the survey area; less than half of the $\gtrsim 50$ identified OH components show detectable CO at the CfA sensitivity levels, and these are generally faint. There are no CO profiles without OH emission. With few exceptions, peaks in the OH profiles coincide with peaks in the GBT HI spectra (obtained concurrently, FWHM $8.9'$), although the converse is not true. We conclude that main-line OH emission is a promising tracer for the "dark molecular gas" in the Galaxy discovered earlier in Far-IR and gamma-ray emission. Further work is needed to establish the quantitative details of this connection.
We present a pilot program using IRAM's NOrthern Extended Millimeter Array (NOEMA) to probe the molecular gas reservoirs of six $z=0.6-1.1$ star-forming galaxies whose circumgalactic medium has been observed in absorption along quasar lines-of-sight as part of the MusE GAs FLOw and Wind (MEGAFLOW) survey and for which we have estimates of either the accretion or the outflow rate. This program is motivated by testing the quasi equilibrium model and the compaction scenario describing the evolution of galaxies along the main sequence of star formation, which imply tight relations between the gas …
We present a pilot, untargeted extragalactic carbon monoxide (CO) emission-line survey using ALMACAL, a project utilizing ALMA calibration data for scientific purposes. In 33 deep (Texp > 40 min) ALMACAL fields we report six CO emission-line detections above S/N > 4, one-third confirmed by MUSE observations. With this pilot survey, we probe a cosmologically significant volume of ~10^5 cMpc^3, widely distributed over many pointings in the southern sky, making the survey largely insusceptible to the effects of cosmic variance. We derive the redshift probability of the CO detections using probabi…
We present the first molecular gas mass survey of void galaxies. We compare these new data together with data for the atomic gas mass and star formation rate ($\rm SFR$) from the literature to those of galaxies in filaments and walls in order to better understand how molecular gas and star formation are related to the large-scale environment. We observed at the IRAM 30 m telescope the CO(1-0) and CO(2-1) emission of 20 void galaxies selected from the Void Galaxy Survey (VGS), with a stellar mass range from $\rm 10^{8.5}$ to $\rm 10^{10.3}M_{\odot}$. We detected 15 objects in at least one CO li…
The Radio Ammonia Mid-Plane Survey (RAMPS) is a molecular line survey that aims to map a portion of the Galactic midplane in the first quadrant of the Galaxy (l = 10 deg - 40 deg, |b| < 0.4 deg) using the Green Bank Telescope. We present results from the pilot survey, which has mapped approximately 6.5 square degrees in fields centered at l = 10 deg, 23 deg, 24 deg, 28 deg, 29 deg, 30 deg, 31 deg, 38 deg, 45 deg, and 47 deg. RAMPS observes the NH3 inversion transitions NH3(1, 1) - (5, 5), the H2O 6(1,6) - 5(2,3) maser line at 22.235 GHz, and several other molecular lines. We present a represen…
We present the first far infrared (FIR) dust emission polarization map covering the full extent Milky Way's Central molecular zone (CMZ). The data, obtained with the PILOT balloon-borne experiment, covers the Galactic Center region $-2\,^\circ<l<2\,^\circ$, $-4\,^\circ<b<3\,^\circ$ at a wavelength of 240 $μ$m and an angular resolution $2.2\,'$. From our measured dust polarization angles, we infer a magnetic field orientation projected onto the plane of the sky that is remarkably ordered over the full extent of the CMZ, with an average tilt angle of $\simeq 22\,^\circ$ clockwise with respect to…
We present a pilot HI survey of 17 Planck Galactic Cold Clumps (PGCCs) with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). HI Narrow Self-Absorption (HINSA) is an effective method to detect cold HI being mixed with molecular hydrogen H$_2$ and improves our understanding of the atomic to molecular transition in the interstellar medium. HINSA was found in 58\% PGCCs that we observed. The column density of HINSA was found to have an intermediate correlation with that of $^{13}$CO, following $\rm log( N(HINSA)) = (0.52\pm 0.26) log(N_{^{13}CO}) + (10 \pm 4.1) $. HI abundance rel…
WALLABY pilot survey: HI depletion times within the stellar discs of nearby galaxies
International Centre for Radio Astronomy Research (ICRAR), The University of Western Australia（西澳大利亚大学国际射电天文研究中心）；ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D)（三维全天空天体物理学卓越中心）；INAF, Arcetri Astrophysical Observatory（意大利国家天体物理研究所阿切特里天文台）
Using the Australian Square Kilometre Array Pathfinder to measure 21-cm absorption spectra toward continuum background sources, we study the cool phase of the neutral atomic gas in the far outer disk, and in the inner Galaxy near the end of the Galactic bar at longitude 340 degrees. In the inner Galaxy the cool atomic gas has a smaller scale height than in the solar neighborhood, similar to the molecular gas and the superthin stellar population in the bar. In the outer Galaxy the cool atomic gas is mixed with the warm, neutral medium, with the cool fraction staying roughly constant with Galact…
We present the most sensitive and detailed view of the neutral hydrogen (HI) emission associated with the Small Magellanic Cloud (SMC), through the combination of data from the Australian Square Kilometre Array Pathfinder (ASKAP) and Parkes (Murriyang), as part of the Galactic Australian Square Kilometre Array Pathfinder (GASKAP) pilot survey. These GASKAP-HI pilot observations, for the first time, reveal HI in the SMC on similar physical scales as other important tracers of the interstellar medium, such as molecular gas and dust. The resultant image cube possesses an rms noise level of 1.1 K …
The low-frequency sky may reveal some of the secrets yet to be discovered and until recently, molecules had never been detected within interstellar clouds at frequencies below 700MHz (Lovas, 2003) . Following the pilot survey towards the Galactic Centre at 103--133MHz with the Murchison Widefield Array (Tremblay, 2017), we surveyed 400 degree squared centered on the Orion KL nebula from 99--170MHz. Orion is a nearby region of active star formation and known to be a chemically rich environment. In this paper, we present tentative detections of nitric oxide and its isotopologues, singularly deut…
Atomic ionised regions with strong continuum emission are often associated with regions of high-mass star formation and low-frequency (<2GHz) observations of these regions are needed to help build star formation models. The region toward the Vela Supernova Remnant is particularly interesting as it is a complex structure of recent supernova explosions and molecular clouds containing a number of HII regions that are not well characterised. We searched publicly available catalogues for HII regions, both candidate and identified, which also have low-frequency emission. In the area of ~400 square d…
We report the results of a pilot program for a Green Bank Telescope (GBT) MUSTANG Galactic Plane survey at 3 mm (90 GHz), MGPS90. The survey achieves a typical $1σ$ depth of $1-2$ mJy beam$^{-1}$ with a 9" beam. We describe the survey parameters, quality assessment process, cataloging, and comparison with other data sets. We have identified 709 sources over seven observed fields selecting some of the most prominent millimeter-bright regions between $0°< \ell < 50°$ (total area $\approx 7.5 °^2$). The majority of these sources have counterparts at other wavelengths. By applying flux selection c…
We present a comprehensive study of the gas kinematics associated with density structures at different spatial scales in the filamentary infrared dark cloud, G034.43+00.24 (G34). This study makes use of the H13CO+ (1-0) molecular line data from the ALMA Three-millimeter Observations of Massive Star-forming regions (ATOMS) survey, which has spatial and velocity resolution of 0.04 pc and 0.2 km/s, respectively. Several tens of dendrogram structures have been extracted in the position-position-velocity space of H13CO+, which include 21 small-scale leaves and 20 larger-scale branches. Overall, the…
We present an analysis of local molecular clouds (-6 <VLSR< 30 km/s, i.e., <1.5 kpc) in the first Galactic quadrant (25.8° <l<49.7° and |b|<5°), a pilot region of the Milky Way Imaging Scroll Painting (MWISP) CO survey. Using the SCIMES algorithm to divide large molecular clouds into moderate-sized ones, we determined distances to 28 molecular clouds with the background-eliminated extinction-parallax (BEEP) method using the Gaia DR2 parallax measurements aided by AG and AV, and the distance ranges from 250 pc to about 1.5 kpc. These incomplete distance samples indicate a linear relationship be…
