- ID:
- ivo://CDS.VizieR/J/ApJ/688/290
- Title:
- GASS HI survey of the lower halo
- Short Name:
- J/ApJ/688/290
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have detected over 400 HI clouds in the lower halo of the Galaxy within the pilot region of the Galactic All-Sky Survey (GASS), a region of the fourth quadrant that spans 18{deg} in longitude, 40{deg} in latitude, and is centered on the Galactic equator. These clouds have a median peak brightness temperature of 0.6K, a median velocity width of 12.8km/s, and angular sizes <~1{deg}. The motion of these clouds is dominated by Galactic rotation with a random cloud-to-cloud velocity dispersion of 18km/s. A sample of clouds likely to be near tangent points was analyzed in detail. These clouds have radii on the order of 30pc and a median HI mass of 630M_{sun}_. The population has a vertical scale height of 400pc and is concentrated in Galactocentric radius, peaking at R=3.8kpc. This confined structure suggests that the clouds are linked to spiral features, while morphological evidence that many clouds are aligned with loops and filaments is suggestive of a relationship with star formation. The clouds might result from supernovae and stellar winds in the form of fragmenting shells and gas that has been pushed into the halo rather than from a galactic fountain.
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- ID:
- ivo://CDS.VizieR/J/ApJ/764/74
- Title:
- GASS HVCs in the Magellanic Leading Arm region
- Short Name:
- J/ApJ/764/74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of high-velocity clouds in the region of the Magellanic Leading Arm. The catalog is based on neutral hydrogen (H I) observations from the Parkes Galactic All-Sky Survey. Excellent spectral resolution allows clouds with narrow-line components to be resolved. The total number of detected clouds is 419. We describe the method of cataloging and present the basic parameters of the clouds. We discuss the general distribution of the high-velocity clouds and classify the clouds based on their morphological type. The presence of a significant number of head-tail clouds and their distribution in the region is discussed in the context of Magellanic System simulations. We suggest that ram-pressure stripping is a more important factor than tidal forces for the morphology and formation of the Magellanic Leading Arm and that different environmental conditions might explain the morphological difference between the Magellanic Leading Arm and Magellanic Stream. We also discuss a newly identified population of clouds that forms the LA IV and a new diffuse bridge-like feature connecting the LA II and III complexes.
- ID:
- ivo://CDS.VizieR/J/ApJ/776/74
- Title:
- GASS VII. Bivariate HI-stellar mass function
- Short Name:
- J/ApJ/776/74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the bivariate neutral atomic hydrogen (HI)-stellar mass function (HISMF) {phi}(M_HI_, M_{star}_) for massive (logM_*_/M_{sun}_>10) galaxies derived from a sample of 480 local (0.025<z<0.050) galaxies observed in H I at Arecibo as part of the GALEX Arecibo SDSS Survey. We fit six different models to the HISMF and find that a Schechter function that extends down to a 1% HI gas fraction, with an additional fractional contribution below that limit, is the best parameterization of the HISMF. We calculate {Omega}_HI,M_{star}__>10^10^ and find that massive galaxies contribute 41% of the H I density in the local universe. In addition to the binned HISMF, we derive a continuous bivariate fit, which reveals that the Schechter parameters only vary weakly with stellar mass: M_HI_^*^, the characteristic H I mass, scales as M_{star}_^0.39^; {alpha}, the slope of the HISMF at moderate H I masses, scales as M_{star}_^0.07^; and f, the fraction of galaxies with HI gas fraction greater than 1%, scales as M_{star}_^-0.24^. The variation of f with stellar mass should be a strong constraint for numerical simulations. To understand the physical mechanisms that produce the shape of the HISMF, we redefine the parameters of the Schechter function as explicit functions of stellar mass and star formation rate (SFR) to produce a trivariate fit. This analysis reveals strong trends with SFR. While M_HI_^*^ varies weakly with stellar mass and SFR (M_HI_^*^{prop.to}M_{star}_^0.22^, M_HI_^*^{prop.to}SFR^-0.03^), {alpha} is a stronger function of both stellar mass and especially SFR ({alpha}{prop.to}M_{star}_^0.47^, {alpha}{prop.to}SFR^0.95^). The HISMF is a crucial tool that can be used to constrain cosmological galaxy simulations, test observational predictions of the H I content of populations of galaxies, and identify galaxies whose properties deviate from average trends.
- ID:
- ivo://CDS.VizieR/J/MNRAS/443/1044
- Title:
- GBT HI observations of 1194 spirals
- Short Name:
- J/MNRAS/443/1044
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present HI 21cm observations of 1194 galaxies out to a redshift of 10000km/s selected as inclined spirals (i>~60{deg}) from the 2MASS redshift survey. These observations were carried out at the National Radio Astronomy Observatory Robert C. Byrd Green Bank Telescope (GBT). This observing programme is part of the 2MASS Tully-Fisher (2MTF) survey. This project will combine Hi widths from these GBT observations with those from further dedicated observing at the Parkes Telescope, from the Arecibo Legacy Fast Arecibo L-band Feed Array survey at Arecibo, and S/N>10 and spectral resolution v_res_<10km/s published widths from a variety of telescopes. We will use these Hi widths along with 2MASS photometry to estimate Tully-Fisher distances to nearby spirals and investigate the peculiar velocity field of the local Universe. In this paper, we report on detections of neutral hydrogen in emission in 727 galaxies, and measure good signal to noise and symmetric HI global profiles suitable for use in the Tully-Fisher relation in 484.
- ID:
- ivo://CDS.VizieR/J/ApJ/902/39
- Title:
- GBT HI obs. of ultradiffuse galaxies
- Short Name:
- J/ApJ/902/39
- Date:
- 10 Mar 2022 13:55:53
- Publisher:
- CDS
- Description:
- We present neutral hydrogen (HI) observations using the Robert C. Byrd Green Bank Telescope (GBT) of 70 optically detected UDG candidates in the Coma region from the Systematically Measuring Ultra-Diffuse Galaxies survey (SMUDGes). We detect HI in 18 targets, confirming nine to be gas-rich UDGs and the remainder to be foreground dwarfs. None of our HI-detected UDGs are Coma Cluster members and all but one are in low-density environments. The HI-detected UDGs are bluer and have more irregular morphologies than the redder, smoother candidates not detected in HI, with the combination of optical color and morphology being a better predictor of gas richness than either parameter alone. There is little visual difference between the gas-rich UDGs and the foreground dwarfs in the SMUDGes imaging, and distances are needed to distinguish between them. We find that the gas richnesses of our HI-confirmed UDGs and those from other samples scale with their effective radii in two stellar mass bins, possibly providing clues to their formation. We attempt to place our UDGs on the baryonic Tully-Fisher relation (BTFR) using optical ellipticities and turbulence-corrected HI line widths to estimate rotation velocities, but the potential systematics associated with fitting smooth Sersic profiles to clumpy, low-inclination disks of low surface brightness precludes a meaningful analysis of potential BTFR offsets. These observations are a pilot for a large campaign now under way at the GBT to use the HI properties of gas-rich UDGs to quantitatively constrain how these galaxies form and evolve.
- ID:
- ivo://CDS.VizieR/J/ApJS/149/343
- Title:
- Giant molecular clouds in M33
- Short Name:
- J/ApJS/149/343
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first interferometric ^12^CO (J=1->0) map of the entire H{alpha} disk of M33. The 13" diameter synthesized beam corresponds to a linear resolution of 50pc, sufficient to distinguish individual giant molecular clouds (GMCs). From these data we generated a catalog of 148 GMCs with an expectation that no more than 15 of the sources are spurious. The catalog is complete down to GMC masses of 1.5x10^5^M_{sun}_ and contains a total mass of 2.3x10^7^M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/ApJS/81/5
- Title:
- Green Bank neutral hydrogen survey
- Short Name:
- J/ApJS/81/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Neutral hydrogen observations at 21cm, made at the Green Bank 91m telescope in 1984, 1985 and 1986, of a large sample of dwarf and other low surface brightness galaxies are presented. The majority of galaxies classified in the Uppsala General Catalogue as dwarf, irregular, Sdm, or later and with declinations north of the range of the Arecibo telescope ({delta}>38{deg}) have been observed, along with a number of galaxies farther south for flux comparisons with Arecibo observations (Schneider et al., 1990ApJS...72..245S, Paper I), totaling over 600 galaxies. About half of these galaxies have no previously published detections. In total, counting previous detections, over 80% of these late-type systems are detected at Green Bank. We have examined the galaxies for potential confusion with nearby galaxies, and we also present substantially better signal-to-noise measurements for many previously detected galaxies. Some general results of the Green Bank survey are discussed here, but the total data base of northern dwarf and low surface brightness galaxies, including new measurements of the galaxies' photographic magnitudes, will be examined in subsequent papers.
- ID:
- ivo://CDS.VizieR/J/A+A/569/A68
- Title:
- Green Bank Telescope observations of NGC 2403
- Short Name:
- J/A+A/569/A68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observed HI accretion around nearby galaxies can only account for a fraction of the gas supply needed to sustain the currently observed star formation rates. It is possible that additional accretion happens in the form of low column density cold flows, as predicted by numerical simulations of galaxy formation. To contrain the presence and properties of such flows, we present deep HI observations obtained with the NRAO Green Bank Telescope of an area measuring 4 by 4 degrees around NGC 2403. These observations, with a 5{sigma} detection limit of 2.4x10^18^cm^-2^ over a 20km/s linewidth, reveal the presence of a low-column density, extended cloud outside the main HI disk, about 17' (~16kpc or ~2R_25_) to the NW of the center of the galaxy. The total HI mass of the cloud is 6.3x10^6^M_{sun}_, or 0.15% of the total HI mass of NGC 2403. The cloud is associated with an 8kpc anomalous-velocity HI filament in the inner disk, previously observed in deep VLA observations by Fraternali et al. (2001ApJ...562L..47F, 2002AJ....123.3124F). We discuss several scenarios for the origin of the cloud, and conclude that it is either accreting from the intergalactic medium, or is the result of a minor interaction with a neigbouring dwarf galaxy.
- ID:
- ivo://CDS.VizieR/J/MNRAS/494/2090
- Title:
- Group galaxies in ALFALFA survey
- Short Name:
- J/MNRAS/494/2090
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We estimate the HI mass function (HIMF) of galaxies in groups based on thousands of ALFALFA (Arecibo Legacy Fast ALFA survey) HI detections within the galaxy groups of four widely used SDSS (Sloan Digital Sky Survey) groups catalogues. Although differences between the catalogues mean that there is no one definitive group galaxy HIMF, in general we find that the low-mass slope is flat, in agreement with studies based on small samples of individual groups, and that the 'knee' mass is slightly higher than that of the global HIMF of the full ALFALFA sample. We find that the observed fraction of ALFALFA galaxies in groups is approximately 22 per cent. These group galaxies were removed from the full ALFALFA source catalogue to calculate the field HIMF using the remaining galaxies. Comparison between the field and group HIMFs reveals that group galaxies make only a small contribution to the global HIMF as most ALFALFA galaxies are in the field, but beyond the HIMF 'knee' group galaxies dominate. Finally we attempt to separate the group galaxy HIMF into bins of group halo mass, but find that too few low-mass galaxies are detected in the most massive groups to tightly constrain the slope, owing to the rarity of such groups in the nearby Universe where low-mass galaxies are detectable with existing HI surveys.
- ID:
- ivo://CDS.VizieR/J/A+A/545/A16
- Title:
- Halpha3. Catalog and SFR in Virgo cluster
- Short Name:
- J/A+A/545/A16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present H{alpha}3 (acronym for H{alpha}-{alpha}{alpha}), an H{alpha} narrow-band imaging survey of ~400 galaxies selected from the HI Arecibo Legacy Fast ALFA Survey (ALFALFA) in the Local Supercluster, including the Virgo cluster. By using hydrogen recombination lines as a tracer of recent star formation, we aim to investigate the relationships between atomic neutral gas and newly formed stars in different environments (cluster and field), morphological types (spirals and dwarfs), and over a wide range of stellar masses (~10^7.5^-10^11.5^M_{sun}_). We image in H{alpha}+[NII] all the galaxies that contain more than 10^7^M_{sun}_ of neutral atomic hydrogen in the sky region 11h<R.A.<16h ; 4{deg}<Dec.<16{deg}; 350<cz<2000km/s using the San Pedro Martir 2m telescope. This survey provides a complete census of the star formation in HI rich galaxies of the local universe. We present the properties of the galaxy sample, together with H{alpha} fluxes and equivalent widths. We find an excellent agreement between the fluxes determined from our images in apertures of 3-arcsec diameter and the fluxes derived from the SDSS spectral database. From the H{alpha} fluxes corrected for galactic and internal extinction and for [NII] contamination we derive the global star formation rates (SFRs).
