- ID:
- ivo://CDS.VizieR/J/ApJ/720/555
- Title:
- COLA. III. AGN in compact IR galaxies
- Short Name:
- J/ApJ/720/555
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from 4.8GHz Very Large Array (VLA) and global very long baseline interferometry (VLBI) observations of the northern half of the moderate FIR luminosity (median L_IR_=10^11.01^L_{sun}_) COLA (Compact Objects in Low-power AGNs) sample of star-forming galaxies. VLBI sources are detected in a high fraction (20/90) of the galaxies observed. The radio luminosities of these cores (~10^21^W/Hz) are too large to be explained by radio supernovae or supernova remnants and we argue that they are instead powered by active galactic nuclei (AGNs). These sub-parsec scale radio cores are preferentially detected toward galaxies whose VLA maps show bright 100-500 parsec scale nuclear radio components. Since these latter structures tightly follow the FIR to radio-continuum correlation for star formation, we conclude that the AGN-powered VLBI sources are associated with compact nuclear starburst environments. The implications for possible starburst-AGN connections are discussed. The detected VLBI sources have a relatively narrow range of radio luminosity consistent with models in which intense compact Eddington-limited starbursts regulate the gas supply onto a central supermassive black hole. The high incidence of AGN radio cores in compact starbursts suggests little or no delay between the starburst phase and the onset of AGN activity.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/838/49
- Title:
- CO large-field observations around l=150{deg}
- Short Name:
- J/ApJ/838/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present large-field (4.25x3.75deg^2^) mapping observations toward the Galactic region centered at l=150{deg},b=3.5{deg} in the J=1-0 emission line of CO isotopologues (^12^CO, ^13^CO, and C^18^O), using the 13.7m millimeter-wavelength telescope of the Purple Mountain Observatory. Based on the ^13^CO observations, we reveal a filamentary cloud in the Local Arm at a velocity range of -0.5 to 6.5km/s. This molecular cloud contains 1 main filament and 11 sub-filaments, showing the so-called "ridge-nest" structure. The main filament and three sub-filaments are also detected in the C^18^O line. The velocity structures of most identified filaments display continuous distribution with slight velocity gradients. The measured median excitation temperature, line width, length, width, and linear mass of the filaments are ~9.28K, 0.85km/s, 7.30pc, 0.79pc, and 17.92M_{sun}_/pc, respectively, assuming a distance of 400pc. We find that the four filaments detected in the C^18^O line are thermally supercritical, and two of them are in the virialized state, and thus tend to be gravitationally bound. We identify in total 146 ^13^CO clumps in the cloud, about 77% of the clumps are distributed along the filaments. About 56% of the virialized clumps are found to be associated with the supercritical filaments. Three young stellar object candidates are also identified in the supercritical filaments, based on the complementary infrared data. These results indicate that the supercritical filaments, especially the virialized filaments, may contain star-forming activities.
- ID:
- ivo://CDS.VizieR/J/AJ/157/228
- Title:
- Cold Classical TNOs: LCs & rotational properties
- Short Name:
- J/AJ/157/228
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a survey of the rotational and physical properties of the dynamically low inclination Cold Classical (CC) trans-Neptunian objects (TNOs). The CCs are primordial planetesimals and contain information about our solar system and planet formation over the first 100 million years after the Sun's formation. We obtained partial/complete light curves for 42 CCs. We use statistical tests to derive general properties about the shape and rotational frequency distributions of the CCs and infer that they have slower rotations and are more elongated/deformed than the other TNOs. On the basis of the full light curves, the mean rotational period of the CCs is 9.48+/-1.53 hr compared to 8.45+/-0.58 hr for the rest of the TNOs. About 65% of the TNOs have a light-curve amplitude below 0.2 mag compared to the 36% of CCs with small amplitude. We present the full light curve of one likely contact binary, 2004 VC_131_, with a potential density of 1 g/cm^3^ for a mass ratio of 0.4. We have hints that 2004 MU_8_ and 2004 VU_75_ are perhaps potential contact binaries, on the basis of their sparse light curves, but more data are needed to confirm this finding. Assuming equal-sized binaries, we find that ~10%-25% of the CCs could be contact binaries, suggesting a deficit of contact binaries in this population compared to previous estimates and to the (~40%-50%) possible contact binaries in the Plutino population. These estimates are lower limits and may increase if nonequal-sized contact binaries are considered. Finally, we put in context the results of the New Horizons flyby of 2014 MU_69_.
3624. Cold galaxies
- ID:
- ivo://CDS.VizieR/J/MNRAS/453/2050
- Title:
- Cold galaxies
- Short Name:
- J/MNRAS/453/2050
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use 350 {mu}m angular diameter estimates from Planck to test the idea that some galaxies contain exceptionally cold (10-13 K) dust, since colder dust implies a lower surface brightness radiation field illuminating the dust, and hence a greater physical extent for a given luminosity. The galaxies identified from their spectral energy distributions as containing cold dust do indeed show the expected larger 350 {mu}m diameters. For a few cold dust galaxies where Herschel data are available, we are able to use submillimetre maps or surface brightness profiles to locate the cold dust, which as expected generally lies outside the optical galaxy.
- ID:
- ivo://CDS.VizieR/J/A+A/614/A3
- Title:
- 6 cold-gas-bearing debris-disc stars spectra
- Short Name:
- J/A+A/614/A3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Debris discs have often been described as gas-poor discs as the gas-to-dust ratio is expected to be considerably lower than in primordial, protoplanetary discs. However, recent observations have confirmed the presence of a non-negligible amount of cold gas in the circumstellar (CS) debris discs around young main-sequence stars. This cold gas has been suggested to be related to the outgassing of planetesimals and cometary-like objects. The goal of this paper is to investigate the presence of hot gas in the immediate surroundings of the cold-gas-bearing debris-disc central stars. High-resolution optical spectra of all currently known cold-gas-bearing debris-disc systems, with the exception of beta Pic and Fomalhaut, have been obtained from La Palma (Spain), La Silla (Chile), and La Luz (Mexico) observatories. To verify the presence of hot gas around the sample of stars, we have analysed the CaII H&K and the NaI D lines searching for non-photospheric absorptions of CS origin, usually attributed to cometary-like activity.
- ID:
- ivo://CDS.VizieR/J/A+A/564/A65
- Title:
- Cold gas properties of Herschel Reference Survey
- Short Name:
- J/A+A/564/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new ^12^CO(1-0) observations of 59 late-type galaxies belonging to the Herschel Reference Survey (HRS), a complete K-band-selected, volume-limited (15<=D<=25Mpc) sample of nearby galaxies spanning a wide range in morphological type and luminosity. We studied different recipes to correct single-beam observations of nearby galaxies of different sizes and inclinations for aperture effects. This was done by comparing single-beam and multiple-beam observations along the major axis, which were corrected for aperture effects using different empirical or analytical prescriptions, to integrated maps of several nearby galaxies, including edge-on systems observed by different surveys. The resulting recipe is an analytical function determined by assuming that late-type galaxies are 3D exponentially declining discs with a characteristic scale length r_CO_=0.2r_24.5_, where r_24.5_ is the optical, g- (or B-) band isophotal radius at the 24.5mag/arcsec^2^ (25mag/arcsec^2^), as well as a scale height z_CO_=1/100r_24.5_. Our new CO data are then combined with those available in the literature to produce the most updated catalogue of CO observations for the HRS, now including 225 out of the 322 galaxies of the complete sample. The 3D exponential disc integration is applied to all the galaxies of the sample to measure their total CO fluxes, which are later transformed into molecular gas masses using a constant and a luminosity-dependent X_CO_ conversion factor. We also collect HI data for 315 HRS galaxies from the literature and present it in a homogenised form.
3627. COLD GASS survey
- ID:
- ivo://CDS.VizieR/J/MNRAS/415/32
- Title:
- COLD GASS survey
- Short Name:
- J/MNRAS/415/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We are conducting COLD GASS, a legacy survey for molecular gas in nearby galaxies. Using the IRAM 30-m telescope, we measure the CO(1-0) line in a sample of ~350 nearby (D_I_~=100-200Mpc), massive galaxies (log(M*/M_{sun}_)>10.0). The sample is selected purely according to stellar mass, and therefore provides an unbiased view of molecular gas in these systems. By combining the IRAM data with Sloan Digital Sky Survey (SDSS) photometry and spectroscopy, GALEX imaging and high-quality Arecibo HI data, we investigate the partition of condensed baryons between stars, atomic gas and molecular gas in 0.1-10L* galaxies. In this paper, we present CO luminosities and molecular hydrogen masses for the first 222 galaxies. Description: To overcome this issue, the GALEX Arecibo SDSS Survey (GASS; Catinella et al. 2010, Cat. J/MNRAS/403/683) was designed to measure the neutral hydrogen content for a large, unbiased sample of ~1000 massive galaxies (M*>10^10^M_{sun}_), via longer pointed observations. GASS is a large programme currently under way at the Arecibo 305-m telescope, and is producing some of the first unbiased atomic gas scaling relations in the nearby Universe (Catinella et al. 2010, Cat. J/MNRAS/403/683; Schiminovich et al., 2010MNRAS.408..919S; Fabello et al., 2011MNRAS.411..993F). We are in the process of constructing a CO Legacy Data base for the GASS survey (COLD GASS), measuring the molecular gas content of a significant subsample of the GASS galaxies. We will then be able to quantify the link between atomic gas, molecular gas and stars in these systems.
- ID:
- ivo://CDS.VizieR/J/A+A/639/A26
- Title:
- Cold HI, H2 and total H column density FITS maps
- Short Name:
- J/A+A/639/A26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- There are significant amounts of H_2_ in the Milky Way. Due to its symmetry H_2_ does not radiate at radio frequencies. CO is thought to be a tracer for H_2_, however CO is formed at significantly higher opacities than H_2_. Thus, toward high Galactic latitudes significant amounts of H_2_ are hidden and called CO-dark. We demonstrate that the dust-to-gas ratio is a tool to identify locations and column densities of CO-dark H_2_. We adopt the hypothesis of a constant E(B-V)/NH ratio, independent of phase transitions from HI to H_2_. We investigate the Doppler temperatures T_D_, from a Gaussian decomposition of HI4PI data, to study temperature dependencies of E(B-V)/NHI. The E(B-V)/NHI ratio in the cold HI gas phase is high in comparison to the warmer one. We consider this as evidence that cold HI gas toward high Galactic latitudes is associated with H_2_. Beyond CO-bright regions we find for T_D_<1165K a correlation (NHI+2NH_2_)/NHI{prop.to}-log T_D_. In combination with a factor XCO=4.0x10^20^cm^-2^(K.km/s)^-1^ this yields for the full-sky NH/E(B-V)~5.1 to 6.7 10^21^cm^-2^mag^-1^, compatible with X-ray scattering and UV absorption line observations. Cold HI with T_D_<1165K contains on average 46% CO-dark H_2_. Prominent filaments have T_D_<220K and typical excitation temperatures Tex~50K. With a molecular gas fraction of >61% they are dominated dynamically by H_2_.
- ID:
- ivo://CDS.VizieR/J/ApJ/897/74
- Title:
- Cold & molecular clumps and YSOs within G15.684-0.29
- Short Name:
- J/ApJ/897/74
- Date:
- 11 Mar 2022
- Publisher:
- CDS
- Description:
- The bubble G15.684-0.29 has a radius of 15.7pc. Its large size indicates that it may have enough time to trigger star formation. We identify 39 dense cold clumps around the bubble from the HI-GAL survey. All of them satisfy the criteria for forming massive stars, and most of them lie in the bubble shell. We identify 19 molecular clumps around the bubble from the 12CO(3-2) survey, all of which are gravitationally bound. We found 9 Class I YSOs, 28 Class II YSOs, and 12 transition disks (TDs) around the bubble. For those young stellar objects (YSOs) located within the bubble boundary, 6 of 7 Class I YSOs lie in the shell, 15 of 22 Class II YSOs lie inside the bubble, and 3 of 5 TDs lie inside the bubble. The dynamical age of G15.684-0.29 in a turbulent medium is ~4Myr, which is much greater than the shell fragmentation time, ~0.82-1.74Myr. We suggest that triggered star formation may be ongoing in the shell of the bubble, and the collect and collapse model may work here. However, we cannot rule out the possibility that the radiation-driven implosion model may work on the formation of some YSOs. As we expected, the larger bubble has a much longer dynamical age, but we failed to find a clear age gradient for YSOs around the bubble.
- ID:
- ivo://CDS.VizieR/J/ApJ/697/207
- Title:
- Cold stellar stream orbit fit
- Short Name:
- J/ApJ/697/207
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use velocity and metallicity information from Sloan Digital Sky Survey and Sloan Extension for Galactic Understanding and Exploration stellar spectroscopy to fit an orbit to the narrow 63{deg} stellar stream of Grillmair and Dionatos (GD; 2006ApJ...643L..17G). The stars in the stream have a retrograde orbit with eccentricity e=0.33 (perigalacticon of 14.4kpc and apogalacticon of 28.7kpc) and inclination approximately i~35{deg}. In the region of the orbit which is detected, it has a distance of about 7-11kpc from the Sun. Assuming a standard disk plus bulge and logarithmic halo potential for the Milky Way stars plus dark matter, the stream stars are moving with a large space velocity of approximately 276km/s at perigalacticon. Using this stream alone, we are unable to determine if the dark matter halo is oblate or prolate. The metallicity of the stream is [Fe/H]=-2.1+/-0.1. Observed proper motions for individual stream members above the main sequence turnoff are consistent with the derived orbit. None of the known globular clusters in the Milky Way have positions, radial velocities, and metallicities that are consistent with being the progenitor of the GD-1 stream.