- ID:
- ivo://CDS.VizieR/J/A+A/641/A151
- Title:
- NGC 7213 central region molecular gas
- Short Name:
- J/A+A/641/A151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multi-wavelength study (from X-ray to mm) of the nearby low-luminosity active galactic nucleus (LLAGN) NGC 7213. We combine the information from the different bands to characterise the source in terms of contribution from the AGN and the host-galaxy interstellar medium (ISM). This approach allows us to provide a coherent picture of the role of the AGN and its impact, if any, on the star formation and molecular gas properties of the host galaxy. We focused our study on archival ALMA Cycle 1 observations, where the CO(2-1) emission line has been used as a tracer of the molecular gas. Using the 3DBarolo code on ALMA data, we performed the modelling of the molecular gas kinematics traced by the CO(2-1) emission, finding a rotationally dominated pattern. The molecular gas mass of the host galaxy was estimated from the integrated CO(2-1) emission line obtained with APEX data, assuming an alpha_co conversion factor. Had we used the ALMA data, we would have underestimated the gas masses by a factor ~3, given the filtering out of the large-scale emission in interferometric observations. We also performed a complete X-ray spectral analysis on archival observations, revealing a relatively faint and unobscured AGN. The AGN proved to be too faint to significantly affect the properties of the host galaxy, such as star formation activity and molecular gas kinematics and distribution.
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- ID:
- ivo://CDS.VizieR/J/A+A/613/A3
- Title:
- NGC 1068 deep millimeter spectroscopy observations
- Short Name:
- J/A+A/613/A3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim for a better understanding of gas properties in the circum-nuclear disk (CND) region of the nearby gas-rich Seyfert 2 galaxy NGC 1068. We focus on line identification and the basic physical parameters estimation of molecular gas in the CND region. Methods. We used the IRAM 30m telescope to conduct deep millimeter spectroscopy observations toward the center of NGC 1068.
- ID:
- ivo://CDS.VizieR/J/A+A/634/A125
- Title:
- NGC 1068 nucleus molecular line spectra at 2mm
- Short Name:
- J/A+A/634/A125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the physical and chemical conditions of molecular gas in the circumnuclear disk (CND) region of NGC 1068. We carried out a spectral line survey with the IRAM 30m telescope toward the center of NGC 1068 and mainly focused on the 2mm band with a frequency coverage of 160.7-168.6GHz and 176.5-184.3GHz. Fifteen lines are detected in NGC 1068, eight of which are new detections for this galaxy. We derive the rotation temperatures and column densities of fourteen molecular species. Based on the [HCO^+^ (2-1)]/[HOC^+^ (2-1)] ratio, we obtain a high ionization degree in the CND of NGC 1068. It is found that HC_3_N is concentrated in the east knot, while ^13^CCH, CH_3_CN, SO, HOC^+^, CS, CH_3_CCH, and H_2_CO are concentrated in the west knot. Compared to the star-forming galaxies M 82 and NGC 253, the chemistry of NGC 1068 might be less strongly affected by the UV radiation field, and its kinetic temperature might be lower.
- ID:
- ivo://CDS.VizieR/J/A+A/587/A118
- Title:
- N2H+, N2D+ and C17O spectra in Ophiuchus
- Short Name:
- J/A+A/587/A118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In cold (T<25K) and dense (n_H_>10^4^cm^-3^) interstellar clouds, molecules such as CO are significantly frozen onto dust grain surfaces. Deuterium fractionation is known to be very efficient in these conditions as CO limits the abundance of H_3_^+^, which is the starting point of deuterium chemistry. In particular, N_2_D^+^ is an excellent tracer of dense and cold gas in star- forming regions. We measure the deuterium fraction, RD, and the CO depletion factor, fd, towards a number of starless and protostellar cores in the L1688 region of the Ophiuchus molecular cloud and search for variations based upon environmental differences across L1688. The kinematic properties of the dense gas traced by the N_2_H^+^ and N_2_D^+^ (1-0) lines are also discussed. Deuterium fraction has been measured via observations of the J=1-0 transition of N2H+ and N2D+ towards 33 dense cores in different regions of L1688. We estimated the CO depletion factor using C^17^O(1-0) and 850 micron dust continuum emission from the SCUBA survey. We carried out all line observations with the IRAM 30 meter antenna.
- ID:
- ivo://CDS.VizieR/J/A+A/642/A175
- Title:
- NIBLES bivariate luminosity function
- Short Name:
- J/A+A/642/A175
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a modified optical luminosity-HI mass bivariate luminosity function (BLF) based on HI line observations from the Nancay Interstellar Baryons Legacy Extragalactic Survey (NIBLES), including data from our new, four times more sensitive follow-up HI line observations obtained with the Arecibo radio telescope. The follow-up observations were designed to probe the underlying HI mass distribution of the NIBLES galaxies that were undetected or marginally detected in HI at the Radio Telescope. Our total follow-up sample consists of 234 galaxies, and it spans the entire luminosity and color range of the parent NIBLES sample of 2600 nearby (900<cz<12000km/s) SDSS galaxies. We incorporated the follow-up data into the bivariate analysis by scaling the NIBLES undetected fraction by an Arecibo-only distribution. We find the resulting increase in low HI mass-to-light ratio densities to be about 10% for the bins -1.0<=log(M/L)<=-0.5, which produces an increased HI mass function (HIMF) low mass slope of {alpha}=-1.14+/-0.07, being slightly shallower than the values of -1.35+/-0.05 obtained by recent blind HI surveys. Applying the same correction to the optically corrected bivariate luminosity function from our previous paper produces a larger density increase of about 0.5 to 1dex in the lowest HI mass-to-light ratio bins for a given luminosity while having a minimal effect on the resulting HIMF low mass slope, which still agrees with blind survey HIMFs. This indicates that while low HI-mass-to-light ratio galaxies do not contribute much to the one-dimensional HIMF, their inclusion has a significant impact on the densities in the two-dimensional distribution.
- ID:
- ivo://CDS.VizieR/J/ApJ/739/100
- Title:
- [NII] observations of the Carina Nebula (NGC 3372)
- Short Name:
- J/ApJ/739/100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a ~250arcmin^2^ mapping of the 205um [NII] fine-structure emission over the northern Carina Nebula, including the Car I and Car II HII regions. Spectra were obtained using the South Pole Imaging Fabry-Perot Interferometer (SPIFI) at the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO) at the South Pole. We supplement the 205um data with new reductions of far-IR fine-structure spectra from the Infrared Space Observatory (ISO) Long Wavelength Spectrometer (LWS) in 63um [OI], 122um [NII], 146um [OI], and 158um [CII]; the 146um [OI] data include 90 raster positions which have not been previously published. Morphological comparisons are made with optical, radio continuum, and CO maps. The 122/205 line ratio is used to probe the density of the low-ionization gas, and the 158/205 line ratio is used to probe the fraction of C^+^ arising from photodissociation regions (PDRs). The [OI] and [CII] lines are used to construct a PDR model of Carina. When the PDR properties are compared with other sources, Carina is found to be more akin to 30 Doradus than galactic star-forming regions such as Orion, M17, or W49; this is consistent with the view of Carina as a more evolved region, where much of the parent molecular cloud has been ionized or swept away. These data constitute the first ground-based detection of the 205um [NII] line, and the third detection overall since those of COBE FIRAS and the Kuiper Airborne Observatory in the early 1990s.
- ID:
- ivo://CDS.VizieR/J/A+A/646/A122
- Title:
- NOEMA millimeter reduced data cubes of HerBS-89a
- Short Name:
- J/A+A/646/A122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Exploiting the sensitivity of the IRAM NOrthern Extended Millimeter Array (NOEMA) and its ability to process large instantaneous bandwidths, we have studied the morphology and other properties of the molecular gas and dust in the starburst galaxy, H-ATLAS J131611.5+281219 (HerBS- 89a), at z=2.95. High angular resolution (0.3") images reveal a partial 1.0" diameter Einstein ring in the dust continuum emission and the molecular emission lines of ^12^CO(9-8) and H_2_O(2_02_-1_11_). Together with lower angular resolution (0.6") images, we report the detection of a series of molecular lines including the three fundamental transitions of the molecular ion OH+, namely (1_1_-0_1_), (1_2_-0_1_) and (1_0_-0_1_), seen in absorption; the molecular ion CH+(1-0) seen in absorption (and tentatively in emission); two transitions of amidogen (NH_2_), namely (2_02_-1_11_) and (2_20_-2_11_) seen in emission; and HCN(1_1_-1_0_) and/or NH(1_2_-0_1_) seen in absorption. The NOEMA data are complemented with Very Large Array data tracing the ^12^CO(1-0) emission line, which provides a measurement of the total mass of molecular gas and an anchor for a CO excitation analysis. In addition, we present Hubble Space Telescope imaging that reveals the foreground lensing galaxy in the near-infrared (1.15um). Together with photometric data from the Gran Telescopio Canarias, we derive a photometric redshift of zphot=0.9^+0.3^_-0.5_ for the foreground lensing galaxy. Modelling the lensing of HerBS-89a, we reconstruct the dust continuum (magnified by a factor {mu}~=5.0) and molecular emission lines (magnified by {mu}~4-5) in the source plane, which probe scales of ~0.1" (or 800pc). The ^12^CO(9-8) and H_2_O(2_02_-1_11_) emission lines have comparable spatial and kinematic distributions; the source-plane reconstructions do not clearly distinguish between a one-component and a two-component scenario, but the latter, which reveals two compact rotating components with sizes of ~=1kpc, that are likely merging, more naturally accounts for the broad line widths observed in HerBS-89a. In the core of HerBS-89a, very dense gas with n_H2_~10^7-9^cm^-3^ is revealed by the NH_2_ emission lines and the possible HCN(1_1_-1_0_) absorption line. HerBS-89a is a powerful star forming galaxy with a molecular gas mass of M_mol_=(2.1+/-0.4)x10^11^M_{sun}_, an infrared luminosity of L_IR_=(4.6+/-0.4)x10^12^L_{sun}_, and a dust mass of M_dust_=(2.6+/-0.2)x10^9^M_{sun}_, yielding a dust-to-gas ratio {delta}_GDR_~=80. We derive a star formation rate SFR=614+/-59M_{sun}_/yr and a depletion timescale {tau}_depl_=(3.4+/-1.0)x10^8^years. The OH+ and CH+ absorption lines, which trace low (~100cm^-3^) density molecular gas, all have their main velocity component red-shifted by {DELTA}V~100km/s relative to the global CO reservoir. We argue that these absorption lines trace a rare example of gas inflow towards the center of a starburst galaxy, indicating that HerBS-89a is accreting gas from its surroundings.
- ID:
- ivo://CDS.VizieR/J/A+A/440/151
- Title:
- Observations at 850um in Perseus clusters
- Short Name:
- J/A+A/440/151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a complete survey of current star formation in the Perseus molecular cloud, made at 850 and 450{mu} with SCUBA at the JCMT. Covering 3deg^2^, this submillimetre continuum survey for protostellar activity is second in size only to that of rho Ophiuchus (Johnstone et al., 2004ApJ...611L..45J). Complete above 0.4M_{sun}_ (5{sigma} detection in a 14" beam), we detect a total of 91 protostars and pre-stellar cores. Of these, 80% lie in clusters, representative of star formation across the Galaxy. Two of the groups of cores are associated with the young stellar clusters IC 348 and NGC 1333, and are consistent with a steady or reduced star formation rate in the last 0.5Myr, but not an increasing one. In Perseus, 40-60% of cores are in small clusters (<50M_{sun}_) and isolated objects, much more than the 10% suggested from infrared studies. Complementing the dust continuum, we present a C^18^O map of the whole cloud at 1' resolution.
- ID:
- ivo://CDS.VizieR/J/A+A/634/A115
- Title:
- Orion B9 dense cores H2D+ spectra
- Short Name:
- J/A+A/634/A115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to determine the ortho-H_2_D^+^ properties (e.g. column density and fractional abundance with respect to H_2_) in a sample of dense cores in the Orion B9 star-forming filament, and to compare those with the previously determined source characteristics, in particular with the gas kinetic temperature, [N_2_D^+^]/[N_2_H^+^] deuterium fractionation, and level of CO depletion. We used the Atacama Pathfinder EXperiment (APEX) telescope to observe the 372GHz o-H_2_D+(1_1,0_-1_1,1_) line towards three prestellar cores and three protostellar cores in Orion B9. We also employed our previous APEX observations of C^17^O, C^18^O, N_2_H^+^, and N_2_D^+^ line emission, and 870 micron dust continuum emission towards the target sources. The o-H_2_D^+^(1_1,0_-1_1,1_) line was detected in all three prestellar cores, but in _nly one of the protostellar cores. The corresponding o-H_2_D^+^ abundances were derived to be ~(12-30)x10^-11^ and ~6x10^-11^. Two additional spectral lines, DCO^+^(5-4) and N_2_H^+^(4-3), were detected in the observed frequency bands with high detection rates of 100% and 83%. We did not find any significant correlations among the explored parameters, although our results are mostly consistent with theoretical expectations. Also, the Orion B9 cores were found to be consistent with the relationship between the o-H_2_D^+^ abundance and gas temperature obeyed by other low-mass dense cores. The o-H_2_D^+^ abundance was found to decrease as the core evolves. The o-H_2_D^+^ abundances in the Orion B9 cores are in line with those found in other low-mass dense cores and larger than derived for high-mass star-forming regions. The higher o-H_2_D^+^ abundance in prestellar cores compared to that in cores hosting protostars is to be expected from chemical reactions where higher concentrations of gas-phase CO and elevated gas temperature accelerate the destruction of H_2_D^+^. The validity of using the [o-H_2_D^+^]/[N_2_D^+^] abundance ratio as an evolutionary indicator, which has been proposed for massive clumps, remains inconclusive when applied for the target cores. Similarly, the behaviour of the [o-H_2_D^+^]/[DCO^+^] ratio as the source evolves was found to be ambiguous. Still larger samples and observations of additional deuterated species are needed to explore these potential evolutionary indicators further. The low radial velocity of the line emission from one of the targeted prestellar cores, SMM 7 (~3.6km/s versus the systemic Orion B9 velocity of ~9km/s), suggests that it is a chance superposition seen towards Orion B9. Overall, as located in a dynamic environment of the Orion B molecular cloud, the Orion B9 filament provides an interesting target system to investigate the deuterium-based chemistry, and further observations of species like para-H_2_D^+^ and D_2_H^+^ would be of particular interest.
- ID:
- ivo://CDS.VizieR/J/A+A/641/A57
- Title:
- Oxygen-rich AGB IRAM spectra
- Short Name:
- J/A+A/641/A57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to determine the abundances of SiO, CS, SiS, SO, and SO_2_ in a large sample of oxygen-rich asymptotic giant branch (AGB) envelopes covering a wide range of mass loss rates to investigate the potential role that these molecules could play in the formation of dust in these environments. We surveyed a sample of 30 oxygen-rich AGB stars in the {lambda} 2mm band using the IRAM 30m telescope. We performed excitation and radiative transfer calculations based on the large velocity gradient (LVG) method to model the observed lines of the molecules and to derive their fractional abundances in the observed envelopes. We detected SiO in all 30 targeted envelopes, as well as CS, SiS, SO, and SO 2 in 18, 13, 26, and 19 sources, respectively. Remarkably, SiS is not detected in any envelope with a mass loss rate below 10^-6^M_{sun}_/yr, whereas it is detected in all envelopes with mass loss rates above that threshold. From a comparison with a previous, similar study on C-rich sources, it becomes evident that the fractional abundances of CS and SiS show a marked differentiation between C-rich and O-rich sources, being two orders of magnitude and one order of magnitude more abundant in C-rich sources, respectively, while the fractional abundance of SiO turns out to be insensitive to the C/O ratio. The abundance of SiO in O-rich envelopes behaves similarly to C-rich sources, that is, the denser the envelope the lower its abundance. A similar trend, albeit less clear than for SiO, is observed for SO in O-rich sources. The marked dependence of CS and SiS abundances on the C/O ratio indicates that these two molecules form more efficiently in C- than O-rich envelopes. The decline in the abundance of SiO with increasing envelope density and the tentative one for SO indicate that SiO and possibly SO act as gas-phase precursors of dust in circumstellar envelopes around O-rich AGB stars.
