Detection of HCO(+) J = 9 - 8 line emission toward Orion IRc2 - Molecular ions in hot dense gas

1992 ◽  
Vol 385 ◽  
pp. 240 ◽  
Author(s):  
D. T. Jaffe ◽  
U. U. Graf ◽  
A. I. Harris ◽  
J. Stutzki ◽  
S. H. Lepp
Keyword(s):  
Line Emission ◽  
Molecular Ions ◽  
Dense Gas

scholarly journals INVESTIGATION OF DENSE GAS TOWARDS RELATIVISTIC OUTFLOW SOURCES

2014 ◽  
Vol 28 ◽  
pp. 1460198
Author(s):  
J. HAWKES ◽  
G. ROWELL ◽  
B. DAWSON ◽  
F. AHARONIAN ◽  
M. BURTON ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Line Emission ◽  
High Energy ◽  
Dense Gas ◽  
Relativistic Jets ◽  
Hii Region ◽  
X Ray ◽  
Stellar Cluster ◽  
Radio Recombination Line ◽  
Low Mass

We probe the interstellar medium towards the objects Circinus X-1, a low-mass X-ray binary with relativistic jets; and the highly energetic Westerlund 2 stellar cluster, which is located towards TeV gamma-ray emission and interesting arc- and jet-like features seen in Nanten 12CO data. We have mapped both regions with the Mopra radio telescope, in 7 mm and 12 mm wavebands, looking for evidence of disrupted/dense gas caused by the interaction between high energy outflows and the ISM. Towards Westerlund 2, peaks in CS(J=1-0) emission indicate high density gas towards the middle of the arc and the endpoint of the jet; and radio recombination line emission is seen overlapping the coincident HII region RCW49. Towards Circinus X-1, 12CO(J = 1-0) Nanten data reveals three molecular clouds that lie in the region of Cir X-1. Gas parameters for each cloud are presented here.

scholarly journals ALMA Explorations of Warm Dense Molecular Gas in Nearby LIRGs

2014 ◽  
Vol 10 (S309) ◽  
pp. 61-64
Author(s):  
C. Kevin Xu
Keyword(s):  
Line Emission ◽  
Continuum Emission ◽  
Molecular Gas ◽  
Dense Gas ◽  
Strongly Coupled ◽  
Luminous Infrared Galaxies ◽  
Physical Conditions ◽  
Major Merger ◽  
A Minor ◽  
Tight Correlation

AbstractWe present results of ALMA (Cycle-0) observations of the CO (6-5) line emission and the 435μm continuum of two nearby luminous infrared galaxies (LIRGs) NGC 34 (a major merger with an AGN) and NGC 1614 (a minor merger with a circum-nuclear starburst). Using receivers in the highest frequency ALMA band available (Band-9), these observations achieved the best angular resolutions (∼0″.25) for ALMA Cycle-0 observations and resolved for the first time distributions of warm dense molecular gas (n > 105 cm−3, T > 100 K) in LIRGs with spatial resolutions better than 100 pc. Our ALMA data show a very tight correlation between the CO (6-5) line emission and the 435μm dust continuum emission, suggesting the warm dense molecular gas dominates the ISM in the central kpc of LIRGs, and gas heating and dust heating in the warm dense gas cores are strongly coupled. On the other hand, we saw very different spatial distributions and kinematic properties of warm dense gas in the two LIRGs, indicating that physical conditions in the ISM can be very different in different LIRGs.

scholarly journals ATOMS: ALMA three-millimeter observations of massive star-forming regions – II. Compact objects in ACA observations and star formation scaling relations

2020 ◽  
Vol 496 (3) ◽  
pp. 2821-2835 ◽  
Author(s):  
Tie Liu ◽  
Neal J Evans ◽  
Kee-Tae Kim ◽  
Paul F Goldsmith ◽  
Sheng-Yuan Liu ◽  
...  
Keyword(s):  
Star Formation ◽  
Spatial Scales ◽  
Line Emission ◽  
Compact Objects ◽  
Dense Gas ◽  
Molecular Line ◽  
Star Forming ◽  
Bolometric Luminosity ◽  
Star Forming Regions ◽  
Formation Efficiency

ABSTRACT We report studies of the relationships between the total bolometric luminosity (Lbol or LTIR) and the molecular line luminosities of J = 1 − 0 transitions of H13CN, H13CO+, HCN, and HCO+ with data obtained from ACA observations in the ‘ATOMS’ survey of 146 active Galactic star-forming regions. The correlations between Lbol and molecular line luminosities $L^{\prime }_{\rm mol}$ of the four transitions all appear to be approximately linear. Line emission of isotopologues shows as large scatters in Lbol–$L^{\prime }_{\rm mol}$ relations as their main line emission. The log(Lbol/$L^{\prime }_{\rm mol}$) for different molecular line tracers have similar distributions. The Lbol-to-$L^{\prime }_{\rm mol}$ ratios do not change with galactocentric distances (RGC) and clump masses (Mclump). The molecular line luminosity ratios (HCN-to-HCO+, H13CN-to-H13CO+, HCN-to-H13CN, and HCO+-to-H13CO+) all appear constant against Lbol, dust temperature (Td), Mclump, and RGC. Our studies suggest that both the main lines and isotopologue lines are good tracers of the total masses of dense gas in Galactic molecular clumps. The large optical depths of main lines do not affect the interpretation of the slopes in star formation relations. We find that the mean star formation efficiency (SFE) of massive Galactic clumps in the ‘ATOMS’ survey is reasonably consistent with other measures of the SFE for dense gas, even those using very different tracers or examining very different spatial scales.

Ionic recombination of rare‐gas molecular ions X+2 with F− in a dense gas X

1978 ◽  
Vol 32 (6) ◽  
pp. 356-357 ◽  
Author(s):  
M. R. Flannery ◽  
T. P. Yang
Keyword(s):  
Molecular Ions ◽  
Rare Gas ◽  
Dense Gas

scholarly journals Sgr A West in the light of molecules: cold and dense gas east of the circumnuclear disk

2013 ◽  
Vol 9 (S303) ◽  
pp. 86-88 ◽  
Author(s):  
Lydia Moser ◽  
A. Eckart ◽  
A. Borkar ◽  
M. García-Marin ◽  
D. Kunneriath ◽  
...  
Keyword(s):  
Black Hole ◽  
Star Formation ◽  
Molecular Clouds ◽  
Near Infrared ◽  
Line Emission ◽  
Dense Gas ◽  
Dark Clouds ◽  
Supermassive Black Hole ◽  
Circumnuclear Disk ◽  
Sgr A

AbstractWe present the very first detection of N2H+J = (1 – 0) and CH3OH(2k−1k) line emission on 5″ scales in the circumnuclear disk (CND) around Sgr A*. The emission matches the position and shape of the dark clouds in the near-infrared. Our findings suggest that these molecular clouds in the eastern CND are significantly colder and denser than the rest of the CND, and partially shocked. The research on these dark clouds will contribute to understanding the processes of star formation close to a supermassive black hole.

scholarly journals Planck’s Dusty GEMS

2021 ◽  
Vol 645 ◽  
pp. A45
Author(s):  
R. Cañameras ◽  
N. P. H. Nesvadba ◽  
R. Kneissl ◽  
S. König ◽  
C. Yang ◽  
...  
Keyword(s):  
Star Formation ◽  
High Redshift ◽  
Line Emission ◽  
Flux Ratio ◽  
Theoretical Models ◽  
High Density ◽  
Line Profiles ◽  
Dense Gas ◽  
Gas Reservoirs ◽  
Star Forming

We present ALMA, NOEMA, and IRAM-30 m/EMIR observations of the high-density tracer molecules HCN, HCO+, and HNC in three of the brightest lensed dusty star-forming galaxies at z ≃ 3–3.5, part of the Planck’s Dusty Gravitationally Enhanced subMillimetre Sources (GEMS), with the aim of probing the gas reservoirs closely associated with their exceptional levels of star formation. We obtained robust detections of ten emission lines between Jup = 4 and 6, as well as several additional upper flux limits. In PLCK_G244.8+54.9, the brightest source at z = 3.0, the HNC(5–4) line emission at 0.1″ resolution, together with other spatially-integrated line profiles, suggests comparable distributions of dense and more diffuse gas reservoirs, at least over the most strongly magnified regions. This rules out any major effect from differential lensing. This line is blended with CN(4–3) and in this source, we measure a HNC(5–4)/CN(4–3) flux ratio of 1.76 ±0. 86. Dense-gas line profiles generally match those of mid-J CO lines, except in PLCK_G145.2+50.8, which also has dense-gas line fluxes that are relatively lower, perhaps due to fewer dense cores and more segregated dense and diffuse gas phases in this source. The HCO+/HCN ≳ 1 and HNC/HCN ∼ 1 line ratios in our sample are similar to those of nearby ultraluminous infrared galaxies (ULIRGs) and consistent with photon-dominated regions without any indication of important mechanical heating or active galactic nuclei feedback. We characterize the dense-gas excitation in PLCK_G244.8+54.9 using radiative transfer models assuming pure collisional excitation and find that mid-J HCN, HCO+, and HNC lines arise from a high-density phase with an H2 density of n  ∼  105–106 cm−3, although important degeneracies hinder a determination of the exact conditions. The three GEMS are consistent with extrapolations of dense-gas star-formation laws derived in the nearby Universe, adding further evidence that the extreme star-formation rates observed in the most active galaxies at z ∼ 3 are a consequence of their important dense-gas contents. The dense-gas-mass fractions traced by HCN/[CI] and HCO+/[CI] line ratios are elevated, but not exceptional as compared to other lensed dusty star-forming galaxies at z >  2, and they fall near the upper envelope of local ULIRGs. Despite the higher overall gas fractions and local gas-mass surface densities observed at high redshift, the dense-gas budget of rapidly star-forming galaxies seems to have evolved little between z ∼ 3 and z ∼ 0. Our results favor constant dense-gas depletion times in these populations, which is in agreement with theoretical models of star formation.

scholarly journals COOLING OF DENSE GAS BY H2O LINE EMISSION AND AN ASSESSMENT OF ITS EFFECTS IN CHONDRULE-FORMING SHOCKS

2009 ◽  
Vol 691 (1) ◽  
pp. 320-331 ◽  
Author(s):  
M. A. Morris ◽  
S. J. Desch ◽  
F. J. Ciesla
Keyword(s):  
Line Emission ◽  
Dense Gas

scholarly journals The Contribution of Čerenkov Line Radiation to the Broad Lines in AGNs

1997 ◽  
Vol 159 ◽  
pp. 224-227
Author(s):  
Hao Wu ◽  
Jian-rong Shi ◽  
Jun-han You
Keyword(s):  
Emission Line ◽  
Recent Progress ◽  
Line Emission ◽  
Emission Lines ◽  
Relativistic Electrons ◽  
Emission Model ◽  
Apparent Velocity ◽  
Dense Gas ◽  
Line Radiation ◽  
Gas Medium

In 1980, You & Cheng (1980) suggested that in a dense gas medium, relativistic electrons will produce Čerenkov atomic or molecular emission lines of widths Δλ ≈ 1 – 10Å. The Čerenkov line is broader than a normal emission line and has small redshift (ΔZc ≡ Δλp/λlu ≈ 10–3), so the apparent velocity is about a few hundred km s−1. We refer to this as the ‘Čerenkov redshift’. In 1986, You & Cheng gave simplified formulae for Čerenkov line emission and the mechanism was confirmed by a series of elegant experiments (Xu et al. 1988, 1989). Recent progress in studies of AGNs, both in theory and observation, provide support for the Čerenkov line-emission model of the BLR of AGNs. In this paper, we prove that for a dense gas, if there are enough relativistic electrons, the Čerenkov line emission is strong enough to compare with the observations, and the Čerenkov line emission dominates over the spontaneous emission lines in the optically thick case.

scholarly journals HCN 3–2 survey towards a sample of local galaxies

2020 ◽  
Vol 72 (3) ◽  
Author(s):  
Fei Li ◽  
Junzhi Wang ◽  
Min Fang ◽  
Qing-Hua Tan ◽  
Zhi-Yu Zhang ◽  
...  
Keyword(s):  
Correlation Coefficient ◽  
Linear Correlation ◽  
Line Emission ◽  
Volume Density ◽  
Molecular Gas ◽  
Dense Gas ◽  
Large Scatter ◽  
Similar Relation ◽  
Density Threshold ◽  
Individual Galaxies

Abstract We present observations of HCN 3–2 emissions towards 37 local galaxies using the 10 m Submillimeter Telescope. HCN 3–2 emission is detected in 23 galaxies. The correlation of infrared luminosity (LIR) and the luminosity of HCN 3–2 line emission measured in our sample is fitted with a slope of 1.11 and correlation coefficient of 0.91, which follows the linear correlation found in other dense gas tracers in the literature. Although molecular gas above a certain volume density threshold (i.e., $n_{\rm H_2}\ge 10^4\:$cm−3) statistically gave a similar relation with infrared luminosity, the large scatter of HCN 3–2/HCN 1–0 ratios for galaxies with different LIR indicates that dense gas masses estimated from the line luminosities of only one transition of dense gas tracers should be treated with caution for individual galaxies.

A New Probe of Dense Gas at High Redshift: Detection of HCO + (5-4) Line Emission in APM 08279+5255

2006 ◽  
Vol 645 (1) ◽  
pp. L17-L20 ◽  
Author(s):  
S. García-Burillo ◽  
J. Graciá-Carpio ◽  
M. Guélin ◽  
R. Neri ◽  
P. Cox ◽  
...  
Keyword(s):  
High Redshift ◽  
Line Emission ◽  
Dense Gas
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