Far-infrared emission in the Rho Ophiuchi region - A comparison with molecular gas emission and visual extinction

1989 ◽  
Vol 345 ◽  
pp. 881 ◽  
Author(s):  
T. H. Jarrett ◽  
R. L. Dickman ◽  
W. Herbst
Keyword(s):  
Far Infrared ◽  
Infrared Emission ◽  
Molecular Gas ◽  
Gas Emission ◽  
Visual Extinction ◽  
Rho Ophiuchi

scholarly journals Dense Molecular Gas at High Redshift: First Detection of Emission from HCO+

2006 ◽  
Vol 2 (S235) ◽  
pp. 424-424
Author(s):  
D.A. Riechers ◽  
F. Walter ◽  
C.L. Carilli ◽  
A. Weiss ◽  
F. Bertoldi ◽  
...  
Keyword(s):  
Molecular Hydrogen ◽  
Molecular Clouds ◽  
High Redshift ◽  
Far Infrared ◽  
Hydrogen Gas ◽  
Molecular Gas ◽  
Gas Emission ◽  
Very Large Array ◽  
Star Forming ◽  
Good Tracer

AbstractUsing the Very Large Array (VLA), we have detected the HCO+(1–0) emission line towards the Cloverleaf quasar (z = 2.56; Riechers et al. 2006). This is the first detection of ionized molecular gas emission at high redshift (z>2). HCO+ emission is a star formation indicator similar to HCN, tracing dense molecular hydrogen gas within star-forming molecular clouds. We find a HCO+/CO luminosity ratio of 0.08 and a HCO+/HCN luminosity ratio of 0.8 for the Cloverleaf. These ratios fall within the scatter of the same relationships found for low–z star–forming galaxies. However, a HCO+/HCN luminosity ratio close to unity would not be expected for the Cloverleaf if the recently suggested relation between this ratio and the far–infrared luminosity (Graciá–Carpio et al. 2006) were to hold. We conclude that a ratio between HCO+ and HCN luminosity close to 1 is likely due to the fact that the emission from both lines is optically thick and thermalized and emerges from dense regions of similar volumes. We conclude that HCO+ is potentially a good tracer for dense molecular gas at high redshift.

Molecular gas mass and far-infrared emission from distant luminous galaxies

1993 ◽  
Vol 414 ◽  
pp. L13 ◽  
Author(s):  
D. Downes ◽  
P. M. Solomon ◽  
S. J. E. Radford
Keyword(s):  
Far Infrared ◽  
Infrared Emission ◽  
Molecular Gas ◽  
Luminous Galaxies

scholarly journals Studying the Atomic and Molecular Hydrogen Mass (MHI, MH2) Properties of the Extragalactic Spectra

2020 ◽  
pp. 1233-1243
Author(s):  
M. N. Al Najm
Keyword(s):  
Star Formation ◽  
Molecular Hydrogen ◽  
Partial Correlation ◽  
Far Infrared ◽  
Infrared Emission ◽  
Molecular Gas ◽  
Strongly Correlated ◽  
Hydrogen Mass ◽  
Formation Efficiency ◽  
Cold Gas

The purpose of this study is to deal with dust and interstellar molecular and atomic gas owing to obtaining a proportion of cold gas to dust and to understand the characteristics of the molecular gas in extragalactic data selected from the Herschel SPIRE/ FTS archive. The physical properties of a sample of 65 extragalactic spectra characterized by the activity of star formation were discussed in this work. Statistical analyses, using STATISTICA program, were made for the content of cold gas (MHI, MH2), dust mass (Mdust), cold temperature of dust (Td) and luminosities in Far-infrared to CO line radiations, while coefficients of partial correlation within those characteristics were established. The results showed that the molecular hydrogen mass (MH2) is strongly correlated with the HI or the total gas mass corresponding to the Far-infrared emission (LFIR) resulting from dust in the galaxies molecular clouds. The results also indicated that these kinds of galaxies have large molecular mass as well as high star formation efficiency per unit mass.

scholarly journals Galactic Far-Infrared Diffuse Emission

2001 ◽  
Vol 204 ◽  
pp. 47-55
Author(s):  
François Boulanger ◽  
Jean-Philippe Bernard ◽  
Guilaine Lagache ◽  
Bertrand Stepnik
Keyword(s):  
Interstellar Dust ◽  
Spectral Energy Distribution ◽  
Dust Emission ◽  
Far Infrared ◽  
Spectral Energy ◽  
Molecular Gas ◽  
Diffuse Emission ◽  
Gas Emission ◽  
Present Understanding ◽  
Small Dust

We review the present understanding of the interstellar dust contribution to the far-IR (λ > 100 μm) sky emission. We show how the contribution from the distinct ISM components (HI, H2, HII gas) are identified and characterized through spatial correlation with gas emission lines. We discuss the spectral energy distribution of the emission from cirrus dust associated with diffuse HI gas and from colder dust associated with molecular gas. We relate the drop in dust emission temperature from the diffuse interstellar medium to molecular gas to an evolution of dust affecting both the abundance of small dust grains and the far-IR emissivity of large grains.

Searches for far-infrared emission from dark clouds - Rho Ophiuchi, Heiles 2, L1529, and L183

1983 ◽  
Vol 88 ◽  
pp. 88 ◽  
Author(s):  
A. I. Sargent ◽  
R. J. van Duinen ◽  
H. L. Nordh ◽  
C. V. M. Fridlund ◽  
J. W. G. Aalders ◽  
...  
Keyword(s):  
Far Infrared ◽  
Infrared Emission ◽  
Dark Clouds ◽  
Rho Ophiuchi

5.21. Molecular gas in the center of the elliptical galaxy NGC759

1998 ◽  
Vol 184 ◽  
pp. 253-254
Author(s):  
T. Wiklind ◽  
F. Combes ◽  
C. Henkel ◽  
F. Wyrowski
Keyword(s):  
Star Formation ◽  
Uv Light ◽  
Elliptical Galaxy ◽  
Large Fraction ◽  
Dust Emission ◽  
Far Infrared ◽  
Elliptical Galaxies ◽  
Infrared Emission ◽  
Continuum Emission ◽  
Molecular Gas

Elliptical galaxies are traditionally defined as gas–free, inert stellar systems. Observations of continuum emission in the far–infrared (FIR) and sub–mm wavelength bands have, however, shown that a large fraction of all ellipticals, ~50% (Jura et al. 1987), contain a dust component. The infrared emission is due to warm dust, in many cases associated with star formation and/or weak AGN activity, while cold dust dominates the long wavelength continuum emission (e.g. Wiklind & Henkel 1995). Some elliptical galaxies also contain a molecular gas component, as seen through CO emission (Lees et al. 1991; Wiklind et al. 1995; Knapp & Rupen 1996). The dust and molecular gas are believed to be associated with each other, but it is not clear what powers the emission: star formation activity and/or AGN activity. Both the molecular gas mass and the FIR luminosity are on average lower in ellipticals than in spiral galaxies of similar luminosities. However, the LFIR/MH2 ratio is larger for the elliptical galaxies. If this ratio is a measure of the star formation efficiency, this suggests that gas is being used up more efficiently in elliptical galaxies than in normal spirals (e.g. Wiklind et al. 1995). Other possibilities is that the FIR dust emission is not only powered by UV–light from young stars, but from other sources as well, or that some dust is not spatially associated with the molecular gas.

Far infrared emission from magnetically quantised 2DEGs in GaAs/(AlGa)As heterojunctions

1994 ◽  
Vol 305 (1-3) ◽  
pp. 280-284 ◽  
Author(s):  
N.N. Zinov'ev ◽  
R. Fletcher ◽  
L.J. Challis ◽  
B. Sujak-Cyrul ◽  
A.V. Akimov ◽  
...  
Keyword(s):  
Far Infrared ◽  
Infrared Emission

scholarly journals Hidden molecular outflow in the LIRG Zw 049.057

2018 ◽  
Vol 609 ◽  
pp. A75 ◽  
Author(s):  
N. Falstad ◽  
S. Aalto ◽  
J. G. Mangum ◽  
F. Costagliola ◽  
J. S. Gallagher ◽  
...  
Keyword(s):  
Far Infrared ◽  
Minor Axis ◽  
Spectral Lines ◽  
Continuum Emission ◽  
High Angular Resolution ◽  
Molecular Gas ◽  
Nuclear Activity ◽  
Molecular Outflow ◽  
The Galaxy ◽  
Excitation Conditions

Context. Feedback in the form of mass outflows driven by star formation or active galactic nuclei is a key component of galaxy evolution. The luminous infrared galaxy Zw 049.057 harbours a compact obscured nucleus with a possible far-infrared signature of outflowing molecular gas. Due to the high optical depths at far-infrared wavelengths, however, the interpretation of the outflow signature is uncertain. At millimeter and radio wavelengths, the radiation is better able to penetrate the large columns of gas and dust responsible for the obscuration. Aims. We aim to investigate the molecular gas distribution and kinematics in the nucleus of Zw 049.057 in order to confirm and locate the molecular outflow, with the ultimate goal to understand how the nuclear activity affects the host galaxy. Methods. We used high angular resolution observations from the Submillimeter Array (SMA), the Atacama Large Millimeter/submillimeter Array (ALMA), and the Karl G. Jansky Very Large Array (VLA) to image the CO J = 2–1 and J = 6–5 emission, the 690 GHz continuum, the radio centimeter continuum, and absorptions by rotationally excited OH. Results. The CO line profiles exhibit wings extending ~ 300 km s-1 beyond the systemic velocity. At centimeter wavelengths, we find a compact (~ 40 pc) continuum component in the nucleus, with weaker emission extending several 100 pc approximately along the major and minor axes of the galaxy. In the OH absorption lines toward the compact continuum, wings extending to a similar velocity as for the CO are only seen on the blue side of the profile. The weak centimeter continuum emission along the minor axis is aligned with a highly collimated, jet-like dust feature previously seen in near-infrared images of the galaxy. Comparison of the apparent optical depths in the OH lines indicate that the excitation conditions in Zw 049.057 differ from those within other OH megamaser galaxies. Conclusions. We interpret the wings in the spectral lines as signatures of a nuclear molecular outflow. A relation between this outflow and the minor axis radio feature is possible, although further studies are required to investigate this possible association and understand the connection between the outflow and the nuclear activity. Finally, we suggest that the differing OH excitation conditions are further evidence that Zw 049.057 is in a transition phase between megamaser and kilomaser activity.

scholarly journals Molecular gas in the Herschel-selected strongly lensed submillimeter galaxies at z ~ 2–4 as probed by multi-J CO lines

2017 ◽  
Vol 608 ◽  
pp. A144 ◽  
Author(s):  
C. Yang ◽  
A. Omont ◽  
A. Beelen ◽  
Y. Gao ◽  
P. van der Werf ◽  
...  
Keyword(s):  
Star Formation ◽  
High Redshift ◽  
Line Emission ◽  
Far Infrared ◽  
Molecular Gas ◽  
Kinetic Temperature ◽  
Large Area ◽  
Line Energy ◽  
Submillimeter Galaxies ◽  
Dust Mass

We present the IRAM-30 m observations of multiple-J CO (Jup mostly from 3 up to 8) and [C I](3P2 → 3P1) ([C I](2–1) hereafter) line emission in a sample of redshift ~2–4 submillimeter galaxies (SMGs). These SMGs are selected among the brightest-lensed galaxies discovered in the Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS). Forty-seven CO lines and 7 [C I](2–1) lines have been detected in 15 lensed SMGs. A non-negligible effect of differential lensing is found for the CO emission lines, which could have caused significant underestimations of the linewidths, and hence of the dynamical masses. The CO spectral line energy distributions (SLEDs), peaking around Jup ~ 5–7, are found to be similar to those of the local starburst-dominated ultra-luminous infrared galaxies and of the previously studied SMGs. After correcting for lensing amplification, we derived the global properties of the bulk of molecular gas in the SMGs using non-LTE radiative transfer modelling, such as the molecular gas density nH2 ~ 102.5–104.1 cm-3 and the kinetic temperature Tk  ~ 20–750 K. The gas thermal pressure Pth ranging from~105 K cm-3 to 106 K cm-3 is found to be correlated with star formation efficiency. Further decomposing the CO SLEDs into two excitation components, we find a low-excitation component with nH2 ~ 102.8–104.6 cm-3 and Tk  ~ 20–30 K, which is less correlated with star formation, and a high-excitation one (nH2 ~ 102.7–104.2 cm-3, Tk  ~ 60–400 K) which is tightly related to the on-going star-forming activity. Additionally, tight linear correlations between the far-infrared and CO line luminosities have been confirmed for the Jup ≥ 5 CO lines of these SMGs, implying that these CO lines are good tracers of star formation. The [C I](2–1) lines follow the tight linear correlation between the luminosities of the [C I](2–1) and the CO(1–0) line found in local starbursts, indicating that [C I] lines could serve as good total molecular gas mass tracers for high-redshift SMGs as well. The total mass of the molecular gas reservoir, (1–30) × 1010M⊙, derived based on the CO(3–2) fluxes and αCO(1–0) = 0.8 M⊙ ( K km s-1 pc2)-1, suggests a typical molecular gas depletion time tdep ~ 20–100 Myr and a gas to dust mass ratio δGDR ~ 30–100 with ~20%–60% uncertainty for the SMGs. The ratio between CO line luminosity and the dust mass L′CO/Mdust appears to be slowly increasing with redshift for high-redshift SMGs, which need to be further confirmed by a more complete SMG sample at various redshifts. Finally, through comparing the linewidth of CO and H2O lines, we find that they agree well in almost all our SMGs, confirming that the emitting regions of the CO and H2O lines are co-spatially located.

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