Molecular spectroscopy prompted by astrophysical observations

1981 ◽  
Vol 303 (1480) ◽  
pp. 551-563 ◽  
Keyword(s):  
Molecular Spectroscopy ◽  
Far Infrared ◽  
Molecular Spectra ◽  
National Bureau ◽  
Millimetre Wave ◽  
The Galaxy ◽  
Wave Region ◽  
Simple Molecules ◽  
Basic Level ◽  
Maser Action

Observations of molecules in the Galaxy, whether by absorption, spontaneous emission or maser action, have shown that for all that molecular spectroscopy has long been studied in great detail, there are large gaps in our knowledge of even simple molecules, both in general and in detail. At the most basic level, a number of unidentified radio frequency lines were detected some while ago, and with the extension of observations into the millimetre wave region, many more unidentified lines have been found. Despite earlier extensive work at the National Bureau of Standards of the U. S. A, there remains a great need for measurements of frequencies of transitions in many molecules. The fact that galactic concentrations of molecules are often associated with strong sources of far infrared or ultraviolet radiation has shown that there are many gaps in our knowledge of molecular spectra in those technically difficult ranges of the spectrum and has led to attempts to develop improved techniques for studying them, as well as to interest in some theoretical problems.

scholarly journals Megamasers as probes of galaxy mass spectrum evolution

1991 ◽  
Vol 147 ◽  
pp. 440-440
Author(s):  
V.K. Khersonskii ◽  
N.V. Voshchinnikov
Keyword(s):  
Mass Spectrum ◽  
Spectral Line ◽  
Emission Line ◽  
Frequency Shift ◽  
Empirical Relation ◽  
Far Infrared ◽  
Merging Galaxies ◽  
Maser Emission ◽  
The Galaxy ◽  
Very High

OH megamasers having very high luminosities in the spectral line can be effectively used for the probing of the evolutionary properties of the galaxies in the earliest cosmological epochs. The frequency shift of the emission line uniqually determines the redshift z, which tells about the epoch of emission. One of the important cosmological problems is the investigation of the galaxy mass spectrum in the expanding Universe. There is the empirical relation between the OH and far-infrared luminosities of galaxies. Therefore, if in the earliest cosmological epochs, there were galaxies with sufficient powerful infrared excesses and containing molecular material, they can be detected using the observations of their OH maser emission. The interacting and merging galaxies can be considered as the best candidates for such objects.

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.

New far infrared observations of the central 30ʹ of the galaxy

1982 ◽  
Author(s):  
W. A. Dent ◽  
M. W. Werner ◽  
I. Gatley ◽  
E. E. Becklin ◽  
R. H. Hildebrand ◽  
...  
Keyword(s):  
Far Infrared ◽  
Infrared Observations ◽  
The Galaxy

scholarly journals Big Three Dragons: A [N ii] 122 μm Constraint and New Dust-continuum Detection of a z = 7.15 Bright Lyman-break Galaxy with ALMA

2021 ◽  
Vol 923 (1) ◽  
pp. 5
Author(s):  
Yuma Sugahara ◽  
Akio K. Inoue ◽  
Takuya Hashimoto ◽  
Satoshi Yamanaka ◽  
Seiji Fujimoto ◽  
...  
Keyword(s):  
Spectral Energy Distribution ◽  
Far Infrared ◽  
Abundance Ratio ◽  
Continuum Emission ◽  
Spectral Energy ◽  
High Ionization ◽  
The Galaxy ◽  
Infrared Spectral ◽  
Best Fit ◽  
Redshift Galaxies

Abstract We present new Atacama Large Millimeter/submillimeter Array Band 7 observational results of a Lyman-break galaxy at z = 7.15, B14-65666 (“Big Three Dragons”), which is an object detected in [O iii] 88 μm, [C ii] 158 μm, and dust continuum emission during the epoch of reionization. Our targets are the [N ii] 122 μm fine-structure emission line and the underlying 120 μm dust continuum. The dust continuum is detected with a ∼19σ significance. From far-infrared spectral energy distribution sampled at 90, 120, and 160 μm, we obtain a best-fit dust temperature of 40 K (79 K) and an infrared luminosity of log 10 ( L IR / L ⊙ ) = 11.6 (12.1) at the emissivity index β = 2.0 (1.0). The [N ii] 122 μm line is not detected. The 3σ upper limit of the [N ii] luminosity is 8.1 × 107 L ⊙. From the [N ii], [O iii], and [C ii] line luminosities, we use the Cloudy photoionization code to estimate nebular parameters as functions of metallicity. If the metallicity of the galaxy is high (Z > 0.4 Z ⊙), the ionization parameter and hydrogen density are log 10 U ≃ − 2.7 ± 0.1 and n H ≃ 50–250 cm−3, respectively, which are comparable to those measured in low-redshift galaxies. The nitrogen-to-oxygen abundance ratio, N/O, is constrained to be subsolar. At Z < 0.4 Z ⊙, the allowed U drastically increases as the assumed metallicity decreases. For high ionization parameters, the N/O constraint becomes weak. Finally, our Cloudy models predict the location of B14-65666 on the BPT diagram, thereby allowing a comparison with low-redshift galaxies.

scholarly journals Far-infrared estimates of the mass of gas in the Galaxy

1989 ◽  
Vol 237 (4) ◽  
pp. 1075-1084 ◽  
Author(s):  
A. Broadbent ◽  
I. MacLaren ◽  
A. W. Wolfendale
Keyword(s):  
Far Infrared ◽  
The Galaxy

scholarly journals 7.5. Tentative detection of far infrared excess in Arp 220

1998 ◽  
Vol 184 ◽  
pp. 301-302
Author(s):  
Kin-Wing Chan ◽  
S. H. Moseley ◽  
E. Dwek ◽  
T. L. Roellig ◽  
S. Casey ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Time Scale ◽  
Far Infrared ◽  
Infrared Emission ◽  
Short Time Scale ◽  
Active Nucleus ◽  
Infrared Excess ◽  
Grating Spectrometer ◽  
The Galaxy ◽  
Short Time

We report 36 to 50 μm observations of Arp 220 by the Goddard Cryogenic Grating Spectrometer on the Kuiper Airborne Observatory in May 1994. In this measurement, we find the galaxy to be four times brighter than in the measurements of Joy et al. (1986). If both of the observations are correct, this large far infrared luminosity increasing in a short time scale between the two observations suggests that the infrared emission in Arp 220 consists mostly of nonthermal synchrotron radiation which originates from the active nucleus.

scholarly journals Rapid evolution and transformation into quiescence?: ALMA view on z > 6 low-luminosity quasars

2019 ◽  
Vol 15 (S352) ◽  
pp. 139-143
Author(s):  
Takuma Izumi ◽  
Masafusa Onoue ◽  
Yoshiki Matsuoka ◽  
Tohru Nagao ◽  
Michael A. Strauss ◽  
...  
Keyword(s):  
Black Holes ◽  
Mass Distribution ◽  
Rapid Evolution ◽  
Far Infrared ◽  
Significant Fraction ◽  
Host Galaxies ◽  
Dynamical Mass ◽  
The Galaxy ◽  
Order Of Magnitude ◽  
Wide Scatter

AbstractWe present ALMA [CII] line and far-infrared (FIR) continuum observations of seven z > 6 low-luminosity quasars (M1450 > −25 mag) discovered by our on-going Subaru Hyper Suprime-Cam survey. The [CII] line was detected in all targets with luminosities of ∼(2−10) × 108 L⊙, about one order of magnitude smaller than optically luminous quasars. Also found was a wide scatter of FIR continuum luminosity, ranging from LFIR < 1011L⊙ to ∼2 × 1012L⊙. With the [CII]-based dynamical mass, we suggest that a significant fraction of low-luminosity quasars are located on or even below the local Magorrian relation, particularly at the massive end of the galaxy mass distribution. This is a clear contrast to the previous finding that luminous quasars tend to have overmassive black holes relative to the relation. Our result is expected to show a less-biased nature of the early co-evolution of black holes and their host galaxies.

Far-infrared lines from H II regions: Abundance variations in the galaxy

1995 ◽  
Vol 444 ◽  
pp. 721 ◽  
Author(s):  
Janet P. Simpson ◽  
Sean W. J. Colgan ◽  
Robert H. Rubin ◽  
Edwin F. Erickson ◽  
Michael R. Haas
Keyword(s):  
Far Infrared ◽  
H Ii Regions ◽  
The Galaxy

scholarly journals Giant Molecular Clouds in the Galaxy: The Massachusetts-Stony Brook CO Galactic Plane Survey

1987 ◽  
Vol 115 ◽  
pp. 499-499 ◽  
Author(s):  
P. M. Solomon
Keyword(s):  
Molecular Clouds ◽  
Galactic Plane ◽  
Far Infrared ◽  
Formation Mechanisms ◽  
H Ii Regions ◽  
Giant Molecular Clouds ◽  
Star Forming ◽  
The Galaxy ◽  
Two Populations ◽  
Spiral Arm

The CO Galactic Plane Survey consists of 40,572 spectral line observations in the region between 1 = 8° to 90° and b = −1°.05 to +1°.05 spaced every 3 arc minutes, carried out with the FCRAO 14-m antenna. The velocity coverage from −100 to +200 km/s includes emission from all galactic radii. This high resolution survey was designed to observe and identify essentially all molecular clouds or cloud components larger than 10 parsecs in the inner galaxy. There are two populations of molecular clouds which separate according to temperature. The warm clouds are closely associated with H II regions, exhibit a non-axisymmetric galactic distribution and are a spiral arm population. The cold clouds are a disk population, are not confined to any patterns in longitude-velocity space and must be widespread in the galaxy both in and out of spiral arms. The correlation between far infrared luminosities from IRAS, and molecular masses from CO is utilized to determine a luminosity to mass ratio for the clouds. A face-on picture of the galaxy locating the warm population is presented, showing ring like or spiral arm features at R ∼ 5, 7.5 and 9 kpc. The cloud size and mass spectrum will be discussed and evidence presented showing the presence of clusters of giant molecular clouds with masses of 106 to 107 M⊙. The two populations of clouds probably have different star forming luminosity functions. The implication of the two populations for star formation mechanisms will be discussed.

scholarly journals Hidden or missing outflows in highly obscured galaxy nuclei?

2019 ◽  
Vol 623 ◽  
pp. A29 ◽  
Author(s):  
N. Falstad ◽  
F. Hallqvist ◽  
S. Aalto ◽  
S. König ◽  
S. Muller ◽  
...  
Keyword(s):  
Line Emission ◽  
Far Infrared ◽  
Spectral Lines ◽  
Absorption Lines ◽  
Wide Angle ◽  
Vibrationally Excited ◽  
Molecular Outflows ◽  
Luminous Infrared Galaxies ◽  
The Galaxy ◽  
Central Regions

Context. Understanding the nuclear growth and feedback processes in galaxies requires investigating their often obscured central regions. One way to do this is to use (sub)millimeter line emission from vibrationally excited HCN (HCN-vib), which is thought to trace warm and highly enshrouded galaxy nuclei. It has been suggested that the most intense HCN-vib emission from a galaxy is connected to a phase of nuclear growth that occurs before the nuclear feedback processes have been fully developed. Aims. We aim to investigate if there is a connection between the presence of strong HCN-vib emission and the development of feedback in (ultra)luminous infrared galaxies ((U)LIRGs). Methods. We collected literature and archival data to compare the luminosities of rotational lines of HCN-vib, normalized to the total infrared luminosity, to the median velocities of 119 μm OH absorption lines, potentially indicating outflows, in a total of 17 (U)LIRGs. Results. The most HCN-vib luminous systems all lack signatures of significant molecular outflows in the far-infrared OH absorption lines. However, at least some of the systems with bright HCN-vib emission have fast and collimated outflows that can be seen in spectral lines at longer wavelengths, including in millimeter emission lines of CO and HCN (in its vibrational ground state) and in radio absorption lines of OH. Conclusions. We conclude that the galaxy nuclei with the highest LHCN − vib/LIR do not drive wide-angle outflows that are detectable using the median velocities of far-infrared OH absorption lines. This is possibly because of an orientation effect in which sources oriented in such a way that their outflows are not along our line of sight also radiate a smaller proportion of their infrared luminosity in our direction. It could also be that massive wide-angle outflows destroy the deeply embedded regions responsible for bright HCN-vib emission, so that the two phenomena cannot coexist. This would strengthen the idea that vibrationally excited HCN traces a heavily obscured stage of evolution before nuclear feedback mechanisms are fully developed.

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