scholarly journals A 3-mm molecular line study of the Central Molecular Zone of the Galaxy

2008 ◽  
Vol 4 (S251) ◽  
pp. 257-262
Author(s):  
Paul A. Jones ◽  
Michael G. Burton ◽  
Vicki Lowe
Keyword(s):  
Principal Component Analysis ◽  
Principal Component ◽  
Galactic Centre ◽  
Frequency Range ◽  
Molecular Line ◽  
Physical Conditions ◽  
The Galaxy ◽  
Molecular Lines ◽  
Sgr A ◽  
Cloud Complex

AbstractWe are studying the Central Molecular Zone (CMZ) in the inner few degrees around the Galactic Centre, by mapping multiple 3-mm molecular lines, with the 22-m Mopra telescope. During 2006, we covered a 5 × 5 arcmin2 area of the Sagittarius B2 molecular cloud complex (Jones et al. 2008). We find substantial differences in chemical and physical conditions within the complex. We show some results here of Principal Component Analysis (PCA) of line features in this Sgr B2 area. During 2007 we covered the larger region of longitude −0.2 to 0.9 deg. and latitude -0.20 to 0.12 deg., including Sgr A and Sgr B2, in the frequency range 85.3 to 91.3 GHz. This includes lines of C3H2, CH3CCH, HOCO+, SO, H13CN, H13CO+, SO, H13NC, C2H, HNCO, HCN, HCO+, HNC, HC3N, 13CS and N2H+.

scholarly journals Molecular Distributions of the Disk/Envelope System of L483: Principal Component Analysis for the Image Cube Data

2021 ◽  
Vol 923 (2) ◽  
pp. 168
Author(s):  
Yuki Okoda ◽  
Yoko Oya ◽  
Shotaro Abe ◽  
Ayano Komaki ◽  
Yoshimasa Watanabe ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Principal Component ◽  
Component Analysis ◽  
Molecular Line ◽  
Large Correlation ◽  
Complex Organic Molecule ◽  
Molecular Lines ◽  
Characteristic Features ◽  
The Moment ◽  
Complex Organic

Abstract Unbiased understanding of molecular distributions in a disk/envelope system of a low-mass protostellar source is crucial for investigating physical and chemical evolution processes. We have observed 23 molecular lines toward the Class 0 protostellar source L483 with ALMA and have performed principal component analysis (PCA) for their cube data (PCA-3D) to characterize their distributions and velocity structures in the vicinity of the protostar. The sum of the contributions of the first three components is 63.1%. Most oxygen-bearing complex organic molecule lines have a large correlation with the first principal component (PC1), representing the overall structure of the disk/envelope system around the protostar. Contrary, the C18O and SiO emissions show small and negative correlations with PC1. The NH2CHO lines stand out conspicuously at the second principal component (PC2), revealing more compact distribution. The HNCO lines and the high-excitation line of CH3OH have a similar trend for PC2 to NH2CHO. On the other hand, C18O is well correlated with the third principal component (PC3). Thus, PCA-3D enables us to elucidate the similarities and the differences of the distributions and the velocity structures among molecular lines simultaneously, so that the chemical differentiation between the oxygen-bearing complex organic molecules and the nitrogen-bearing ones is revealed in this source. We have also conducted PCA for the moment 0 maps (PCA-2D) and that for the spectral line profiles (PCA-1D). While they can extract part of characteristics of the molecular line data, PCA-3D is essential for comprehensive understandings. Characteristic features of the molecular line distributions are discussed on NH2CHO.

scholarly journals Massive Star Formation in W49

1987 ◽  
Vol 115 ◽  
pp. 143-145
Author(s):  
J. Dreher ◽  
S. Vogel ◽  
S. Terebey ◽  
W. J. Welch
Keyword(s):  
Star Formation ◽  
High Resolution ◽  
Massive Star ◽  
Hii Regions ◽  
Molecular Line ◽  
The Galaxy ◽  
Molecular Lines ◽  
H Ii Region ◽  
Scale Structures ◽  
The Continuum

W49 is the most luminous H II region complex in the galaxy. VLA maps in the continuum reveal a complex of more than two dozen compact HII regions, including a ring-like distribution of a dozen such regions within a volume of 1 pc. In addition to the VLA maps, we have obtained high resolution maps in this field with the Hat Creek Millimeter Interferometer in the following molecular lines: HCO+(1-0), H13CO+(1-0), SiO(v = 0, J = 2-1), SiO(v = 1, J = 2-1), H13CN(1-0), HC15N(1-0), SO2 [8(3,5)-9(2,8)], SO2[8(1,7)-8(0,8)], SO[2(2)-1(1)], and CH3CH2CN[10(1,10)-9(1,9)], all near 3 mm wavelengh. These maps will be discussed. The HCO+distribution corresponds to the larger scale structures observed in the continuum maps. In contrast the SO and SiO sources are quite compact. Using the detailed molecular line results obtained in the ORION/KL region as a guide, we are able to identify these latter sources as regions in which the star formation is at an earlier stage, regions where there are outflows.

scholarly journals The Radio Spectrum of SGR A∗

1996 ◽  
Vol 171 ◽  
pp. 342-342 ◽  
Author(s):  
T. Beckert ◽  
W.J. Duschl ◽  
P.G. Mezger ◽  
R. Zylka
Keyword(s):  
Radio Source ◽  
Flux Density ◽  
Radio Spectrum ◽  
Frequency Range ◽  
Upper Limits ◽  
The Galaxy ◽  
Sgr A

Sgr A∗, the enigmatic radio source located at the dynamical center of the Galaxy, is firmly detected in the frequency range of ∼ 1 – few 102 GHz. For ∼ 0.5 – 1 GHz and in the MIR range only significant upper limits of the flux density are known. Between ∼ 1.5 and 600 GHz the time averaged flux density Sv is proportional to v1/3 (v: frequency). For frequencies higher than ∼ 600 GHz as well as for those lower than ∼ 1.5 GHz, Sv drops sharply.

11205 Vibration Energy Control in mid frequency range based on principal component analysis

2013 ◽  
Vol 2013.19 (0) ◽  
pp. 151-152
Author(s):  
Yuta II ◽  
Kohei FURUYA ◽  
Nobuyuki OKUBO ◽  
Takeshi TOI ◽  
Atsushi SETO ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Principal Component ◽  
Component Analysis ◽  
Vibration Energy ◽  
Frequency Range ◽  
Energy Control

Sagittarius A

1967 ◽  
Vol 31 ◽  
pp. 393-404 ◽  
Author(s):  
J. Lequeux
Keyword(s):  
Short Wave ◽  
Galactic Centre ◽  
High Angular Resolution ◽  
Thermal Source ◽  
Thermal Index ◽  
Sagittarius A ◽  
The Galaxy ◽  
External Galaxies ◽  
Sgr A ◽  
Thermal Sources

The available high-resolution observations of the complex of radio sources in the region of the galactic centre are reviewed and analysed. As noted by Downes and Maxwell, the spectrum of the strong central source, Sagittarius A, is markedly non-thermal (index 0·7) at high frequencies; below 3000 MHz the spectrum may be flat, but flux values obtained at high angular resolution are badly needed.Various arguments indicate that the whole source complex is located near the nucleus of the Galaxy. From the short-wave observations collected by Downes and Maxwell dimensions, densities and masses are estimated for the thermal sources. The total mass of ionized hydrogen in these sources is about 106M⊙; the mechanism of ionization is uncertain.The non-thermal source Sgr A may be similar to the optical nuclei of external galaxies. Its synchrotron emission, as well as the outward motions and tilted features observed in the 21-cm line and continuum, are signs of activity in the galactic nucleus; but the time-scales of the various phenomena appear to disagree.

scholarly journals Resolved optical-infrared SEDs of galaxies: universal relations and their break-down on local scales

2011 ◽  
Vol 7 (S284) ◽  
pp. 117-121
Author(s):  
Stefano Zibetti ◽  
Brent Groves
Keyword(s):  
Rest Frame ◽  
Large Body ◽  
Principal Component ◽  
Strong Correlations ◽  
Physical Conditions ◽  
The Galaxy ◽  
Multi Wavelength ◽  
Nearby Galaxies ◽  
Star Formation Histories ◽  
Stellar Dust

AbstractA large body of evidence has demonstrated that the global rest-frame optical and IR colours of galaxies correlate well with each other, which can be readily interpreted as a sign of typically smooth star formation histories. However the processes that lead to the observed correlations are contrary: the stellar light that contributes to the optical is readily absorbed by dust which emits in the IR. Thus on small scales we expect these correlations to break down. In this contribution we present our recent results (Zibetti & Groves 2011) from a pixel-by-pixel multi-wavelength (u-band to 8μm) analysis of seven nearby galaxies ranging from early- to late-types. We show that such a break-down occurs already on scales on few 100 pc, as a result of the different physical conditions in spatially distinct regions inside the galaxy, as we demonstrate by means of a Principal Component Analysis. Despite the lack of internal correlation between optical and IR within individual galaxies, when the pixels of all galaxies are compared the well known optical-IR colour correlations return, demonstrating that the variance observed within galaxies is limited around a mean which follows the well-known trends. We also examine the extremely strong correlations between the mid IR (Spitzer-IRAC)-NIR colours which extend continuously across all galaxies. These correlations arise from the differing contribution of stellar light and dust to the IRAC bands, enabling us to determine pure stellar colours for these bands, but still demonstrating the need for dust (or stellar) corrections in these bands when being used as stellar (dust) tracers.

Ammonia Mapping of the Southern Molecular Cloud NGC 6334

1987 ◽  
Vol 7 (2) ◽  
pp. 189-193 ◽  
Author(s):  
J. R. Forster ◽  
J. B. Whiteoak ◽  
F. F. Gardner ◽  
W. L. Peters ◽  
T. B. H. Kuiper
Keyword(s):  
Molecular Cloud ◽  
Line Emission ◽  
Ammonia Emission ◽  
Molecular Line ◽  
Ir Sources ◽  
Linear Resolution ◽  
The Galaxy ◽  
Velocity Anomalies ◽  
Ngc 6334 ◽  
Cloud Complex

AbstractThe Parkes 64-m antenna has been used to map ammonia emission in the (J,K = 1,1) and (J,K = 2,2) transitions toward molecular cloud complex NGC 6334. This complex contains a number of OH and H2O masers, HII regions and IR sources, and is a rich source of molecular line emission.Distributions of observed and derived quantities are presented with a linear resolution of ∼ 1 pc. Velocity anomalies are present near the two OH masers NGC 6334A and B, and the source of ammonia emission located near the northernmost H2O maser is one of the most intense sources of NH3 emission in the Galaxy.

The Velocities of 6cm Recombination Line Emission originating near the Galactic Nucleus

1977 ◽  
Vol 3 (2) ◽  
pp. 150-152 ◽  
Author(s):  
F. F. Gardner ◽  
J. B. Whiteoak
Keyword(s):  
Radio Source ◽  
Strong Evidence ◽  
Line Emission ◽  
Hii Regions ◽  
Galactic Centre ◽  
Recombination Line ◽  
The Galaxy ◽  
Centre Region ◽  
Sgr A

Although it is well known that HII regions are present in the innermost regions of the Galaxy their kinematics are still not fully understood. In one study Pauls et al. (1976) surveyed with a beamwidth of 3′ arc the 10 GHz recombination line emission in directions within 15′ arc of the nuclear radio source Sgr A. They found that the emission velocities varied from position to position within the range -50 to + 50 km s-1but appeared to lack any overall pattern. In contrast, we have recently observed the recombination line emission from the galactic centre region with a beamwidth of 4′.5 arc, and find strong evidence of ordered motions near the galactic nucleus.

The Population I Core of the Galaxy

1994 ◽  
Vol 11 (2) ◽  
pp. 191-193 ◽  
Author(s):  
David Allen ◽  
Michael Burton
Keyword(s):  
Mass Loss ◽  
Radio Source ◽  
Galactic Centre ◽  
Overtone Band ◽  
Nonthermal Radio ◽  
The Galaxy ◽  
Sgr A

Abstract We demonstrate the presence of a cluster of hot, population I stars at the very centre of the Galaxy, using the depth of the first overtone band of CO and the presence of emission in He I 2 ·058 μm and [Fell] 1·644μm to identify stars. The cluster is very compact and comprises at least several hundred stars. They lie close to the nonthermal radio source Sgr A* and dominate the luminosity and mass loss of the Galactic core. Their presence suggests that a starburst occurred at the Galactic centre.

scholarly journals Molecular Gas Excitation and Chemistry in VV 114 and NGC 1614 with ALMA

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
Toshiki Saito ◽  
Daisuke Iono ◽  
Junko Ueda ◽  
Min S. Yun ◽  
Kouichiro Nakanishi ◽  
...  
Keyword(s):  
Band 3 ◽  
Molecular Gas ◽  
Infrared Galaxies ◽  
Molecular Line ◽  
Luminous Infrared Galaxies ◽  
Physical Conditions ◽  
Spatial Properties ◽  
Processing Line ◽  
Molecular Lines ◽  
Line Imaging

AbstractWe present high resolution molecular line observations of dusty AGN and starburst in nearby luminous infrared galaxies (LIRGs), VV 114 (band 3/4/7) and NGC 1614 (band 3/6/7/9), with ALMA. Multi-frequency imaging from 4.8 GHz to 691 GHz of NGC 1614 allows us to study spatial properties of the radio-to-FIR continuum and multiple CO transitions, and we find the CO excitation up to Jupp = 6 can be explained by a single ISM model powered by nuclear starbursts. Our processing line imaging survey for VV 114 detected at least 30 molecular lines which show different chemical composition from region to region. Multi-molecule imaging helps us to diagnose the chemical differences of dusty ISM, while multi-transition imaging allows us to investigate gas physical conditions affected by nuclear activities directly.

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