Radio continuum and radio recombination line observations of Sagittarius B1 and G0.6-0.0

Mehringer, David M.; Yusef‐Zadeh, F.; Palmer, Patrick; Goss, W. M.

doi:10.1086/172050

Cited by 51 publications

(92 citation statements)

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“…The recombination line study of Mehringer et al (1992) indicates that both kinematically and morphologically G0.6−0.0 is physically related to the Sgr B1 and Sgr B2 complexes. Figure 12 shows a 1.4 GHz continuum image of the Sgr B region from this study.…”

Section: H I Absorption Toward the Sgr B Complexmentioning

confidence: 99%

“…Higher resolution radio observations of Sgr B2 North (Sgr B2 (N)) and Sgr B2 Main (Sgr B2 (M)) reveal 50 compact sources at sub-arcsecond level de Pree et al 1995de Pree et al , 1996. On the other hand, the radio emission arising from the Sgr B1 complex indicates that this region is a more highly evolved star-forming region than Sgr B2 with numerous filamentary and shell-like ionized structures (Mehringer et al 1992).…”

Section: H I Absorption Toward the Sgr B Complexmentioning

confidence: 99%

“…The ionized and molecular gas in both regions have been studied at high spatial resolutions (e.g., Mehringer et al 1992Mehringer et al , 1993Mehringer et al , 1995. The ionized gas in Sgr B2 has velocities between 50 and 70 km s −1 and the ionized gas in Sgr B1 has velocities between 30 and 50 km s −1 .…”

Section: H I Absorption Toward the Sgr B Complexmentioning

confidence: 99%

“…Figure 12 shows a 1.4 GHz continuum image of the Sgr B region from this study. Small regions for which H i absorption spectra were produced are labeled according to the nomenclature of Mehringer et al (1993) for Sgr B2 and Mehringer et al (1992) for Sgr B1 and G0.06−0.0. Table 7 lists fits to various interstellar components (H i, H ii, and H 2 CO) for each of these regions.…”

Section: H I Absorption Toward the Sgr B Complexmentioning

confidence: 99%

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A HIGH-RESOLUTION SURVEY OF H I ABSORPTION TOWARD THE CENTRAL 200 pc OF THE GALACTIC CENTER

Lang¹,

Goss²,

Cyganowski³

et al. 2010

ApJS

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We present an H i absorption survey of the central 250 pc of the Galaxy. Very Large Array observations were made at 21 cm in the DnC and CnB configurations and have a resolution of ∼15 (0.6 pc at the Galactic center (GC) distance) and a velocity resolution of ∼2.5 km s −1 . This study provides H i data with high spatial resolution, comparable with the many high-resolution observations which have been made of GC sources over the past 10 years. Here we present an overview of the H i absorption toward ∼40 well-known continuum sources and a detailed comparison of the ionized, atomic, and molecular components of the interstellar medium for the Sgr B, Radio Arc, and Sgr C regions. In these well-known regions, the atomic gas appears to be closely correlated in both velocity and distribution to the ionized and molecular gas, indicating that it resides in photodissociation regions related to the H ii regions in the GC. Toward the majority of the radio continuum sources, H i absorption by the 3 kpc arm is detected, constraining these sources to lie beyond a 5 kpc distance in the Galaxy.

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Section: H I Absorption Toward the Sgr B Complexmentioning

confidence: 99%

Section: H I Absorption Toward the Sgr B Complexmentioning

confidence: 99%

Section: H I Absorption Toward the Sgr B Complexmentioning

confidence: 99%

Section: H I Absorption Toward the Sgr B Complexmentioning

confidence: 99%

See 2 more Smart Citations

A HIGH-RESOLUTION SURVEY OF H I ABSORPTION TOWARD THE CENTRAL 200 pc OF THE GALACTIC CENTER

Lang¹,

Goss²,

Cyganowski³

et al. 2010

ApJS

Self Cite

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“…Ferrière et al 2007). For example, Mezger & Pauls (1979) used thermal radio continuum radio observations to derive a central n(e) ∼26 cm −3 while Mehringer et al (1992Mehringer et al ( , 1993 derive even higher electron densities outside compact HII regions near Sgr B1 and B2 and derive an average electron density of ∼60 and 80 cm −3 over two regions ∼700 and 170 pc 2 , respectively. The conditions encountered in the most energetic region of the CMZ is likely to prevail over a much larger volume in AGNs.…”

Section: Agn Representative Model Of [C Ii] Emissionmentioning

confidence: 99%

[C ii] emission from galactic nuclei in the presence of X-rays

Langer

Pineda

2015

A&A

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Context. The luminosity of [C ii] is used as a probe of the star formation rate in galaxies, but the correlation breaks down in some active galactic nuclei (AGNs). Models of the [C ii] emission from galactic nuclei do not include the influence of X-rays on the carbon ionization balance, which may be a factor in reducing the [C ii] luminosity.Aims. We aim to determine the properties of the ionized carbon and its distribution among highly ionized states in the interstellar gas in galactic nuclei under the influence of X-ray sources. We calculate the [C ii] luminosity in galactic nuclei under the influence of bright sources of soft X-rays. Methods. We solve the balance equation of the ionization states of carbon as a function of X-ray flux, electron, atomic hydrogen, and molecular hydrogen density. These are input to models of [C ii] emission from the interstellar medium (ISM) in galactic nuclei representing conditions in the Galactic central molecular zone and a higher density AGN model. The behavior of the [C ii] luminosity is calculated as a function of the X-ray luminosity. We also solve the distribution of the ionization states of oxygen and nitrogen in highly ionized regions. Results. We find that the dense warm ionized medium (WIM) and dense photon dominated regions (PDRs) dominate the [C ii]emission when no X-rays are present. The X-rays in galactic nuclei can affect strongly the C + abundance in the WIM, converting some fraction to C 2+ and higher ionization states and thus reducing its [C ii] luminosity. For an X-ray luminosity L(X-ray) 10 43 erg s −1 the [C ii] luminosity can be suppressed by a factor of a few, and for very strong sources, L(X-ray) >10 44 erg s −1 such as found for many AGNs, the [C ii] luminosity is significantly depressed. Comparison of the model with several extragalactic sources shows that the [C ii] to far-infrared ratio declines for L(X-ray) 10 43 erg s −1 , in reasonable agreement with our model. Conclusions. We conclude that X-rays can suppress the C + abundance and, therefore, the [C ii] luminosity of the ISM in active galactic nuclei with a large X-ray flux. The X-ray flux can arise from a central massive accreting black hole and/or from many smaller discrete sources distributed throughout the nuclei. We also find that the lower ionization states of nitrogen and oxygen are also suppressed at high X-ray fluxes in warm ionized gas.

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