The Parkes-MIT-NRAO (PMN) surveys. 6: Source catalog for the equatorial survey (-9.5 deg less than delta less than +10.0 deg)

Griffith, Mark R.; Wright, A. E.; Burke, B. F.; Ekers, R. D.

doi:10.1086/192146

Cited by 202 publications

(161 citation statements)

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“…The total NVSS radio flux density (power) is 429 ± 14 mJy (2.18 ± 0.07 × 10 34 erg s −1 Hz −1 ); the radio flux density from the NVSS is a more reliable measure of the total radio flux, since the VLA-B configuration used for the FIRST survey could miss some of the diffuse extended emission. For this source we also found in the literature fluxes at 178 MHz ( f 178MHz = 2.6 ± 0.65 Jy; Gower et al 1967) and 4.85 GHz ( f 4.85GHz = 0.116 ± 0.012 Jy; Griffith et al 1995); assuming a power-law model the derived radio spectral index is ∼ 0.94, consistent with the typical values of lobe-dominated AGN (Kellermann & Owen 1988).…”

Section: Resultssupporting

confidence: 86%

Exploring the active galactic nuclei population with extreme X-ray-to-optical flux ratios (fx/fo > 50)

Ceca

Carrera

Caccianiga

et al. 2015

Monthly Notices of the Royal Astronomical Society

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The cosmic history of the growth of supermassive black holes in galactic centers parallels that of star-formation in the Universe. However, an important fraction of this growth occurs inconspicuously in obscured objects, where ultraviolet/optical/near-infrared emission is heavily obscured by dust. Since the X-ray flux is less attenuated, a high X-ray-to-optical flux ratio ( f x / f o ) is expected to be an efficient tool to find out these obscured accreting sources. We explore here via optical spectroscopy, X-ray spectroscopy and infrared photometry the most extreme cases of this population (those with f x / f o > 50, EXO50 sources hereafter), using a well defined sample of 7 X-ray sources extracted from the 2XMM catalogue. Five EXO50 sources (∼ 70 percent of the sample) in the bright flux regime explored by our survey ( f (2−10keV) 1.5 × 10 −13 erg cm −2 s −1 ) are associated with obscured AGN (N H > 10 22 cm −2 ), spanning a redshift range between 0.75 and 1 and characterised by 2-10 keV intrinsic luminosities in the QSO regime (e.g. well in excess to 10 44 erg s −1 ). We did not find compelling evidence of Compton Thick AGN. Overall the EXO50 Type 2 QSOs do not seem to be different from standard X-ray selected Type 2 QSOs in terms of nuclear absorption; a very high AGN/host galaxy ratio seems to play a major role in explaining their extreme properties. Interestingly 3 out of 5 EXO50 Type 2 QSO objects can be classified as Extreme Dust Obscured Galaxies (EDOGs, f 24 µm / f R 2000), suggesting that a very high AGN/host ratios (along with the large amount of dust absorption) could be the natural explanation also for a part of the EDOG population. The remaining 2 EXO50 sources are classified as BL Lac objects, having rather extreme properties, and which are good candidates for TeV emission.

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Section: Resultssupporting

confidence: 86%

Exploring the active galactic nuclei population with extreme X-ray-to-optical flux ratios (fx/fo > 50)

Ceca

Carrera

Caccianiga

et al. 2015

Monthly Notices of the Royal Astronomical Society

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“…Distribution of estimated electron temperature (T e ) of HII regions from radio recombination line and radio continuum observations in Table A. 1. here, T e is the electron temperature in K; S ν is the radio flux density in Jy, collected from literature (e.g., Downes et al 1980;Caswell & Haynes 1987;Griffith et al 1995;Kuchar & Clark 1997) if available; ν is the observed frequency in GHz; D is the distance to the tracer in kpc; and α(ν, T e ) is a parameter close to 1 (Schraml & Mezger 1969), and for simplicity, we adopt α(ν, T e ) = 1. For a HII region, if T e is given in the literature, we adopt it directly.…”

Section: Weights For Tracers Of Galactic Spiral Structurementioning

confidence: 99%

The observed spiral structure of the Milky Way

Hou

Han

2014

A&A

226

242

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Context. The spiral structure of the Milky Way is not yet well determined. The keys to understanding this structure are to increase the number of reliable spiral tracers and to determine their distances as accurately as possible. HII regions, giant molecular clouds (GMCs), and 6.7 GHz methanol masers are closely related to high mass star formation, and hence they are excellent spiral tracers. The distances for many of them have been determined in the literature with trigonometric, photometric, and/or kinematic methods. Aims. We update the catalogs of Galactic HII regions, GMCs, and 6.7 GHz methanol masers, and then outline the spiral structure of the Milky Way. Methods. We collected data for more than 2500 known HII regions, 1300 GMCs, and 900 6.7 GHz methanol masers. If the photometric or trigonometric distance was not yet available, we determined the kinematic distance using a Galaxy rotation curve with the current IAU standard, R 0 = 8.5 kpc and Θ 0 = 220 km s −1 , and the most recent updated values of R 0 = 8.3 kpc and Θ 0 = 239 km s −1 , after velocities of tracers are modified with the adopted solar motions. With the weight factors based on the excitation parameters of HII regions or the masses of GMCs, we get the distributions of these spiral tracers.Results. The distribution of tracers shows at least four segments of arms in the first Galactic quadrant, and three segments in the fourth quadrant. The Perseus Arm and the Local Arm are also delineated by many bright HII regions. The arm segments traced by massive star forming regions and GMCs are able to match the HI arms in the outer Galaxy. We found that the models of three-arm and four-arm logarithmic spirals are able to connect most spiral tracers. A model of polynomial-logarithmic spirals is also proposed, which not only delineates the tracer distribution, but also matches the observed tangential directions.

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“…We searched the literature for flux density measurements at 408 MHz for these 97 sources. If such measurements were unavailable, we used the radio spectrum or unpublished Molonglo 408 MHz Day et al 1966; (7) Shimmins et al 1966;(8) Shimmins & Day 1968;(9) Bolton et al 1979 and references therein; (10) Large et al 1981;(11) Griffith et al 1994;(12) Wright et al 1994;(13) Griffith et al 1995;(14) Wright et al 1996. data. As a result of these estimates, described in x 2.3, 20 extended sources were added to the sample, bringing the total number of sources to 228.…”

Section: Initial Selection Of the Samplementioning

confidence: 99%

The Molonglo Southern 4 Jy Sample (MS4). I. Definition

Burgess

Hunstead

2006

Astron J

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We have defined a complete sample of 228 southern radio sources at 408 MHz with integrated flux densities S 408 > 4:0 Jy, Galactic latitude jbj > 10 , and declination À85 < < À30 . The main finding survey used was the Molonglo Reference Catalogue. We describe in detail how the Molonglo Southern 4 Jy sample (MS4) was assembled and its completeness assessed. Sources in the sample were imaged at 843 MHz with the Molonglo Observatory Synthesis Telescope to obtain positions accurate to about 1 00 , as well as flux densities and angular sizes; follow-up radio and optical observations are presented in Paper II. Radio spectra for the MS4 have been compiled from the literature and used to estimate flux densities at 178 MHz. The strong-source subset of MS4, with S 178 > 10:9 Jy (SMS4), provides a southern sample closely equivalent to the well-studied northern 3CRR sample. Comparison of SMS4 with 3CRR shows a reassuring similarity in source density and median flux density between the two samples.

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The Parkes-MIT-NRAO (PMN) surveys. 6: Source catalog for the equatorial survey (-9.5 deg less than delta less than +10.0 deg)

Cited by 202 publications

References 0 publications

Exploring the active galactic nuclei population with extreme X-ray-to-optical flux ratios (fx/fo > 50)

Exploring the active galactic nuclei population with extreme X-ray-to-optical flux ratios (fx/fo > 50)

The observed spiral structure of the Milky Way

The Molonglo Southern 4 Jy Sample (MS4). I. Definition

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