A Southern Hemisphere Survey of the Galactic Plane at 5 GHz

Haynes, R. F.; Caswell, J. L.; Simons, Lwj

doi:10.1071/ph780351

Cited by 47 publications

(63 citation statements)

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“…There are also apparent enhancements in the counts for l p 26Њ-28Њ, 31Њ .5-34Њ, and 3) sources; note the anticorrelation with the total counts. These directions are labeled with the corresponding star-forming regions or "R" for strong radio continuum (Altenhoff et al 1970;Haynes et al 1978). The dark stripe at l p 301Њ-306Њ is a region of missing data.…”

Section: Glimpse Counts As a Function Of Longitude And Latitudementioning

confidence: 99%

First GLIMPSE Results on the Stellar Structure of the Galaxy

Benjamin

Churchwell

Babler

et al. 2005

ApJ

390

409

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The GLIMPSE (Galactic Legacy Mid-Plane Survey Extraordinaire) Point Source Catalog of ∼30 million midinfrared sources toward the inner Galaxy, 10Њ ≤ FlF ≤ 65Њ and FbF ≤ 1Њ, was used to determine the distribution of stars in Galactic longitude, l, latitude, b, and apparent magnitude, m. The counts versus longitude can be approximated by the modified Bessel function N p N 0 (l/l 0 )K 1 (l/l 0 ), where l 0 is insensitive to limiting magnitude, band choice, and side of Galactic center: l 0 p 17Њ-30Њ with a best-fit value in the 4.5 mm band of l 0 p 24Њ ‫ע‬ 4Њ. Modeling the source distribution as an exponential disk yields a radial scale length of H * p 3.9 ‫ע‬ 0.6 kpc. There is a pronounced north-south asymmetry in source counts for FlF Շ 30Њ, with ∼25% more stars in the north. For l p 10Њ-30Њ, there is a strong enhancement of stars of m p 11.5-13.5 mag. A linear bar passing through the Galactic center with half-length R bar p 4.4 ‫ע‬ 0.5 kpc, tilted by f p 44Њ ‫01ע‬Њ to the Sun-Galactic center line, provides the simplest interpretation of these data. We examine the possibility that enhanced source counts at l p 26Њ-28Њ, 31Њ .5-34Њ, and 306Њ-309Њ are related to Galactic spiral structure. Total source counts are depressed in regions where the counts of red objects (m K Ϫm [8.0] 1 3) peak. In these areas, the counts are reduced by extinction due to molecular gas, high diffuse backgrounds associated with star formation, or both.

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Section: Glimpse Counts As a Function Of Longitude And Latitudementioning

confidence: 99%

First GLIMPSE Results on the Stellar Structure of the Galaxy

Benjamin

Churchwell

Babler

et al. 2005

ApJ

390

409

View full text Add to dashboard Cite

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“…Hinshaw et al (2007) used the maximum entropy method for the component separation of the WMAP data, where the extinction-corrected Hα template (Finkbeiner 2003;Bennett et al 2003) was used to derive thermal free-free emission. Using the Effelsberg λ21 cm (Reich et al 1990b), λ11 cm survey data (Reich et al 1990a), together with the Parkes λ6 cm data (Haynes et al 1978), Paladini et al (2005, hereafter P05) did the component separation for a thin layer of the inner Galactic plane (20…”

Section: Introductionmentioning

confidence: 99%

Thermal and non-thermal emission in the Cygnus X region

Gao

Han

et al. 2013

A&A

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Context. Radio continuum observations detect non-thermal synchrotron and thermal bremsstrahlung radiation. Separation of the two different emission components is crucial for studying the properties of the Galactic interstellar medium. The Cygnus X region is one of the most complex areas in the radio sky, which contains a number of massive stars and H ii regions on the diffuse thermal and non-thermal background. More supernova remnants (SNRs) are expected to be discovered. Aims. We aim to develop a method that can properly separate the non-thermal and thermal radio continuum emission and apply it to the Cygnus X region. The result can be used to study the properties of different emission components and search for new SNRs in the complex. Methods. Multi-frequency radio continuum data from large-scale surveys were used to develop a new component-separation method. Spectral analysis was done pixel-by-pixel for the non-thermal synchrotron emission with a realistic spectral index distribution and a fixed spectral index of β = −2.1 for the thermal bremsstrahlung emission. Results. With the new method, we separate the non-thermal and thermal components of the Cygnus X region at an angular resolution of 9. 5. The thermal emission component is found to comprise 75% of the total continuum radiation at λ6 cm. Thermal diffuse emission, rather than the discrete H ii regions, is found to be the major contributor to the entire thermal budget. A smooth non-thermal emission background of 100 mK T b is found. We successfully make the large-extent known SNRs and the H ii regions embedded in the complex standing out, but no new large SNRs brighter than 1 GHz = 3.7 × 10 −21 W m −2 Hz −1 sr −1 are found.

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“…The few examples we find in the literature, where high-resolution surveys were undertaken in this frequency gap, default to efforts devoted to construct catalogues of radio sources against the high-intensity emission of the Galactic disk. Among them, we find arcminute-resolution surveys at 4.9 GHz (Altenhoff et al 1979), 5 GHz (Haynes et al 1978), and 10 GHz (Handa et al 1987). Without a dedicated instrument, free of time constraints in its observational schedule, diffuse Galactic emission will continue to lack the coverage it needs to map the sky away from the Galactic plane in this frequency gap.…”

Section: Cmb Contaminationmentioning

confidence: 95%

The 2.3 GHz continuum survey of the GEM project

Tello¹,

Villela²,

Torres³

et al. 2013

A&A

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Context. Determining the spectral and spatial characteristics of the radio continuum of our Galaxy is an experimentally challenging endeavour for improving our understanding of the astrophysics of the interstellar medium. This knowledge has also become of paramount significance for cosmology, since Galactic emission is the main source of astrophysical contamination in measurements of the cosmic microwave background (CMB) radiation on large angular scales. Aims. We present a partial-sky survey of the radio continuum at 2.3 GHz within the scope of the Galactic Emission Mapping (GEM) project, an observational program conceived and developed to reveal the large-scale properties of Galactic synchrotron radiation through a set of self-consistent surveys of the radio continuum between 408 MHz and 10 GHz. Methods. The GEM experiment uses a portable and double-shielded 5.5-m radiotelescope in altazimuthal configuration to map 60-degree-wide declination bands from different observational sites by circularly scanning the sky at zenithal angles of 30 • from a constantly rotating platform. The observations were accomplished with a total power receiver, whose front-end high electron mobility transistor (HEMT) amplifier was matched directly to a cylindrical horn at the prime focus of the parabolic reflector. The Moon was used to calibrate the antenna temperature scale and the preparation of the map required direct subtraction and destriping algorithms to remove ground contamination as the most significant source of systematic error. Results. We used 484 h of total intensity observations from two locations in Colombia and Brazil to yield 66% sky coverage from δ = −51.• 73 to δ = +34.• 78. The observations in Colombia were obtained with a horizontal HPBW of 2.• 30 ± 0.• 13 and a vertical HPBW of 1.• 92 ± 0.• 18. The pointing accuracy was 6. 84 and the RMS sensitivity was 11.42 mK. The observations in Brazil were obtained with a horizontal HPBW of 2.• 31 ± 0.• 03 and a vertical HPBW of 1.• 82 ± 0.• 12. The pointing accuracy was 5. 26 and the RMS sensitivity was 8.24 mK. The zero-level uncertainty of the combined survey is 103 mK with a temperature scale error of 5% after direct correlation with the Rhodes/HartRAO survey at 2326 MHz on a T -T plot. Conclusions. The sky brightness distribution into regions of low and high emission in the GEM survey is consistent with the appearance of a transition region as seen in the Haslam 408 MHz and WMAP K-band surveys. Preliminary results also show that the temperature spectral index between 408 MHz and the 2.3 GHz band of the GEM survey has a weak spatial correlation with these regions; but it steepens significantly from high to low emission regions with respect to the WMAP K-band survey.

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A Southern Hemisphere Survey of the Galactic Plane at 5 GHz

Cited by 47 publications

References 0 publications

First GLIMPSE Results on the Stellar Structure of the Galaxy

First GLIMPSE Results on the Stellar Structure of the Galaxy

Thermal and non-thermal emission in the Cygnus X region

The 2.3 GHz continuum survey of the GEM project

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