A High Resolution Survey of the Galactic Plane at 408 MHz

Tung, A. K.; Kothes, R.; Landecker, T. L.; Geisbüsch, Jörn; Rizzo, D. Del; Brunt, Christopher M.; Gray, A. D.; Dougherty, S. M.

doi:10.3847/1538-3881/aa866d

“…G107.0+9.0 is barely visible in the 51 -resolution 408-MHz allsky survey maps (Haslam et al 1982). It is much better traced by the CGPS high-latitude extension at 408 MHz (Tung et al 2017), which combines single-dish, large-scale emission from the 408-MHz all-sky survey (Haslam et al 1982) and interferometric data. The CGPS 408-MHz survey has an angular resolution of 2.…”

Section: -Mhz Datamentioning

confidence: 99%

“…This indicates that radio emission should be visible in low-frequency surveys as well, and we checked the 22-MHz survey (Roger et al 1999) and the 408-MHz survey (Haslam et al 1982). The area of G107.0+9.0 is also covered by the high-latitude extension of the Canadian Galactic plane survey (CGPS in the following) at 408 MHz (Tung et al 2017) and 1420 MHz (Landecker et al 2010). These maps have arc-minute angular resolution and are corrected for missing large-scale emission by single-dish data.…”

Section: Introductionmentioning

confidence: 99%

Radio properties of the optically identified supernova remnant G107.0+9.0

Reich

¹

,

Gao

²

,

Reich

³

2021

A&A

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Context. The vast majority of Galactic supernova remnants (SNRs) were detected by their synchrotron radio emission. Recently, the evolved SNR G107.0+9.0 with a diameter of about 3 • or 75 pc up to 100 pc in size was optically detected with an indication of faint associated radio emission. This SNR requires a detailed radio study. Aims. We aim to search for radio emission from SNR G107.0+9.0 by analysing new data from the Effelsberg 100-m and the Urumqi 25-m radio telescopes in addition to available radio surveys. Methods. Radio SNRs outside of the Galactic plane, where confusion is rare, must be very faint if they have not been identified so far. Guided by the Hα emission of G107.0+9.0, we separated its radio emission from the Galactic large-scale emission. Results. Radio emission from SNR G107.0+9.0 is detected between 22 MHz and 4.8 GHz with a steep non-thermal spectrum, which confirms G107.0+9.0 as an SNR. Its surface brightness is among the lowest known for Galactic SNRs. Polarised emission is clearly detected at 1.4 GHz but is fainter at 4.8 GHz. We interpret the polarised emission as being caused by a Faraday screen associated with G107.0+9.0 and its surroundings. Its ordered magnetic field along the line of sight is below 1 µG. At 4.8 GHz, we identified a depolarised filament along the western periphery of G107.0+9.0 with a magnetic field strength along the line of sight B || ∼ 15 µG, which requires magnetic field compression. Conclusions. G107.0+9.0 adds to the currently small number of known, evolved, large-diameter, low-surface-brightness Galactic SNRs. We have shown that such objects can be successfully extracted from radio-continuum surveys despite the dominating large-scale diffuse Galactic emission.

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“…G107.0+9.0 is barely visible in the 51 ′ -resolution 408-MHz allsky survey maps (Haslam et al 1982). It is much better traced by the CGPS high-latitude extension at 408 MHz (Tung et al 2017), which combines single-dish, large-scale emission from the 408-MHz all-sky survey (Haslam et al 1982) and interferometric data. The CGPS 408-MHz survey has an angular resolution of 2 ′ .8 × 2 ′ .8 × cosec(dec).…”

Section: -Mhz Datamentioning

confidence: 99%

Radio properties of the optically identified supernova remnant G107.0+9.0

Reich,

Gao,

Reich

2021

Preprint

0

View full text Add to dashboard Cite

Context. The vast majority of Galactic supernova remnants (SNRs) were detected by their synchrotron radio emission. Recently, the evolved SNR G107.0+9.0 with a diameter of about 3 • or 75 pc up to 100 pc in size was optically detected with an indication of faint associated radio emission. This SNR requires a detailed radio study. Aims. We aim to search for radio emission from SNR G107.0+9.0 by analysing new data from the Effelsberg 100-m and the Urumqi 25-m radio telescopes in addition to available radio surveys. Methods. Radio SNRs outside of the Galactic plane, where confusion is rare, must be very faint if they have not been identified so far. Guided by the Hα emission of G107.0+9.0, we separated its radio emission from the Galactic large-scale emission. Results. Radio emission from SNR G107.0+9.0 is detected between 22 MHz and 4.8 GHz with a steep non-thermal spectrum, which confirms G107.0+9.0 as an SNR. Its surface brightness is among the lowest known for Galactic SNRs. Polarised emission is clearly detected at 1.4 GHz but is fainter at 4.8 GHz. We interpret the polarised emission as being caused by a Faraday screen associated with G107.0+9.0 and its surroundings. Its ordered magnetic field along the line of sight is below 1 µG. At 4.8 GHz, we identified a depolarised filament along the western periphery of G107.0+9.0 with a magnetic field strength along the line of sight B || ∼ 15 µG, which requires magnetic field compression. Conclusions. G107.0+9.0 adds to the currently small number of known, evolved, large-diameter, low-surface-brightness Galactic SNRs. We have shown that such objects can be successfully extracted from radio-continuum surveys despite the dominating largescale diffuse Galactic emission.

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“…Other departures from the overall trend can be seen in Figures 2 and 6, but are less obvious in Figure 4. We can identify these features with H II regions or supernova remnants through comparison with CGPS images of the total-intensity along the Galactic plane; we use the 408-MHz maps of Tung et al (2017), especially their Figures 6 to 12:…”

Section: Localized Anomaliesmentioning

confidence: 99%

Revisiting Rotation Measures from the Canadian Galactic Plane Survey: the Magnetic Field in the Disk of the Outer Galaxy

Van Eck,

Brown,

Ordog

et al. 2021

Preprint

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0

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Faraday rotation provides a valuable tracer of magnetic fields in the interstellar medium; catalogs of Faraday rotation measures provide key observations for studies of the Galactic magnetic field. We present a new catalog of rotation measures derived from the Canadian Galactic Plane Survey, covering a large region of the Galactic plane spanning 52along with northern and southern latitude extensions around l ≈ 105 • . We have derived rotation measures for 2234 sources (4 of which are known pulsars), 75% of which have no previous measurements, over an area of approximately 1300 square degrees. These new rotation measures increase the measurement density for this region of the Galactic plane by a factor of two.1 Faraday-simple refers to a line of sight with a single dominant source of polarized emission, with all of that emission undergoing the same amount of Faraday rotation. Lines of sight with multiple polarized components with different Faraday rotation are called Faraday-complex.

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A High Resolution Survey of the Galactic Plane at 408 MHz

Cited by 14 publications

References 50 publications

Radio properties of the optically identified supernova remnant G107.0+9.0

Radio properties of the optically identified supernova remnant G107.0+9.0

Radio properties of the optically identified supernova remnant G107.0+9.0

Revisiting Rotation Measures from the Canadian Galactic Plane Survey: the Magnetic Field in the Disk of the Outer Galaxy

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