Radio Counterparts of Gamma-Ray Sources in the Cygnus Region

Benaglia, P.; Ishwara‐Chandra, C. H.; Paredes, J. M.; Intema, H. T.; Colazo, Marcelo; Isequilla, N. L.

doi:10.3847/1538-4365/abc891

Cited by 5 publications

(7 citation statements)

References 44 publications

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“…The understanding of the γ Cygni SNR could profit from future observation particularly of radio emission and the molecular material, the uncovered hard X-ray to sub-GeV energy range, and very high-energy γ rays. Deep radio observations like the one performed by Benaglia et al (2021) could help to better understand the connection between the radio and the very highenergy emission from the region, and thus provide further information on the nature of the γ-ray emitter. Improved knowledge of the target material can reduce the uncertainty of our proposed model and determine the contribution from hadrons.…”

Section: Summary and Future Prospectsmentioning

confidence: 99%

Study of the GeV to TeV morphology of the γ Cygni SNR (G 78.2+2.1) with MAGIC and Fermi-LAT

Acciari

Ansoldi

Antonelli

et al. 2023

A&A

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Context. Diffusive shock acceleration (DSA) is the most promising mechanism that accelerates Galactic cosmic rays (CRs) in the shocks of supernova remnants (SNRs). It is based on particles scattering caused by turbulence ahead and behind the shock. The turbulence upstream is supposedly generated by the CRs, but this process is not well understood. The dominant mechanism may depend on the evolutionary state of the shock and can be studied via the CRs escaping upstream into the interstellar medium (ISM). Aims. Previous observations of the γ Cygni SNR showed a difference in morphology between GeV and TeV energies. Since this SNR has the right age and is at the evolutionary stage for a significant fraction of CRs to escape, our aim is to understand γ-ray emission in the vicinity of the γ Cygni SNR. Methods. We observed the region of the γ Cygni SNR with the MAGIC Imaging Atmospheric Cherenkov telescopes between 2015 May and 2017 September recording 87 h of good-quality data. Additionally, we analysed Fermi-LAT data to study the energy dependence of the morphology as well as the energy spectrum in the GeV to TeV range. The energy spectra and morphology were compared against theoretical predictions, which include a detailed derivation of the CR escape process and their γ-ray generation.Results. The MAGIC and Fermi-LAT data allowed us to identify three emission regions that can be associated with the SNR and that dominate at different energies. Our hadronic emission model accounts well for the morphology and energy spectrum of all source components. It constrains the time-dependence of the maximum energy of the CRs at the shock, the time-dependence of the level of turbulence, and the diffusion coefficient immediately outside the SNR shock. While in agreement with the standard picture of DSA, the time-dependence of the maximum energy was found to be steeper than predicted, and the level of turbulence was found to change over the lifetime of the SNR.

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Section: Summary and Future Prospectsmentioning

confidence: 99%

Study of the GeV to TeV morphology of the γ Cygni SNR (G 78.2+2.1) with MAGIC and Fermi-LAT

Acciari

Ansoldi

Antonelli

et al. 2023

A&A

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“…In the case of extended sources, we derived the spectral indices using the 610 MHz image convolved to the 325 MHz synthesised beam of 10 ×10 . Other sources, mainly point-like sources, were identified and catalogued by Benaglia et al (2020Benaglia et al ( , 2021 and they are not considered here.…”

Section: The 325 and 610 Mhz Radio Datamentioning

confidence: 99%

“…While the atomic and molecular material in the region provides a sufficient density, a clear counterpart could not be identified and thus the possibility for an extended source unrelated to the SNR cannot be ruled out (MAGIC Collaboration et al 2020). Benaglia et al (2020Benaglia et al ( , 2021, using the Giant Metrewave Radio Telescope (GMRT) at 325 MHz and 610 MHz, performed a deep survey of the Cygnus region that included the γ Cygni SNR and its nearby surroundings. A detailed study of the γ Cygni SNR was beyond the scope of these publications and was planned to be carried out in a future work.…”

Section: Introductionmentioning

confidence: 99%

Exploring the region encompassing γ Cygni SNR and MAGIC J2019+408 with the GMRT at 325 and 610 MHz

Paredes

Benaglia

Ishwara‐Chandra

et al. 2022

A&A

Self Cite

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Context. γ Cygni is a young supernova remnant located in the Cygnus region. MAGIC (Major Atmospheric Gamma Imaging Cherenkov) telescopes detected TeV emission (MAGIC J2019+408) to the north-west of this remnant, ∼ 5 from its border. Aims. We want to identify the radio sources within the region encompassing γ Cygni and MAGIC J2019+408 to shed light on their nature and investigate if these radio sources could be potential contributors to gamma-ray emission. Methods. We carried out a detailed study of the data we obtained with a survey of the Cygnus region at 325 and 610 MHz with the Giant Metrewave Radio Telescope (GMRT). Results. We detected several radio sources in the region where the radio and the TeV emission overlap, as well as several areas of enhanced radio emission. In particular, two of these areas of diffuse enhanced emission may correspond to the supernova remnant interacting with a high density region, which seems to be the best candidate for the MAGIC source. Another two radio sources, which may or may not contribute to the gamma rays, are also spatially coincident with the emission peak of the MAGIC TeV source. One of them displays a rather peculiar extended morphology whose nature is completely unknown. Conclusions. We have identified the radio sources overlapping γ Cygni and MAGIC J2019+408 and have shown that their potential gamma-ray contribution is likely not dominant. In addition, some of the studied sources show peculiar physical characteristics that deserve deeper multi-wavelength observations.

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“…On the other hand, Miller-Jones et al ( 2007) detected diffuse emission in the vicinity of Cygnus X-3 at a frequency of 330 MHz (left panel of their figure 3; synthesized beam 93 × 59 arcsec 2 and PA 3. • 3); also see the 325-MHz detection in Benaglia et al (2021). We inspected the corresponding image file (J. Miller-Jones, priv.…”

Section: Data Availabilitymentioning

confidence: 99%

Strong low-frequency radio flaring from Cygnus X-3 observed with LOFAR

Broderick

Russell

Fender

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We present Low-Frequency Array (LOFAR) 143.5-MHz radio observations of flaring activity during 2019 May from the X-ray binary Cygnus X-3. Similar to radio observations of previous outbursts from Cygnus X-3, we find that this source was significantly variable at low frequencies, reaching a maximum flux density of about 5.8 Jy. We compare our LOFAR light curve with contemporaneous observations taken at 1.25 and 2.3 GHz with the RATAN-600 telescope, and at 15 GHz with the Arcminute Microkelvin Imager (AMI) Large Array. The initial 143.5-MHz flux density level, ∼2 Jy, is suggested to be the delayed and possibly blended emission from at least some of the flaring activity that had been detected at higher frequencies before our LOFAR observations had begun. There is also evidence of a delay of more than four days between a bright flare that initially peaked on May 6 at 2.3 and 15 GHz, and the corresponding peak (≳ 5.8 Jy) at 143.5 MHz. From the multi-frequency light curves, we estimate the minimum energy and magnetic field required to produce this flare to be roughly 1044 erg and 40 mG, respectively, corresponding to a minimum mean power of ∼1038 erg s−1. Additionally, we show that the broadband radio spectrum evolved over the course of our observing campaign; in particular, the two-point spectral index between 143.5 MHz and 1.25 GHz transitioned from being optically thick to optically thin as the flare simultaneously brightened at 143.5 MHz and faded at GHz frequencies.

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Radio Counterparts of Gamma-Ray Sources in the Cygnus Region

Cited by 5 publications

References 44 publications

Study of the GeV to TeV morphology of the γ Cygni SNR (G 78.2+2.1) with MAGIC and Fermi-LAT

Study of the GeV to TeV morphology of the γ Cygni SNR (G 78.2+2.1) with MAGIC and Fermi-LAT

Exploring the region encompassing γ Cygni SNR and MAGIC J2019+408 with the GMRT at 325 and 610 MHz

Strong low-frequency radio flaring from Cygnus X-3 observed with LOFAR

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