Spectral analysis of spatially resolved 3C295 (sub-arcsecond resolution) with the International LOFAR Telescope - INSU - Institut national des sciences de l'Univers Access content directly
Journal Articles Astronomy and Astrophysics - A&A Year : 2022

Spectral analysis of spatially resolved 3C295 (sub-arcsecond resolution) with the International LOFAR Telescope

Etienne Bonnassieux
  • Function : Author
Frits Sweijen
  • Function : Author
Marisa Brienza
  • Function : Author
Kamlesh Rajpurohit
  • Function : Author
Christopher John Riseley
  • Function : Author
Annalisa Bonafede
  • Function : Author
Neal Jackson
  • Function : Author
Leah K. Morabito
  • Function : Author
Gianfranco Brunetti
  • Function : Author
Jeremy Harwood
  • Function : Author
Alex Kappes
  • Function : Author
Huub J. Rottgering
  • Function : Author
Reinout van Weeren
  • Function : Author

Abstract

3C295 is a bright, compact steep spectrum source with a well-studied integrated radio spectral energy distribution (SED) from 132 MHz to 15 GHz. However, spatially resolved spectral studies have been limited due to a lack of high resolution images at low radio frequencies. These frequencies are crucial for measuring absorption processes, and anchoring the overall spectral modelling of the radio SED. In this paper, we use International LOw-Frequency ARray (LOFAR) Telescope (ILT) observations of 3C295 to study its spatially resolved spectral properties with sub-arcsecond resolution at 132 MHz. Combining our new 132 MHz observation with archival data at 1.6, 4.8, and 15 GHz, we are able to carry out a resolved radio spectral analysis. The spectral properties of the hotspots provides evidence for low frequency flattening. In contrast, the spectral shape across the lobes is consistent with a Jaffe-Perola spectral ageing model. Using the integrated spectral information for each component, we then fitted low-frequency absorption models to the hotspots, finding that both free-free absorption and synchrotron self-absorption models provide a better fit to the data than a standard power law. Although we can say there is low-frequency absorption present in the hotspots of 3C295, future observations with the Low Band Antenna of the ILT at 55 MHz may allow us to distinguish the type of absorption.

The reduced images are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/658/A10

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Dates and versions

insu-03719753 , version 1 (11-07-2022)

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Etienne Bonnassieux, Frits Sweijen, Marisa Brienza, Kamlesh Rajpurohit, Christopher John Riseley, et al.. Spectral analysis of spatially resolved 3C295 (sub-arcsecond resolution) with the International LOFAR Telescope. Astronomy and Astrophysics - A&A, 2022, 658, ⟨10.1051/0004-6361/202141731⟩. ⟨insu-03719753⟩
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