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

Bonnassieux, E.H.J.; Sweijen, F.; Brienza, M.; Rajpurohit, K.; Riseley, C.J.; Bonafede, A.; Jackson, N.; Morabito, L.K.; Brunetti, G.; Harwood, J.; Kappes, A.; Rottgering, H.J.; Tasse, C.; van Weeren, R.

doi:10.1051/0004-6361/202141731

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

Bonnassieux, E.H.J.; Sweijen, F.; Brienza, M.; Rajpurohit, K.; Riseley, C.J.; Bonafede, A.; Jackson, N.; Morabito, L.K.; Brunetti, G.; Harwood, J.; Kappes, A.; Rottgering, H.J.; Tasse, C.; van Weeren, R.

Authors

E.H.J. Bonnassieux

F. Sweijen

M. Brienza

K. Rajpurohit

C.J. Riseley

A. Bonafede

N. Jackson

Dr Leah Morabito leah.k.morabito@durham.ac.uk
Associate Professor

G. Brunetti

J. Harwood

A. Kappes

H.J. Rottgering

C. Tasse

R. van Weeren

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 GHz, 4.8 GHz, 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.

Citation

Bonnassieux, E., Sweijen, F., Brienza, M., Rajpurohit, K., Riseley, C., Bonafede, A., …van Weeren, R. (2022). Spectral analysis of spatially resolved 3C295 (sub-arcsecond resolution) with the International LOFAR Telescope. Astronomy & Astrophysics, 658, Article A10. https://doi.org/10.1051/0004-6361/202141731

Journal Article Type	Article
Acceptance Date	Sep 4, 2021
Online Publication Date	Sep 24, 2021
Publication Date	2022-02
Deposit Date	Oct 5, 2021
Publicly Available Date	Oct 22, 2021
Journal	Astronomy and astrophysics.
Print ISSN	0004-6361
Electronic ISSN	1432-0746
Publisher	EDP Sciences
Peer Reviewed	Peer Reviewed
Volume	658
Article Number	A10
DOI	https://doi.org/10.1051/0004-6361/202141731

Files

Accepted Journal Article (2.3 Mb)
PDF

Copyright Statement
Bonnassieux, E. H. J., Sweijen, F., Brienza, M., Rajpurohit, K., Riseley, C. J., Bonafede, A., Jackson, N., Morabito, L. K., Brunetti, G., Harwood, J., Kappes, A., Rottgering, H. J., Tasse, C. & van Weeren, R. (2021). Spectral analysis of spatially resolved 3C295 (sub-arcsecond resolution) with the International LOFAR Telescope. Astronomy & Astrophysics 658: A10. Reproduced with permission, © ESO.