LOFAR VLBI studies at 55 MHz of 4C 43.15, a z = 2.4 radio galaxy

Leah K. Morabito; Adam T. Deller; Huub Röttgering; George Miley; Eskil Varenius; Timothy W. Shimwell; Javier Moldón; Neal Jackson; Raffaella Morganti; Reinout J. van Weeren; J. B R Oonk

doi:10.1093/mnras/stw1501

LOFAR VLBI studies at 55 MHz of 4C 43.15, a z = 2.4 radio galaxy

Leah K. Morabito, Adam T. Deller, Huub Röttgering, George Miley, Eskil Varenius, Timothy W. Shimwell, Javier Moldón, Neal Jackson, Raffaella Morganti, Reinout J. van Weeren, J. B R Oonk

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Abstract

The correlation between radio spectral index and redshift has been exploited to discover highredshift radio galaxies, but its underlying cause is unclear. It is crucial to characterize the particle acceleration and loss mechanisms in high-redshift radio galaxies to understand why their radio spectral indices are steeper than their local counterparts. Low-frequency information on scales of ∼1 arcsec are necessary to determine the internal spectral index variation. In this paper we present the first spatially resolved studies at frequencies below 100MHz of the z = 2.4 radio galaxy 4C 43.15 which was selected based on its ultrasteep spectral index (α <-1; S_ν ∼ ν^α) between 365MHz and 1.4 GHz. Using the International Low Frequency Array Low Band Antenna we achieve subarcsecond imaging resolution at 55MHz with very long baseline interferometry techniques. Our study reveals low-frequency radio emission extended along the jet axis, which connects the two lobes. The integrated spectral index for frequencies

Original language	English
Article number	stw1501
Journal	Monthly Notices of the Royal Astronomical Society
Volume	461
Issue number	3
Early online date	29 Jun 2016
DOIs	https://doi.org/10.1093/mnras/stw1501
Publication status	Published - 21 Sep 2016

Keywords

galaxies: active
Galaxies: individual: 4C 43.15
Galaxies: jets
Radio continuum: galaxies

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1606 06741Accepted author manuscript, 1.2 MB

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title = "LOFAR VLBI studies at 55 MHz of 4C 43.15, a z = 2.4 radio galaxy",

abstract = "The correlation between radio spectral index and redshift has been exploited to discover highredshift radio galaxies, but its underlying cause is unclear. It is crucial to characterize the particle acceleration and loss mechanisms in high-redshift radio galaxies to understand why their radio spectral indices are steeper than their local counterparts. Low-frequency information on scales of ∼1 arcsec are necessary to determine the internal spectral index variation. In this paper we present the first spatially resolved studies at frequencies below 100MHz of the z = 2.4 radio galaxy 4C 43.15 which was selected based on its ultrasteep spectral index (α <-1; Sν ∼ να) between 365MHz and 1.4 GHz. Using the International Low Frequency Array Low Band Antenna we achieve subarcsecond imaging resolution at 55MHz with very long baseline interferometry techniques. Our study reveals low-frequency radio emission extended along the jet axis, which connects the two lobes. The integrated spectral index for frequencies ",

keywords = "galaxies: active, Galaxies: individual: 4C 43.15, Galaxies: jets, Radio continuum: galaxies",

author = "Morabito, {Leah K.} and Deller, {Adam T.} and Huub R{\"o}ttgering and George Miley and Eskil Varenius and Shimwell, {Timothy W.} and Javier Mold{\'o}n and Neal Jackson and Raffaella Morganti and {van Weeren}, {Reinout J.} and Oonk, {J. B R}",

year = "2016",

month = sep,

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doi = "10.1093/mnras/stw1501",

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AU - Morabito, Leah K.

AU - Deller, Adam T.

AU - Röttgering, Huub

AU - Miley, George

AU - Varenius, Eskil

AU - Shimwell, Timothy W.

AU - Moldón, Javier

AU - Jackson, Neal

AU - Morganti, Raffaella

AU - van Weeren, Reinout J.

AU - Oonk, J. B R

PY - 2016/9/21

Y1 - 2016/9/21

N2 - The correlation between radio spectral index and redshift has been exploited to discover highredshift radio galaxies, but its underlying cause is unclear. It is crucial to characterize the particle acceleration and loss mechanisms in high-redshift radio galaxies to understand why their radio spectral indices are steeper than their local counterparts. Low-frequency information on scales of ∼1 arcsec are necessary to determine the internal spectral index variation. In this paper we present the first spatially resolved studies at frequencies below 100MHz of the z = 2.4 radio galaxy 4C 43.15 which was selected based on its ultrasteep spectral index (α <-1; Sν ∼ να) between 365MHz and 1.4 GHz. Using the International Low Frequency Array Low Band Antenna we achieve subarcsecond imaging resolution at 55MHz with very long baseline interferometry techniques. Our study reveals low-frequency radio emission extended along the jet axis, which connects the two lobes. The integrated spectral index for frequencies

AB - The correlation between radio spectral index and redshift has been exploited to discover highredshift radio galaxies, but its underlying cause is unclear. It is crucial to characterize the particle acceleration and loss mechanisms in high-redshift radio galaxies to understand why their radio spectral indices are steeper than their local counterparts. Low-frequency information on scales of ∼1 arcsec are necessary to determine the internal spectral index variation. In this paper we present the first spatially resolved studies at frequencies below 100MHz of the z = 2.4 radio galaxy 4C 43.15 which was selected based on its ultrasteep spectral index (α <-1; Sν ∼ να) between 365MHz and 1.4 GHz. Using the International Low Frequency Array Low Band Antenna we achieve subarcsecond imaging resolution at 55MHz with very long baseline interferometry techniques. Our study reveals low-frequency radio emission extended along the jet axis, which connects the two lobes. The integrated spectral index for frequencies

KW - galaxies: active

KW - Galaxies: individual: 4C 43.15

KW - Galaxies: jets

KW - Radio continuum: galaxies

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JO - Royal Astronomical Society. Monthly Notices

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LOFAR VLBI studies at 55 MHz of 4C 43.15, a z = 2.4 radio galaxy

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