Radio jets in NGC 4151: where eMERLIN meets HST

D. R. A. Williams, I.M. McHardy, R. D. Baldi, R. J. Beswick, M. K. Argo, B. T. Dullo, J. H. Knapen, E. Brinks, D. M. Fenech, C. G. Mundell, T. W. B. Muxlow, F. Panessa, H. Rampadarath, J. Westcott

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Abstract

We present high-sensitivity eMERLIN radio images of the Seyfert galaxy NGC 4151 at 1.51 GHz. We compare the new eMERLIN images to those from archival MERLIN observations in 1993 to determine the change in jet morphology in the 22 yr between observations. We report an increase by almost a factor of 2 in the peak flux density of the central core component, C4, thought to host the black hole, but a probable decrease in some other components, possibly due to adiabatic expansion. The core flux increase indicates an active galactic nucleus (AGN) that is currently active and feeding the jet. We detect no significant motion in 22 yr between C4 and the component C3, which is unresolved in the eMERLIN image. We present a spectral index image made within the 512 MHz band of the 1.51 GHz observations. The spectrum of the core, C4, is flatter than that of other components further out in the jet. We use HST emission-line images (H α, [O iii] and [O ii]) to study the connection between the jet and the emission-line region. Based on the changing emission-line ratios away from the core and comparison with the eMERLIN radio jet, we conclude that photoionization from the central AGN is responsible for the observed emission-line properties further than 4 arcsec (360 pc) from the core, C4. Within this region, a body of evidence (radio-line co-spatiality, low [O iii]/H α and estimated fast shocks) suggests additional ionization from the jet.
Original languageEnglish
Pages (from-to)3842-3853
Number of pages12
JournalMonthly Notices of the Royal Astronomical Society
Volume472
Issue number4
Early online date29 Aug 2017
DOIs
Publication statusPublished - 21 Dec 2017

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radio
active galactic nuclei
Seyfert galaxies
photoionization
flux density
shock
ionization
expansion
sensitivity

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Williams, D. R. A., McHardy, I. M., Baldi, R. D., Beswick, R. J., Argo, M. K., Dullo, B. T., ... Westcott, J. (2017). Radio jets in NGC 4151: where eMERLIN meets HST. Monthly Notices of the Royal Astronomical Society, 472(4), 3842-3853. https://doi.org/10.1093/mnras/stx2205

Radio jets in NGC 4151: where eMERLIN meets HST. / Williams, D. R. A.; McHardy, I.M.; Baldi, R. D.; Beswick, R. J.; Argo, M. K.; Dullo, B. T.; Knapen, J. H.; Brinks, E.; Fenech, D. M.; Mundell, C. G.; Muxlow, T. W. B.; Panessa, F.; Rampadarath, H.; Westcott, J.

In: Monthly Notices of the Royal Astronomical Society, Vol. 472, No. 4, 21.12.2017, p. 3842-3853.

Research output: Contribution to journalArticle

Williams, DRA, McHardy, IM, Baldi, RD, Beswick, RJ, Argo, MK, Dullo, BT, Knapen, JH, Brinks, E, Fenech, DM, Mundell, CG, Muxlow, TWB, Panessa, F, Rampadarath, H & Westcott, J 2017, 'Radio jets in NGC 4151: where eMERLIN meets HST', Monthly Notices of the Royal Astronomical Society, vol. 472, no. 4, pp. 3842-3853. https://doi.org/10.1093/mnras/stx2205
Williams DRA, McHardy IM, Baldi RD, Beswick RJ, Argo MK, Dullo BT et al. Radio jets in NGC 4151: where eMERLIN meets HST. Monthly Notices of the Royal Astronomical Society. 2017 Dec 21;472(4):3842-3853. https://doi.org/10.1093/mnras/stx2205
Williams, D. R. A. ; McHardy, I.M. ; Baldi, R. D. ; Beswick, R. J. ; Argo, M. K. ; Dullo, B. T. ; Knapen, J. H. ; Brinks, E. ; Fenech, D. M. ; Mundell, C. G. ; Muxlow, T. W. B. ; Panessa, F. ; Rampadarath, H. ; Westcott, J. / Radio jets in NGC 4151: where eMERLIN meets HST. In: Monthly Notices of the Royal Astronomical Society. 2017 ; Vol. 472, No. 4. pp. 3842-3853.
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abstract = "We present high-sensitivity eMERLIN radio images of the Seyfert galaxy NGC 4151 at 1.51 GHz. We compare the new eMERLIN images to those from archival MERLIN observations in 1993 to determine the change in jet morphology in the 22 yr between observations. We report an increase by almost a factor of 2 in the peak flux density of the central core component, C4, thought to host the black hole, but a probable decrease in some other components, possibly due to adiabatic expansion. The core flux increase indicates an active galactic nucleus (AGN) that is currently active and feeding the jet. We detect no significant motion in 22 yr between C4 and the component C3, which is unresolved in the eMERLIN image. We present a spectral index image made within the 512 MHz band of the 1.51 GHz observations. The spectrum of the core, C4, is flatter than that of other components further out in the jet. We use HST emission-line images (H α, [O iii] and [O ii]) to study the connection between the jet and the emission-line region. Based on the changing emission-line ratios away from the core and comparison with the eMERLIN radio jet, we conclude that photoionization from the central AGN is responsible for the observed emission-line properties further than 4 arcsec (360 pc) from the core, C4. Within this region, a body of evidence (radio-line co-spatiality, low [O iii]/H α and estimated fast shocks) suggests additional ionization from the jet.",
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AU - Williams, D. R. A.

AU - McHardy, I.M.

AU - Baldi, R. D.

AU - Beswick, R. J.

AU - Argo, M. K.

AU - Dullo, B. T.

AU - Knapen, J. H.

AU - Brinks, E.

AU - Fenech, D. M.

AU - Mundell, C. G.

AU - Muxlow, T. W. B.

AU - Panessa, F.

AU - Rampadarath, H.

AU - Westcott, J.

PY - 2017/12/21

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N2 - We present high-sensitivity eMERLIN radio images of the Seyfert galaxy NGC 4151 at 1.51 GHz. We compare the new eMERLIN images to those from archival MERLIN observations in 1993 to determine the change in jet morphology in the 22 yr between observations. We report an increase by almost a factor of 2 in the peak flux density of the central core component, C4, thought to host the black hole, but a probable decrease in some other components, possibly due to adiabatic expansion. The core flux increase indicates an active galactic nucleus (AGN) that is currently active and feeding the jet. We detect no significant motion in 22 yr between C4 and the component C3, which is unresolved in the eMERLIN image. We present a spectral index image made within the 512 MHz band of the 1.51 GHz observations. The spectrum of the core, C4, is flatter than that of other components further out in the jet. We use HST emission-line images (H α, [O iii] and [O ii]) to study the connection between the jet and the emission-line region. Based on the changing emission-line ratios away from the core and comparison with the eMERLIN radio jet, we conclude that photoionization from the central AGN is responsible for the observed emission-line properties further than 4 arcsec (360 pc) from the core, C4. Within this region, a body of evidence (radio-line co-spatiality, low [O iii]/H α and estimated fast shocks) suggests additional ionization from the jet.

AB - We present high-sensitivity eMERLIN radio images of the Seyfert galaxy NGC 4151 at 1.51 GHz. We compare the new eMERLIN images to those from archival MERLIN observations in 1993 to determine the change in jet morphology in the 22 yr between observations. We report an increase by almost a factor of 2 in the peak flux density of the central core component, C4, thought to host the black hole, but a probable decrease in some other components, possibly due to adiabatic expansion. The core flux increase indicates an active galactic nucleus (AGN) that is currently active and feeding the jet. We detect no significant motion in 22 yr between C4 and the component C3, which is unresolved in the eMERLIN image. We present a spectral index image made within the 512 MHz band of the 1.51 GHz observations. The spectrum of the core, C4, is flatter than that of other components further out in the jet. We use HST emission-line images (H α, [O iii] and [O ii]) to study the connection between the jet and the emission-line region. Based on the changing emission-line ratios away from the core and comparison with the eMERLIN radio jet, we conclude that photoionization from the central AGN is responsible for the observed emission-line properties further than 4 arcsec (360 pc) from the core, C4. Within this region, a body of evidence (radio-line co-spatiality, low [O iii]/H α and estimated fast shocks) suggests additional ionization from the jet.

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DO - 10.1093/mnras/stx2205

M3 - Article

VL - 472

SP - 3842

EP - 3853

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 4

ER -