Dissecting galaxies: Separating star formation, shock excitation and AGN activity in the central region of NGC 613

Rebecca L. Davies; Brent Groves; Lisa J. Kewley; Anne M. Medling; Prajval Shastri; Jaya Maithil; Preeti Kharb; Julie Banfield; Fergus Longbottom; Michael A. Dopita; Elise J. Hampton; Julia Scharwächter; Ralph Sutherland; Chichuan Jin; Ingyin Zaw; Bethan James; Stéphanie Juneau

doi:10.1093/mnras/stx1559

Dissecting galaxies: Separating star formation, shock excitation and AGN activity in the central region of NGC 613

Rebecca L. Davies^*, Brent Groves, Lisa J. Kewley, Anne M. Medling, Prajval Shastri, Jaya Maithil, Preeti Kharb, Julie Banfield, Fergus Longbottom, Michael A. Dopita, Elise J. Hampton, Julia Scharwächter, Ralph Sutherland, Chichuan Jin, Ingyin Zaw, Bethan James, Stéphanie Juneau

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

46 Citations (Scopus)

Abstract

The most rapidly evolving regions of galaxies often display complex optical spectra with emission lines excited by massive stars, shocks and accretion on to supermassive black holes. Standard calibrations (such as for the star formation rate) cannot be applied to such mixed spectra. In this paper, we isolate the contributions of star formation, shock excitation and active galactic nucleus (AGN) activity to the emission line luminosities of individual spatially resolved regions across the central 3 × 3 kpc² region of the active barred spiral galaxy NGC 613. The star formation rate and AGN luminosity calculated from the decomposed emission line maps are in close agreement with independent estimates from data at other wavelengths. The star formation component traces the B-band stellar continuum emission, and the AGN component forms an ionization cone which is aligned with the nuclear radio jet. The optical line emission associated with shock excitation is cospatial with strong H₂ and [Fe II] emission and with regions of high ionized gas velocity dispersion (σ ≳ 100 km s^-1). The shock component also traces the outer boundary of the AGN ionization cone and may therefore be produced by outflowing material interacting with the surrounding interstellar medium. Our decomposition method makes it possible to determine the properties of star formation, shock excitation and AGN activity from optical spectra, without contamination from other ionization mechanisms.

Original language	English
Pages (from-to)	4974-4988
Number of pages	15
Journal	Monthly Notices of the Royal Astronomical Society
Volume	470
Issue number	4
DOIs	https://doi.org/10.1093/mnras/stx1559
Publication status	Published - Oct 2017

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Davies, R. L., Groves, B., Kewley, L. J., Medling, A. M., Shastri, P., Maithil, J., Kharb, P., Banfield, J., Longbottom, F., Dopita, M. A., Hampton, E. J., Scharwächter, J., Sutherland, R., Jin, C., Zaw, I., James, B., & Juneau, S. (2017). Dissecting galaxies: Separating star formation, shock excitation and AGN activity in the central region of NGC 613. Monthly Notices of the Royal Astronomical Society, 470(4), 4974-4988. https://doi.org/10.1093/mnras/stx1559

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title = "Dissecting galaxies: Separating star formation, shock excitation and AGN activity in the central region of NGC 613",

abstract = "The most rapidly evolving regions of galaxies often display complex optical spectra with emission lines excited by massive stars, shocks and accretion on to supermassive black holes. Standard calibrations (such as for the star formation rate) cannot be applied to such mixed spectra. In this paper, we isolate the contributions of star formation, shock excitation and active galactic nucleus (AGN) activity to the emission line luminosities of individual spatially resolved regions across the central 3 × 3 kpc2 region of the active barred spiral galaxy NGC 613. The star formation rate and AGN luminosity calculated from the decomposed emission line maps are in close agreement with independent estimates from data at other wavelengths. The star formation component traces the B-band stellar continuum emission, and the AGN component forms an ionization cone which is aligned with the nuclear radio jet. The optical line emission associated with shock excitation is cospatial with strong H2 and [Fe II] emission and with regions of high ionized gas velocity dispersion (σ ≳ 100 km s-1). The shock component also traces the outer boundary of the AGN ionization cone and may therefore be produced by outflowing material interacting with the surrounding interstellar medium. Our decomposition method makes it possible to determine the properties of star formation, shock excitation and AGN activity from optical spectra, without contamination from other ionization mechanisms.",

keywords = "Galaxies: ISM, Galaxies: Seyfert, Galaxies: evolution",

author = "Davies, {Rebecca L.} and Brent Groves and Kewley, {Lisa J.} and Medling, {Anne M.} and Prajval Shastri and Jaya Maithil and Preeti Kharb and Julie Banfield and Fergus Longbottom and Dopita, {Michael A.} and Hampton, {Elise J.} and Julia Scharw{\"a}chter and Ralph Sutherland and Chichuan Jin and Ingyin Zaw and Bethan James and St{\'e}phanie Juneau",

note = "Publisher Copyright: {\textcopyright} 2018 The Author(s).",

year = "2017",

month = oct,

doi = "10.1093/mnras/stx1559",

language = "English",

volume = "470",

pages = "4974--4988",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

publisher = "Oxford University Press ",

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Davies, RL, Groves, B, Kewley, LJ, Medling, AM, Shastri, P, Maithil, J, Kharb, P, Banfield, J, Longbottom, F, Dopita, MA, Hampton, EJ, Scharwächter, J, Sutherland, R, Jin, C, Zaw, I, James, B & Juneau, S 2017, 'Dissecting galaxies: Separating star formation, shock excitation and AGN activity in the central region of NGC 613', Monthly Notices of the Royal Astronomical Society, vol. 470, no. 4, pp. 4974-4988. https://doi.org/10.1093/mnras/stx1559

TY - JOUR

T1 - Dissecting galaxies

T2 - Separating star formation, shock excitation and AGN activity in the central region of NGC 613

AU - Davies, Rebecca L.

AU - Groves, Brent

AU - Kewley, Lisa J.

AU - Medling, Anne M.

AU - Shastri, Prajval

AU - Maithil, Jaya

AU - Kharb, Preeti

AU - Banfield, Julie

AU - Longbottom, Fergus

AU - Dopita, Michael A.

AU - Hampton, Elise J.

AU - Scharwächter, Julia

AU - Sutherland, Ralph

AU - Jin, Chichuan

AU - Zaw, Ingyin

AU - James, Bethan

AU - Juneau, Stéphanie

PY - 2017/10

Y1 - 2017/10

N2 - The most rapidly evolving regions of galaxies often display complex optical spectra with emission lines excited by massive stars, shocks and accretion on to supermassive black holes. Standard calibrations (such as for the star formation rate) cannot be applied to such mixed spectra. In this paper, we isolate the contributions of star formation, shock excitation and active galactic nucleus (AGN) activity to the emission line luminosities of individual spatially resolved regions across the central 3 × 3 kpc2 region of the active barred spiral galaxy NGC 613. The star formation rate and AGN luminosity calculated from the decomposed emission line maps are in close agreement with independent estimates from data at other wavelengths. The star formation component traces the B-band stellar continuum emission, and the AGN component forms an ionization cone which is aligned with the nuclear radio jet. The optical line emission associated with shock excitation is cospatial with strong H2 and [Fe II] emission and with regions of high ionized gas velocity dispersion (σ ≳ 100 km s-1). The shock component also traces the outer boundary of the AGN ionization cone and may therefore be produced by outflowing material interacting with the surrounding interstellar medium. Our decomposition method makes it possible to determine the properties of star formation, shock excitation and AGN activity from optical spectra, without contamination from other ionization mechanisms.

AB - The most rapidly evolving regions of galaxies often display complex optical spectra with emission lines excited by massive stars, shocks and accretion on to supermassive black holes. Standard calibrations (such as for the star formation rate) cannot be applied to such mixed spectra. In this paper, we isolate the contributions of star formation, shock excitation and active galactic nucleus (AGN) activity to the emission line luminosities of individual spatially resolved regions across the central 3 × 3 kpc2 region of the active barred spiral galaxy NGC 613. The star formation rate and AGN luminosity calculated from the decomposed emission line maps are in close agreement with independent estimates from data at other wavelengths. The star formation component traces the B-band stellar continuum emission, and the AGN component forms an ionization cone which is aligned with the nuclear radio jet. The optical line emission associated with shock excitation is cospatial with strong H2 and [Fe II] emission and with regions of high ionized gas velocity dispersion (σ ≳ 100 km s-1). The shock component also traces the outer boundary of the AGN ionization cone and may therefore be produced by outflowing material interacting with the surrounding interstellar medium. Our decomposition method makes it possible to determine the properties of star formation, shock excitation and AGN activity from optical spectra, without contamination from other ionization mechanisms.

KW - Galaxies: ISM

KW - Galaxies: Seyfert

KW - Galaxies: evolution

UR - http://www.scopus.com/inward/record.url?scp=85030180045&partnerID=8YFLogxK

U2 - 10.1093/mnras/stx1559

DO - 10.1093/mnras/stx1559

M3 - Article

SN - 0035-8711

VL - 470

SP - 4974

EP - 4988

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 4

ER -

Dissecting galaxies: Separating star formation, shock excitation and AGN activity in the central region of NGC 613

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