The University of Southampton
University of Southampton Institutional Repository

NuSTAR spectroscopy of multi-component x-ray reflection from NGC 1068

NuSTAR spectroscopy of multi-component x-ray reflection from NGC 1068
NuSTAR spectroscopy of multi-component x-ray reflection from NGC 1068
We report on high-energy X-ray observations of the Compton-thick Seyfert 2 galaxy NGC 1068 with NuSTAR, which provide the best constraints to date on its >10 keV spectral shape. The NuSTAR data are consistent with those from past and current instruments to within cross-calibration uncertainties, and we find no strong continuum or line variability over the past two decades, which is in line with its X-ray classification as a reflection-dominated Compton-thick active galactic nucleus. The combined NuSTAR, Chandra, XMM-Newton, and Swift BAT spectral data set offers new insights into the complex secondary emission seen instead of the completely obscured transmitted nuclear continuum. The critical combination of the high signal-to-noise NuSTAR data and the decomposition of the nuclear and extranuclear emission with Chandra allow us to break several model degeneracies and greatly aid physical interpretation. When modeled as a monolithic (i.e., a single NH) reflector, none of the common Compton reflection models are able to match the neutral fluorescence lines and broad spectral shape of the Compton reflection hump without requiring unrealistic physical parameters (e.g., large Fe overabundances, inconsistent viewing angles, or poor fits to the spatially resolved spectra). A multi-component reflector with three distinct column densities (e.g., with best-fit values of NH of 1.4 × 1023, 5.0 × 1024, and 1025 cm-2) provides a more reasonable fit to the spectral lines and Compton hump, with near-solar Fe abundances. In this model, the higher NH component provides the bulk of the flux to the Compton hump, while the lower NH component produces much of the line emission, effectively decoupling two key features of Compton reflection. We find that ≈30% of the neutral Fe Kα line flux arises from >2" (≈140 pc) and is clearly extended, implying that a significant fraction (and perhaps most) of the <10 keV reflected component arises from regions well outside a parsec-scale torus. These results likely have ramifications for the interpretation of Compton-thick spectra from observations with poorer signal-to-noise and/or more distant objects.
galaxies, active, individual, NGC 1068, X-rays
1538-4357
1-24
Bauer, F.E.
4090334d-93b3-4fd4-83bf-3c65385dce47
Arevao, P.
da0d86aa-2402-4b38-9fb5-8c1f83d24d30
Walton, D.J.
a1a36b18-a77b-48e8-8665-45bbef0c7bd1
Koss, M.J.
c915109e-45f4-4d05-8bcd-7849d979f68e
Puccetti, S.
c13be5d0-a887-45be-86a1-2106b1d65817
Gandhi, P.
5bc3b5af-42b0-4dd8-8f1f-f74048d4d4a9
Stern, D.
a573010b-ca8e-4018-b0f5-4621657713b3
Alexander, D.M.
f3dc82b1-0fc8-4fa9-985d-b0d9d8f22acb
Balokovic, M.
14260868-dc7d-4ef8-a074-364b8d11e405
Boggs, S.E.
0d2453ab-f518-4f55-92d7-dd8a4f0572d6
Brandt, W.N.
2ccd8265-d819-4b7a-8ec8-ced4bfb7baeb
Brightman, M.
eb110ae1-9a2c-4968-b9ef-e7955feba535
Chstensen, D.E.
a5ce1d72-ed6e-4b97-bfa2-ccfb4ab52be1
Comastri, A.
8068001f-aff5-4dcd-906c-1c91af4bad97
Craig, W.W.
a15d85e8-3d7c-4bf5-895a-6b754550be47
Del Moro, A.
933e7c60-b84c-4311-ad21-1edf882b3636
Hailey, C.J.
21767629-445e-4929-99cc-64d9344b4cbb
Harrison, F.A.
b71f286a-75db-46ef-8953-bd41865e74bc
Hickox, R.
eba135fd-d4eb-4d2d-8b5f-37904a9b6d3d
Luo, B.
f713f72d-2eee-43f8-bb72-078cdc17aeb4
Markwardt, C.B.
2087ae8b-da7d-436f-8f58-e4d3785a89f1
Marinucci, A.
fdc8f93c-7e91-4c7d-b8c7-50e774337f6e
Matt, G.
790376ef-1ca7-4eb5-b46e-3514c9152665
Rigby, J.R.
34cbd46a-7eef-4341-9b02-aec9f3cf6bf2
River, E.
6596d3b1-ee2a-4101-8aff-6e307c506ea9
Saez, C.
d6d0c2b1-400b-46e4-b789-19b5f2bd6061
Treister, E.
77355954-69e7-4887-82be-9f54bab406bc
Urry, C.M.
506a7d1f-d721-4b3a-919d-f5d47647f1ea
Zhang, W.W.
ce873dd4-1b5f-4982-896a-f06fca99fb1b
Bauer, F.E.
4090334d-93b3-4fd4-83bf-3c65385dce47
Arevao, P.
da0d86aa-2402-4b38-9fb5-8c1f83d24d30
Walton, D.J.
a1a36b18-a77b-48e8-8665-45bbef0c7bd1
Koss, M.J.
c915109e-45f4-4d05-8bcd-7849d979f68e
Puccetti, S.
c13be5d0-a887-45be-86a1-2106b1d65817
Gandhi, P.
5bc3b5af-42b0-4dd8-8f1f-f74048d4d4a9
Stern, D.
a573010b-ca8e-4018-b0f5-4621657713b3
Alexander, D.M.
f3dc82b1-0fc8-4fa9-985d-b0d9d8f22acb
Balokovic, M.
14260868-dc7d-4ef8-a074-364b8d11e405
Boggs, S.E.
0d2453ab-f518-4f55-92d7-dd8a4f0572d6
Brandt, W.N.
2ccd8265-d819-4b7a-8ec8-ced4bfb7baeb
Brightman, M.
eb110ae1-9a2c-4968-b9ef-e7955feba535
Chstensen, D.E.
a5ce1d72-ed6e-4b97-bfa2-ccfb4ab52be1
Comastri, A.
8068001f-aff5-4dcd-906c-1c91af4bad97
Craig, W.W.
a15d85e8-3d7c-4bf5-895a-6b754550be47
Del Moro, A.
933e7c60-b84c-4311-ad21-1edf882b3636
Hailey, C.J.
21767629-445e-4929-99cc-64d9344b4cbb
Harrison, F.A.
b71f286a-75db-46ef-8953-bd41865e74bc
Hickox, R.
eba135fd-d4eb-4d2d-8b5f-37904a9b6d3d
Luo, B.
f713f72d-2eee-43f8-bb72-078cdc17aeb4
Markwardt, C.B.
2087ae8b-da7d-436f-8f58-e4d3785a89f1
Marinucci, A.
fdc8f93c-7e91-4c7d-b8c7-50e774337f6e
Matt, G.
790376ef-1ca7-4eb5-b46e-3514c9152665
Rigby, J.R.
34cbd46a-7eef-4341-9b02-aec9f3cf6bf2
River, E.
6596d3b1-ee2a-4101-8aff-6e307c506ea9
Saez, C.
d6d0c2b1-400b-46e4-b789-19b5f2bd6061
Treister, E.
77355954-69e7-4887-82be-9f54bab406bc
Urry, C.M.
506a7d1f-d721-4b3a-919d-f5d47647f1ea
Zhang, W.W.
ce873dd4-1b5f-4982-896a-f06fca99fb1b

Bauer, F.E., Arevao, P., Walton, D.J., Koss, M.J., Puccetti, S., Gandhi, P., Stern, D., Alexander, D.M., Balokovic, M., Boggs, S.E., Brandt, W.N., Brightman, M., Chstensen, D.E., Comastri, A., Craig, W.W., Del Moro, A., Hailey, C.J., Harrison, F.A., Hickox, R., Luo, B., Markwardt, C.B., Marinucci, A., Matt, G., Rigby, J.R., River, E., Saez, C., Treister, E., Urry, C.M. and Zhang, W.W. (2015) NuSTAR spectroscopy of multi-component x-ray reflection from NGC 1068. The Astrophysical Journal, 812 (116), 1-24. (doi:10.1088/0004-637X/812/2/116).

Record type: Article

Abstract

We report on high-energy X-ray observations of the Compton-thick Seyfert 2 galaxy NGC 1068 with NuSTAR, which provide the best constraints to date on its >10 keV spectral shape. The NuSTAR data are consistent with those from past and current instruments to within cross-calibration uncertainties, and we find no strong continuum or line variability over the past two decades, which is in line with its X-ray classification as a reflection-dominated Compton-thick active galactic nucleus. The combined NuSTAR, Chandra, XMM-Newton, and Swift BAT spectral data set offers new insights into the complex secondary emission seen instead of the completely obscured transmitted nuclear continuum. The critical combination of the high signal-to-noise NuSTAR data and the decomposition of the nuclear and extranuclear emission with Chandra allow us to break several model degeneracies and greatly aid physical interpretation. When modeled as a monolithic (i.e., a single NH) reflector, none of the common Compton reflection models are able to match the neutral fluorescence lines and broad spectral shape of the Compton reflection hump without requiring unrealistic physical parameters (e.g., large Fe overabundances, inconsistent viewing angles, or poor fits to the spatially resolved spectra). A multi-component reflector with three distinct column densities (e.g., with best-fit values of NH of 1.4 × 1023, 5.0 × 1024, and 1025 cm-2) provides a more reasonable fit to the spectral lines and Compton hump, with near-solar Fe abundances. In this model, the higher NH component provides the bulk of the flux to the Compton hump, while the lower NH component produces much of the line emission, effectively decoupling two key features of Compton reflection. We find that ≈30% of the neutral Fe Kα line flux arises from >2" (≈140 pc) and is clearly extended, implying that a significant fraction (and perhaps most) of the <10 keV reflected component arises from regions well outside a parsec-scale torus. These results likely have ramifications for the interpretation of Compton-thick spectra from observations with poorer signal-to-noise and/or more distant objects.

Full text not available from this repository.

More information

Accepted/In Press date: 8 September 2015
Published date: 14 October 2015
Keywords: galaxies, active, individual, NGC 1068, X-rays
Organisations: Astronomy Group

Identifiers

Local EPrints ID: 400042
URI: https://eprints.soton.ac.uk/id/eprint/400042
ISSN: 1538-4357
PURE UUID: 44b10fbe-1f6b-4839-a5f0-b785039e5cfb
ORCID for P. Gandhi: ORCID iD orcid.org/0000-0003-3105-2615

Catalogue record

Date deposited: 08 Sep 2016 09:40
Last modified: 19 Feb 2019 01:30

Export record

Altmetrics

Contributors

Author: F.E. Bauer
Author: P. Arevao
Author: D.J. Walton
Author: M.J. Koss
Author: S. Puccetti
Author: P. Gandhi ORCID iD
Author: D. Stern
Author: D.M. Alexander
Author: M. Balokovic
Author: S.E. Boggs
Author: W.N. Brandt
Author: M. Brightman
Author: D.E. Chstensen
Author: A. Comastri
Author: W.W. Craig
Author: A. Del Moro
Author: C.J. Hailey
Author: F.A. Harrison
Author: R. Hickox
Author: B. Luo
Author: C.B. Markwardt
Author: A. Marinucci
Author: G. Matt
Author: J.R. Rigby
Author: E. River
Author: C. Saez
Author: E. Treister
Author: C.M. Urry
Author: W.W. Zhang

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of https://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×