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Space Telescope and Optical Reverberation Mapping Project. IX. Velocity–Delay Maps for Broad Emission Lines in NGC 5548

Horne, Keith; Rosa, G. De; Peterson, B.M.; Barth, A.J.; Ely, J.; Fausnaugh, M.M.; Kriss, G.A.; Pei, L.; Bentz, M.C.; Cackett, E.M.; Edelson, R.; Eracleous, M.; Goad, M.R.; Grier, C.J.; Kaastra, J.; Kochanek, C.S.; Krongold, Y.; Mathur, S.; Netzer, H.; Proga, D.; Tejos, N.; Vestergaard, M.; Villforth, C.; Adams, S.M.; Anderson, M.D.; Arévalo, P.; Beatty, TG.; Bennert, V.N.; Bigley, A.; Bisogni, S.; Borman, G.A.; Boroson, T.A.; Bottorff, M.C.; Brandt, W.N.; Breeveld, A.A.; Brotherton, M.; Brown, J.E.; Brown, J.S.; Canalizo, G.; Carini, M.T.; Clubb, K.I.; Comerford, J.M.; Corsini, E.M.; Crenshaw, D.M.; Croft, S.; Croxall, K.V.; Bontà, E. Dalla; Deason, A.J.; Dehghanian, M.; Lorenzo-Cáceres, A. De; Denney, K.D.; Dietrich, M.; Done, C.; Efimova, N.V.; Evans, P.A.; Ferland, G.J.; Filippenko, A.V.; Flatland, K.; Fox, O.D.; Gardner, E.; Gates, E.L.; Gehrels, N.; Geier, S.; Gelbord, J.M.; Gonzalez, L.; Gorjian, V.; Greene, J.E.; Grupe, D.; Gupta, A.; Hall, P.B.; Henderson, C.B.; Hicks, S.; Holm...

Space Telescope and Optical Reverberation Mapping Project. IX. Velocity–Delay Maps for Broad Emission Lines in NGC 5548 Thumbnail


Keith Horne

G. De Rosa

B.M. Peterson

A.J. Barth

J. Ely

M.M. Fausnaugh

G.A. Kriss

L. Pei

M.C. Bentz

E.M. Cackett

R. Edelson

M. Eracleous

M.R. Goad

C.J. Grier

J. Kaastra

C.S. Kochanek

Y. Krongold

S. Mathur

H. Netzer

D. Proga

N. Tejos

M. Vestergaard

C. Villforth

S.M. Adams

M.D. Anderson

P. Arévalo

TG. Beatty

V.N. Bennert

A. Bigley

S. Bisogni

G.A. Borman

T.A. Boroson

M.C. Bottorff

W.N. Brandt

A.A. Breeveld

M. Brotherton

J.E. Brown

J.S. Brown

G. Canalizo

M.T. Carini

K.I. Clubb

J.M. Comerford

E.M. Corsini

D.M. Crenshaw

S. Croft

K.V. Croxall

E. Dalla Bontà

M. Dehghanian

A. De Lorenzo-Cáceres

K.D. Denney

M. Dietrich

N.V. Efimova

P.A. Evans

G.J. Ferland

A.V. Filippenko

K. Flatland

O.D. Fox

E. Gardner

E.L. Gates

N. Gehrels

S. Geier

J.M. Gelbord

L. Gonzalez

V. Gorjian

J.E. Greene

D. Grupe

A. Gupta

P.B. Hall

C.B. Henderson

S. Hicks

E. Holmbeck

T.W.-S. Holoien

T. Hutchison

M. Im

J.J. Jensen

C.A. Johnson

M.D. Joner

J. Jones

S. Kaspi

P.L. Kelly

J.A. Kennea

M. Kim

S. Kim

S.C. Kim

A. King

S.A. Klimanov

K.T. Korista

M.W. Lau

J.C. Lee

D.C. Leonard

Miao Li

P. Lira

C. Lochhaas

Zhiyuan Ma

F. MacInnis

M.A. Malkan

E.R. Manne-Nicholas

J.C. Mauerhan

R. McGurk

I.M. McHardy

C. Montuori

L. Morelli

A. Mosquera

D. Mudd

F. Müller–Sánchez

S.V. Nazarov

R.P. Norris

J.A. Nousek

M.L. Nguyen

P. Ochner

D.N. Okhmat

A. Pancoast

I. Papadakis

J.R. Parks

M.T. Penny

A. Pizzella

R.W. Pogge

R. Poleski

J.-U. Pott

S.E. Rafter

H.-W. Rix

J. Runnoe

D.A. Saylor

J.S. Schimoia

K. Schnülle

B. Scott

S.G. Sergeev

B.J. Shappee

I. Shivvers

M. Siegel

G.V. Simonian

A. Siviero

A. Skielboe

G. Somers

M. Spencer

D. Starkey

D.J. Stevens

H.-I. Sung

J. Tayar

T. Treu

C.S. Turner

P. Uttley

J. Van Saders

L. Vican

S. Villanueva

Y. Weiss

J.-H. Woo

H. Yan

S. Young

H. Yuk

W. Zheng

W. Zhu

Y. Zu


In this contribution, we achieve the primary goal of the active galactic nucleus (AGN) STORM campaign by recovering velocity–delay maps for the prominent broad emission lines (Lyα, C iv, He ii, and Hβ) in the spectrum of NGC 5548. These are the most detailed velocity–delay maps ever obtained for an AGN, providing unprecedented information on the geometry, ionization structure, and kinematics of the broad-line region. Virial envelopes enclosing the emission-line responses show that the reverberating gas is bound to the black hole. A stratified ionization structure is evident. The He ii response inside 5–10 lt-day has a broad single-peaked velocity profile. The Lyα, C iv, and Hβ responses extend from inside 2 to outside 20 lt-day, with double peaks at ±2500 km s−1 in the 10–20 lt-day delay range. An incomplete ellipse in the velocity–delay plane is evident in Hβ. We interpret the maps in terms of a Keplerian disk with a well-defined outer rim at R = 20 lt-day. The far-side response is weaker than that from the near side. The line-center delay $\tau =(R/c)(1-\sin i)\approx 5$ days gives the inclination i ≈ 45°. The inferred black hole mass is MBH ≈ 7 × 107 M⊙. In addition to reverberations, the fit residuals confirm that emission-line fluxes are depressed during the "BLR Holiday" identified in previous work. Moreover, a helical "Barber-Pole" pattern, with stripes moving from red to blue across the C iv and Lyα line profiles, suggests azimuthal structure rotating with a 2 yr period that may represent precession or orbital motion of inner-disk structures casting shadows on the emission-line region farther out.


Horne, K., Rosa, G. D., Peterson, B., Barth, A., Ely, J., Fausnaugh, M., …Zu, Y. (2021). Space Telescope and Optical Reverberation Mapping Project. IX. Velocity–Delay Maps for Broad Emission Lines in NGC 5548. Astrophysical Journal, 907(2), Article 76.

Journal Article Type Article
Acceptance Date Nov 25, 2020
Online Publication Date Feb 1, 2021
Publication Date Feb 1, 2021
Deposit Date Jul 22, 2021
Publicly Available Date Feb 1, 2022
Journal Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 907
Issue 2
Article Number 76
Related Public URLs


Accepted Journal Article (4.2 Mb)

Copyright Statement
This is an author-created, un-copyedited version of an article published in The Astrophysical Journal. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version<br /> derived from it. The Version of Record is available online at

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