Double-peaked Ca II traces a relativistic broad-line region disk in NGC 4593

M. W. Ochmann; P. M. Weilbacher; M. A. Probst; W. Kollatschny; D. Chelouche; R. Chini; D. Grupe; M. Haas; S. Kaspi; S. Komossa

doi:10.1051/0004-6361/202554800

Double-peaked Ca II traces a relativistic broad-line region disk in NGC 4593

M. W. Ochmann, P. M. Weilbacher, M. A. Probst, W. Kollatschny, D. Chelouche, R. Chini, D. Grupe, M. Haas, S. Kaspi, S. Komossa

University of Haifa, Tel Aviv University

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

Abstract

Context. Double-peaked emission lines are observed in a small percentage of active galactic nuclei (AGN). These lines allow the determination of fundamental properties of the line-emitting region, known as the broad-line region (BLR). Aims. We investigated the structure and kinematics of the BLR in the nearby Seyfert galaxy NGC 4593 through an analysis of the near-infrared (NIR) line blend of CaIIλ8498,âÂ?Â? λ8542,âÂ?Â? λ8662, and OIλ8446 observed in a 2019 VLT/MUSE spectrum. Methods. We performed a detailed decomposition of the NIR CaII triplet and OIλ8446 blend, extracting clean profiles of CaIIλ8498,âÂ?Â? λ8542,âÂ?Â? λ8662, and OIλ8446. We then fitted CaIIλ8662 with a relativistic elliptical line-emitting accretion disk model. Results. The extracted line profiles are double-peaked with a full width at half maximum (FWHM) of âÂ? ¼3700 km s^{- 1} and exhibit a redward asymmetry with a red-to-blue peak ratio of 4:3. The CaII triplet lines have an intensity ratio of 1:1:1 and show no evidence of a central narrow or intermediate-width component. The profiles of CaII and OI are remarkably similar, suggesting a common region of origin. Given the 1:1:1 ratio of the CaII triplet, this region is likely a high-density emission zone, and the CaIIλ8662 profile is well described by a mildly eccentric, low-inclination relativistic line-emitting disk with minimal internal turbulence. The profile represents one of the clearest kinematic signatures of a relativistic disk observed in BLR emission lines to date. Conclusions. The double-peaked profiles of the NIR CaII triplet and OIλ8446 in NGC 4593 represent the first detection of double-peaked CaII and OIλ8446 in a nontransient AGN spectrum. The minimal intrinsic turbulence (the lowest value reported for an AGN emission line to date) and the absence of narrow or intermediate-width components in CaIIλ8662 make it a powerful diagnostic tool of BLR structure and kinematics. Further investigations of the profiles of CaII and OI in other AGN are recommended to better constrain BLR properties and the nature of the underlying accretion flow.

Original language	English
Article number	L5
Journal	Astronomy and Astrophysics
Volume	697
DOIs	https://doi.org/10.1051/0004-6361/202554800
State	Published - 1 May 2025

Keywords

Galaxies: Seyfert
Galaxies: active
Galaxies: nuclei
Quasars: emission lines
Quasars: individual: NGC 4593

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

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10.1051/0004-6361/202554800

https://www.aanda.org/articles/aa/pdf/forth/aa54800-25.pdf

Cite this

@article{a6e4db9d334c443fa037d73a7a53e863,

title = "Double-peaked Ca II traces a relativistic broad-line region disk in NGC 4593",

abstract = "Context. Double-peaked emission lines are observed in a small percentage of active galactic nuclei (AGN). These lines allow the determination of fundamental properties of the line-emitting region, known as the broad-line region (BLR). Aims. We investigated the structure and kinematics of the BLR in the nearby Seyfert galaxy NGC 4593 through an analysis of the near-infrared (NIR) line blend of CaIIλ8498,{\^a}{\^A}?{\^A}? λ8542,{\^a}{\^A}?{\^A}? λ8662, and OIλ8446 observed in a 2019 VLT/MUSE spectrum. Methods. We performed a detailed decomposition of the NIR CaII triplet and OIλ8446 blend, extracting clean profiles of CaIIλ8498,{\^a}{\^A}?{\^A}? λ8542,{\^a}{\^A}?{\^A}? λ8662, and OIλ8446. We then fitted CaIIλ8662 with a relativistic elliptical line-emitting accretion disk model. Results. The extracted line profiles are double-peaked with a full width at half maximum (FWHM) of {\^a}{\^A}? ¼3700 km s- 1 and exhibit a redward asymmetry with a red-to-blue peak ratio of 4:3. The CaII triplet lines have an intensity ratio of 1:1:1 and show no evidence of a central narrow or intermediate-width component. The profiles of CaII and OI are remarkably similar, suggesting a common region of origin. Given the 1:1:1 ratio of the CaII triplet, this region is likely a high-density emission zone, and the CaIIλ8662 profile is well described by a mildly eccentric, low-inclination relativistic line-emitting disk with minimal internal turbulence. The profile represents one of the clearest kinematic signatures of a relativistic disk observed in BLR emission lines to date. Conclusions. The double-peaked profiles of the NIR CaII triplet and OIλ8446 in NGC 4593 represent the first detection of double-peaked CaII and OIλ8446 in a nontransient AGN spectrum. The minimal intrinsic turbulence (the lowest value reported for an AGN emission line to date) and the absence of narrow or intermediate-width components in CaIIλ8662 make it a powerful diagnostic tool of BLR structure and kinematics. Further investigations of the profiles of CaII and OI in other AGN are recommended to better constrain BLR properties and the nature of the underlying accretion flow.",

keywords = "Galaxies: Seyfert, Galaxies: active, Galaxies: nuclei, Quasars: emission lines, Quasars: individual: NGC 4593",

author = "Ochmann, {M. W.} and Weilbacher, {P. M.} and Probst, {M. A.} and W. Kollatschny and D. Chelouche and R. Chini and D. Grupe and M. Haas and S. Kaspi and S. Komossa",

note = "Publisher Copyright: {\textcopyright} The Authors 2025.",

year = "2025",

month = may,

day = "1",

doi = "10.1051/0004-6361/202554800",

language = "الإنجليزيّة",

volume = "697",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

}

TY - JOUR

T1 - Double-peaked Ca II traces a relativistic broad-line region disk in NGC 4593

AU - Ochmann, M. W.

AU - Weilbacher, P. M.

AU - Probst, M. A.

AU - Kollatschny, W.

AU - Chelouche, D.

AU - Chini, R.

AU - Grupe, D.

AU - Haas, M.

AU - Kaspi, S.

AU - Komossa, S.

PY - 2025/5/1

Y1 - 2025/5/1

N2 - Context. Double-peaked emission lines are observed in a small percentage of active galactic nuclei (AGN). These lines allow the determination of fundamental properties of the line-emitting region, known as the broad-line region (BLR). Aims. We investigated the structure and kinematics of the BLR in the nearby Seyfert galaxy NGC 4593 through an analysis of the near-infrared (NIR) line blend of CaIIλ8498,âÂ?Â? λ8542,âÂ?Â? λ8662, and OIλ8446 observed in a 2019 VLT/MUSE spectrum. Methods. We performed a detailed decomposition of the NIR CaII triplet and OIλ8446 blend, extracting clean profiles of CaIIλ8498,âÂ?Â? λ8542,âÂ?Â? λ8662, and OIλ8446. We then fitted CaIIλ8662 with a relativistic elliptical line-emitting accretion disk model. Results. The extracted line profiles are double-peaked with a full width at half maximum (FWHM) of âÂ? ¼3700 km s- 1 and exhibit a redward asymmetry with a red-to-blue peak ratio of 4:3. The CaII triplet lines have an intensity ratio of 1:1:1 and show no evidence of a central narrow or intermediate-width component. The profiles of CaII and OI are remarkably similar, suggesting a common region of origin. Given the 1:1:1 ratio of the CaII triplet, this region is likely a high-density emission zone, and the CaIIλ8662 profile is well described by a mildly eccentric, low-inclination relativistic line-emitting disk with minimal internal turbulence. The profile represents one of the clearest kinematic signatures of a relativistic disk observed in BLR emission lines to date. Conclusions. The double-peaked profiles of the NIR CaII triplet and OIλ8446 in NGC 4593 represent the first detection of double-peaked CaII and OIλ8446 in a nontransient AGN spectrum. The minimal intrinsic turbulence (the lowest value reported for an AGN emission line to date) and the absence of narrow or intermediate-width components in CaIIλ8662 make it a powerful diagnostic tool of BLR structure and kinematics. Further investigations of the profiles of CaII and OI in other AGN are recommended to better constrain BLR properties and the nature of the underlying accretion flow.

AB - Context. Double-peaked emission lines are observed in a small percentage of active galactic nuclei (AGN). These lines allow the determination of fundamental properties of the line-emitting region, known as the broad-line region (BLR). Aims. We investigated the structure and kinematics of the BLR in the nearby Seyfert galaxy NGC 4593 through an analysis of the near-infrared (NIR) line blend of CaIIλ8498,âÂ?Â? λ8542,âÂ?Â? λ8662, and OIλ8446 observed in a 2019 VLT/MUSE spectrum. Methods. We performed a detailed decomposition of the NIR CaII triplet and OIλ8446 blend, extracting clean profiles of CaIIλ8498,âÂ?Â? λ8542,âÂ?Â? λ8662, and OIλ8446. We then fitted CaIIλ8662 with a relativistic elliptical line-emitting accretion disk model. Results. The extracted line profiles are double-peaked with a full width at half maximum (FWHM) of âÂ? ¼3700 km s- 1 and exhibit a redward asymmetry with a red-to-blue peak ratio of 4:3. The CaII triplet lines have an intensity ratio of 1:1:1 and show no evidence of a central narrow or intermediate-width component. The profiles of CaII and OI are remarkably similar, suggesting a common region of origin. Given the 1:1:1 ratio of the CaII triplet, this region is likely a high-density emission zone, and the CaIIλ8662 profile is well described by a mildly eccentric, low-inclination relativistic line-emitting disk with minimal internal turbulence. The profile represents one of the clearest kinematic signatures of a relativistic disk observed in BLR emission lines to date. Conclusions. The double-peaked profiles of the NIR CaII triplet and OIλ8446 in NGC 4593 represent the first detection of double-peaked CaII and OIλ8446 in a nontransient AGN spectrum. The minimal intrinsic turbulence (the lowest value reported for an AGN emission line to date) and the absence of narrow or intermediate-width components in CaIIλ8662 make it a powerful diagnostic tool of BLR structure and kinematics. Further investigations of the profiles of CaII and OI in other AGN are recommended to better constrain BLR properties and the nature of the underlying accretion flow.

KW - Galaxies: Seyfert

KW - Galaxies: active

KW - Galaxies: nuclei

KW - Quasars: emission lines

KW - Quasars: individual: NGC 4593

UR - http://www.scopus.com/inward/record.url?scp=105005513952&partnerID=8YFLogxK

U2 - 10.1051/0004-6361/202554800

DO - 10.1051/0004-6361/202554800

M3 - مقالة

SN - 0004-6361

VL - 697

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - L5

ER -

Double-peaked Ca II traces a relativistic broad-line region disk in NGC 4593

Abstract

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