---
OA_place: publisher
OA_type: diamond
PlanS_conform: '1'
_id: '20686'
abstract:
- lang: eng
text: Emission from two massive black holes (MBHs) bound in a close binary is expected
to be modulated by different processes, such as the Doppler boost due to the orbital
motion, accretion rate variability generated by the interaction with a circumbinary
disc, and binary gravitational self-lensing. When the binary is compact enough,
the two black holes are thought to be surrounded by a common broad-line region
that reprocesses the impinging periodically varying ionising flux, creating broad
emission lines with variable line shapes. Therefore, the study of broad emission
line variability through multi-epoch spectroscopic campaigns is of paramount importance
for the unambiguous identification of a binary. In this work, we study the response
of a disc-like broad-line region to the Doppler-boosted ionising flux emitted
by sub-milliparsec MBH binaries on a circular orbit and compare it with the response
of a broad-line region illuminated by a single MBH with a periodically but isotropically
varying intrinsic luminosity. We show that in the binary case, the time lags of
the blue and red wings of the broad emission lines, arising from diametrically
opposite sides of the circumbinary disc, are out of phase by half of the binary’s
orbital period, as they each respond to the periodic ‘lighthouse’ modulation from
the binary’s continuum emission. This asymmetric time lag represents a new binary
signature that cannot be mimicked by a single MBH.
acknowledgement: MD acknowledge funding from MIUR under the grant PRIN 2017-MB8AEZ,
and financial support from ICSC – Centro Nazionale di Ricerca in High Performance
Computing, Big Data and Quantum Computing, funded by European Union – NextGenerationEU.
This study is supported by the Italian Ministry for Research and University (MUR)
under Grant ‘Progetto Dipartimenti di Eccellenza 2023-2027’ (BiCoQ). FR acknowledges
the support from the Next Generation EU funds within the National Recovery and Resilience
Plan (PNRR), Mission 4 – Education and Research, Component 2 – From Research to
Business (M4C2), Investment Line 3.1 – Strengthening and creation of Research Infrastructures,
Project IR0000012 – CTA+ – Cherenkov Telescope Array Plus. DJD acknowledges support
from the Danish Independent Research Fund through Sapere Aude Starting Grant No.
121587 ZH acknowledges support from NSF grant AST-2006176 and NASA grants 80NSSC22K0822
and 80NSSC24K0440.
article_number: A165
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Lorenzo
full_name: Bertassi, Lorenzo
last_name: Bertassi
- first_name: Erika
full_name: Sottocorno, Erika
last_name: Sottocorno
- first_name: Fabio
full_name: Rigamonti, Fabio
last_name: Rigamonti
- first_name: Daniel
full_name: D’Orazio, Daniel
last_name: D’Orazio
- first_name: Michael
full_name: Eracleous, Michael
last_name: Eracleous
- first_name: Zoltán
full_name: Haiman, Zoltán
id: 7c006e8c-cc0d-11ee-8322-cb904ef76f36
last_name: Haiman
orcid: 0000-0003-3633-5403
- first_name: Massimo
full_name: Dotti, Massimo
last_name: Dotti
citation:
ama: Bertassi L, Sottocorno E, Rigamonti F, et al. Testing compact massive black
hole binary candidates through multi-epoch spectroscopy. Astronomy & Astrophysics.
2025;702. doi:10.1051/0004-6361/202554574
apa: Bertassi, L., Sottocorno, E., Rigamonti, F., D’Orazio, D., Eracleous, M., Haiman,
Z., & Dotti, M. (2025). Testing compact massive black hole binary candidates
through multi-epoch spectroscopy. Astronomy & Astrophysics. EDP Sciences.
https://doi.org/10.1051/0004-6361/202554574
chicago: Bertassi, Lorenzo, Erika Sottocorno, Fabio Rigamonti, Daniel D’Orazio,
Michael Eracleous, Zoltán Haiman, and Massimo Dotti. “Testing Compact Massive
Black Hole Binary Candidates through Multi-Epoch Spectroscopy.” Astronomy &
Astrophysics. EDP Sciences, 2025. https://doi.org/10.1051/0004-6361/202554574.
ieee: L. Bertassi et al., “Testing compact massive black hole binary candidates
through multi-epoch spectroscopy,” Astronomy & Astrophysics, vol. 702.
EDP Sciences, 2025.
ista: Bertassi L, Sottocorno E, Rigamonti F, D’Orazio D, Eracleous M, Haiman Z,
Dotti M. 2025. Testing compact massive black hole binary candidates through multi-epoch
spectroscopy. Astronomy & Astrophysics. 702, A165.
mla: Bertassi, Lorenzo, et al. “Testing Compact Massive Black Hole Binary Candidates
through Multi-Epoch Spectroscopy.” Astronomy & Astrophysics, vol. 702,
A165, EDP Sciences, 2025, doi:10.1051/0004-6361/202554574.
short: L. Bertassi, E. Sottocorno, F. Rigamonti, D. D’Orazio, M. Eracleous, Z. Haiman,
M. Dotti, Astronomy & Astrophysics 702 (2025).
date_created: 2025-11-24T14:23:22Z
date_published: 2025-10-20T00:00:00Z
date_updated: 2025-12-01T15:31:55Z
day: '20'
ddc:
- '520'
department:
- _id: ZoHa
doi: 10.1051/0004-6361/202554574
external_id:
arxiv:
- '2504.06349'
isi:
- '001597841900015'
file:
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checksum: dbaf156cb6684bf5c3f5fb76fc890d5a
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creator: dernst
date_created: 2025-11-25T12:56:18Z
date_updated: 2025-11-25T12:56:18Z
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has_accepted_license: '1'
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language:
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month: '10'
oa: 1
oa_version: Published Version
publication: Astronomy & Astrophysics
publication_identifier:
eissn:
- 1432-0746
issn:
- 0004-6361
publication_status: published
publisher: EDP Sciences
quality_controlled: '1'
scopus_import: '1'
status: public
title: Testing compact massive black hole binary candidates through multi-epoch spectroscopy
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 702
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...