Time evolution of Mg <sc>II</sc> in SDSS J2320+0024: Implications for a subparsec binary supermassive black hole system

被引：0

作者：

Fatovic, Marta ^{[1
,2
,3
]}

Ilic, Dragana ^{[4
,5
]}

Kovacevic, Andjelka B. ^{[4
,6
]}

Palaversa, Lovro ^{[2
]}

Simic, Sasa ^{[7
]}

Popovic, Luka C. ^{[4
,6
,8
]}

Thanjavur, Karun ^{[9
]}

Razim, Oleksandra ^{[2
]}

Ivezic, Zeljko ^{[10
,11
]}

Yue, Minghao ^{[12
,13
]}

Fan, Xiaohui ^{[13
]}

机构：

[1] Univ Napoli Federico II, Dipartimento Fis Ettore Pancini, Via Cintia, I-80126 Naples, Italy

[2] Rudjer Boskovic Inst, Bijenicka Cesta 54, Zagreb 10000, Croatia

[3] INAF Osservatorio Astron Capodimonte, Via Moiariello 16, I-80131 Naples, Italy

[4] Univ Belgrade, Fac Math, Dept Astron, Studentski Trg 16, Belgrade 11000, Serbia

[5] Univ Hamburg, Hamburger Sternwarte, Gojenbergsweg 112, D-21029 Hamburg, Germany

[6] Chinese Acad Sci, Inst High Energy Phys, Key Lab Particle Astrophys, 19B Yuquan Rd, Beijing 100049, Peoples R China

[7] Univ Kragujevac, Fac Sci, Radoja Domanovica 12, Kragujevac 34000, Serbia

[8] Astron Observ, Volgina 7, Belgrade 11060, Serbia

[9] Univ Victoria, Dept Phys & Astron, 3800 Finnerty Rd, Victoria, BC V8P 5C2, Canada

[10] Univ Washington, Dept Astron, 3910 15th Ave NE, Seattle, WA 98195 USA

[11] Univ Washington, DiRAC Inst, 3910 15th Ave NE, Seattle, WA 98195 USA

[12] MIT, Kavli Inst Astrophys & Space Res, 77 Massachusetts Ave, Cambridge, MA 02139 USA

[13] Univ Arizona, Steward Observ, 933 North Cherry Ave, Tucson, AZ 85721 USA

来源：

ASTRONOMY & ASTROPHYSICS | 2025年 / 695卷

关键词：

line: profiles; quasars: emission lines; quasars: supermassive black holes; quasars: individual: SDSS J2320+0024; DIGITAL SKY SURVEY; ACTIVE GALACTIC NUCLEUS; QUASI-PERIODIC OSCILLATION; EMISSION-LINE PROFILES; SURVEY STRIPE 82; LIGHT CURVES; VARIABILITY; CANDIDATES; SEARCH; REGION;

D O I：

10.1051/0004-6361/202453600

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

Context. We present results from our spectroscopic follow-up of SDSS J2320+0024, a candidate binary supermassive black hole (SMBH) with a suspected subparsec separation, identified by a 278-day periodicity observed in its multiband optical light curves. Such systems serve as a crucial link between binaries with long periods (tens of years), which are influenced by tidal forces with minimal gravitational wave damping, and ultra-short-period binaries (<= order of days), which are dominated by gravitational wave-driven inspiral. Aims. We investigated the dramatic variability in the complex Mg II emission line profile with the aim of testing the alignments of the observed photometric light curves and the spectroscopic signatures in the context of the binary SMBH system. Methods. We extracted the pure broad Mg II line from newly obtained Gemini and Magellan spectra and measured the emission line parameters to determine the fundamental dynamical parameters of the SMBH's binary system. We adopted the PoSKI subparsec binary SMBH model, which includes a broad-line region around a less massive component and a circumbinary broad-line region, to interpret the observed variability in the spectral profile. Results. We find that the Mg II broad-line profile has a distinctive complex shape, with asymmetry and two peaks, which has varied across recent and archival observations. The temporal variability of the Mg II line profile may be associated with emission from the binary SMBH system, whose components have masses M-1 = 2 x 10(7) M-circle dot and M-2 = 2 x 10(8) M-circle dot and eccentricity e = 0.1. We discuss other plausible physical interpretations. With a total estimated mass of similar to 10(9) M-circle dot and a sub-annual orbital period, this system may be a rare example of a high-mass compact SMBH binary candidate and, thus, should be part of further investigations of the evolution of binary systems. This study highlights the synergies between spectroscopic follow-up and future massive time-domain photometric surveys, such as the Vera C. Rubin Observatory Legacy Survey of Space and Time.

引用

页数：9