Eccentric Minidisks in Accreting Binaries

Westernacher-Schneider, John Ryan; Zrake, Jonathan; MacFadyen, Andrew; Haiman, Zoltán

doi:10.3847/1538-4357/ad1a17

Cited by 8 publications

(2 citation statements)

References 78 publications

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“…The general schema of this project is flexible enough to incorporate other variability models in future work, like the continuous-time autoregressive moving average models (Kelly et al 2014) and the damped harmonic oscillator model (Yu et al 2022). Future work can also include a more detailed consideration of the differences between accretion disks around single quasars with the circumbinary disks and mini-disks in binary quasars (Artymowicz & Lubow 1996;MacFadyen & Milosavljević 2008;Westernacher-Schneider et al 2024).…”

Section: Variability Modelmentioning

confidence: 99%

Reliable Identification of Binary Supermassive Black Holes from Rubin Observatory Time-domain Monitoring

Davis,

Grace,

Trump

et al. 2024

ApJ

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Periodic signatures in time-domain observations of quasars have been used to search for binary supermassive black holes (SMBHs). These searches, across existing time-domain surveys, have produced several hundred candidates. The general stochastic variability of quasars, however, can masquerade as a false-positive periodic signal, especially when monitoring cadence and duration are limited. In this work, we predict the detectability of binary SMBHs in the upcoming Rubin Observatory Legacy Survey of Space and Time (LSST). We apply computationally inexpensive sinusoidal curve fits to millions of simulated LSST Deep Drilling Field light curves of both single, isolated quasars and binary quasars. The period and phase of simulated binary signals can generally be disentangled from quasar variability. Binary amplitude is overestimated and poorly recovered for two-thirds of potential binaries due to quasar accretion variability. Quasars with strong intrinsic variability can obscure a binary signal too much for recovery. We also find that the most luminous quasars mimic current binary candidate light curves and their properties: The false-positive rates are 60% for these quasars. The reliable recovery of binary period and phase for a wide range of input binary LSST light curves is promising for multi-messenger characterization of binary SMBHs. However, pure electromagnetic detections of binaries using photometric periodicity with amplitude greater than 0.1 mag will result in samples that are overwhelmed by false positives. This paper represents an important and computationally inexpensive way forward for understanding the true and false-positive rates for binary candidates identified by Rubin.

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Section: Variability Modelmentioning

confidence: 99%

Reliable Identification of Binary Supermassive Black Holes from Rubin Observatory Time-domain Monitoring

Davis,

Grace,

Trump

et al. 2024

ApJ

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“…Sailfish is a GPUaccelerated version of Mara3 that also includes post-processing modules to synthesize light curves of thermal disk emission. It is the code that was used in Westernacher-Schneider et al (2022), Major Krauth et al (2023), and Westernacher-Schneider et al (2024. Sailfish is very fast (10 9 zone updates per second for this problem on an A100 GPU), and it runs efficiently on multi-GPU nodes.…”

Section: A6 Mara3 and Sailfishmentioning

confidence: 99%

The Santa Barbara Binary−disk Code Comparison

Duffell,

Dittmann,

D’Orazio

et al. 2024

ApJ

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We have performed numerical calculations of a binary interacting with a gas disk, using 11 different numerical methods and a standard binary−disk setup. The goal of this study is to determine whether all codes agree on a numerically converged solution and to determine the necessary resolution for convergence and the number of binary orbits that must be computed to reach an agreed-upon relaxed state of the binary−disk system. We find that all codes can agree on a converged solution (depending on the diagnostic being measured). The zone spacing required for most codes to reach a converged measurement of the torques applied to the binary by the disk is roughly 1% of the binary separation in the vicinity of the binary components. For our disk model to reach a relaxed state, codes must be run for at least 200 binary orbits, corresponding to about a viscous time for our parameters, 0.2(a 2Ω B /ν) binary orbits, where ν is the kinematic viscosity. The largest discrepancies between codes resulted from the dimensionality of the setup (3D vs. 2D disks). We find good agreement in the total torque on the binary between codes, although the partition of this torque between the gravitational torque, orbital accretion torque, and spin accretion torque depends sensitively on the sink prescriptions employed. In agreement with previous studies, we find a modest difference in torques and accretion variability between 2D and 3D disk models. We find cavity precession rates to be appreciably faster in 3D than in 2D.

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Electromagnetic signatures from accreting massive black hole binaries in time domain photometric surveys

Cocchiararo,

Franchini,

Lupi

et al. 2024

A&A

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We study spectral and time variability of accreting massive black hole binaries (MBHBs) at milli-parsec separations surrounded by a geometrically thin circumbinary disc. To this end, we present the first computation of the expected spectral energy distribution (SED) and light curves (LCs) from 3D hyper-Lagrangian resolution hydrodynamic simulations of these systems. We modelled binaries with a total mass of $10^6$ M$_ eccentricities of $e=0,\, 0.9$, and a mass ratio of $q=0.1,\, 1$. The circumbinary disc has an initial aspect ratio of 0.1, features an adiabatic equation of state, and evolves under the effect of viscous heating, black-body cooling, and self gravity. To construct the SED, we considered black-body emission from each element of the disc and we added a posteriori an X-ray corona with a luminosity proportional to that of the mini-discs that form around each individual black hole. We find significant variability of the SED, especially at high energies, which translates into LCs displaying distinctive modulations of a factor of $ 2$ in the optical and of $ 10$ in UV and X-rays. We analysed in detail the flux variability in the optical band that will be probed by the Vera Rubin Observatory (VRO). We find clear modulations on the orbital period and half of the orbital period in all systems. Only in equal-mass binaries, we find an additional, longer-timescale modulation, associated with an over-density forming at the inner edge of the circumbinary disc (commonly referred to as a lump). When considering the VRO flux limit and nominal survey duration, we find that equal-mass, circular binaries are unlikely to be identified, due to the lack of prominent peaks in their Fourier spectra. Conversely, unequal-mass and/or eccentric binaries can be singled out up to $z 0.5$ (for systems with bol $ erg s$^ $) and $z 2$ (for systems with bol $ erg s$^ $). Identifying electromagnetic signatures of MBHBs at separations of $ $ pc is of paramount importance to understand the physics of the gravitational wave (GW) sources of the future Laser Interferometer Space Antenna, and to pin down the origin of the GW background (GWB) observed in pulsar timing arrays.

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Eccentric Minidisks in Accreting Binaries

Cited by 8 publications

References 78 publications

Reliable Identification of Binary Supermassive Black Holes from Rubin Observatory Time-domain Monitoring

Reliable Identification of Binary Supermassive Black Holes from Rubin Observatory Time-domain Monitoring

The Santa Barbara Binary−disk Code Comparison

Electromagnetic signatures from accreting massive black hole binaries in time domain photometric surveys

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