Detectability of gravitational waves from primordial black holes orbiting Sgr 
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Bondani, Stefano; Haardt, Francesco; Sesana, Alberto; Barausse, Enrico; Dotti, Massimo

doi:10.1103/physrevd.106.043015

Cited by 3 publications

(2 citation statements)

References 46 publications

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“…The key test is from LISA to detect the strains and polarizations of the mHz gravitational waves from the EMRI and its orbital decays. See some detailed calculations of mHz gravitational waves from an EMRI, which can be found in Fang et al (2019), Bondani et al (2022) and Tahura et al (2022). Considering the general relativistic effects, the Schartzshild procession of the sMBH is about ∆ϕ ∼ 6πR g /R • ≈ 108 • r −1 1 per period for a circular orbit.…”

Section: Mhz Gravitational Wavesmentioning

confidence: 99%

Accretion-modified Stars in Accretion Disks of Active Galactic Nuclei: Slowly Transient Appearance

Wang

Liu

et al. 2021

ApJL

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Compact objects are expected to exist in the accretion disks of supermassive black holes (SMBHs) in active galactic nuclei (AGNs), and in the presence of such a dense environment (∼1014 cm−3), they will form a new kind of stellar population denoted as accretion-modified stars (AMSs). This hypothesis is supported by recent LIGO/Virgo detection of the mergers of very high-mass stellar binary black holes (BHs). We show that the AMSs will be trapped by the SMBH disk within a typical AGN lifetime. In the context of SMBH disks, the rates of Bondi accretion onto BHs are ∼109 L Edd/c 2, where L Edd is the Eddington luminosity and c is the speed of light. Outflows developed from the hyper-Eddington accretion strongly impact the Bondi sphere and induce episodic accretion. We show that the hyper-Eddington accretion will be halted after an accretion interval of t a ∼ 105 m 1 s, where m 1 = m •/10M ⊙ is the BH mass. The kinetic energy of the outflows accumulated during t a is equivalent to 10 supernovae driving an explosion of the Bondi sphere and developing blast waves. We demonstrate that a synchrotron flare from relativistic electrons accelerated by the blast waves peaks in the soft X-ray band (∼0.1 keV), significantly contributing to the radio, optical, UV, and soft X-ray emission of typical radio-quiet quasars. External inverse Compton scattering of the electrons peaks around 40 GeV and is detectable through Fermi-LAT. The flare, decaying with t −6/5 with a few months, will appear as a slowly varying transient. The flares, occurring at a rate of a few per year in radio-quiet quasars, provide a new mechanism for explaining AGN variability.

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Section: Mhz Gravitational Wavesmentioning

confidence: 99%

Accretion-modified Stars in Accretion Disks of Active Galactic Nuclei: Slowly Transient Appearance

Wang

Liu

et al. 2021

ApJL

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show abstract

“…The key test is from LISA to detect the strains and polarizations of the mHz GWs from the EMRI and its orbital decays. See some detailed calculations of mHz GWs from an EMRI, which can be found in Fang et al (2019), Bondani et al (2022), andTahura et al (2022). Considering the general relativistic effects, the Schartzshild procession of the sMBH is about…”

Section: Mhz Gravitational Wavesmentioning

confidence: 99%

Accretion-modified Stars in Accretion Disks of Active Galactic Nuclei: The Low-luminosity Cases and an Application to Sgr A*

Wang,

Liu,

et al. 2023

ApJL

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In this paper, we investigate the astrophysical processes of stellar-mass black holes (sMBHs) embedded in advection-dominated accretion flows (ADAFs) of supermassive black holes (SMBHs) in low-luminosity active galactic nuclei. The sMBH is undergoing Bondi accretion at a rate lower than the SMBH. Outflows from the sMBH-ADAF dynamically interact with their surroundings and form a cavity inside the SMBH-ADAF, thereby quenching the accretion onto the sMBH. Rejuvenation of the Bondi accretion is rapidly done by turbulence. These processes give rise to quasi-periodic episodes of sMBH activities and create flickerings from relativistic jets developed by the Blandford–Znajek mechanism if the sMBH is maximally rotating. Accumulating successive sMBH-outflows trigger a viscous instability of the SMBH-ADAF, leading to a flare following a series of flickerings. Recently, the similarity of near-infrared flare’s orbits has been found by GRAVITY/VLTI astrometric observations of Sgr A∗: their loci during the last 4 yr consist of a ring in agreement with the well-determined SMBH mass. We apply the present model to Sgr A*, which shows quasi-periodic flickerings. An sMBH of ∼40M ⊙ is preferred orbiting around the central SMBH of Sgr A* from fitting radio to X-ray continuum. Such an extreme mass ratio inspiraling provides an excellent laboratory for LISA/Taiji/Tianqin detection of mHz gravitational waves with strains of ∼10−17, as well as their polarization.

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Gravitational waves from an eccentric population of primordial black holes orbiting Sgr A*

Bondani,

Bonetti,

Broggi

et al. 2024

Phys. Rev. D

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Detectability of gravitational waves from primordial black holes orbiting Sgr A*

Cited by 3 publications

References 46 publications

Accretion-modified Stars in Accretion Disks of Active Galactic Nuclei: Slowly Transient Appearance

Accretion-modified Stars in Accretion Disks of Active Galactic Nuclei: Slowly Transient Appearance

Accretion-modified Stars in Accretion Disks of Active Galactic Nuclei: The Low-luminosity Cases and an Application to Sgr A*

Gravitational waves from an eccentric population of primordial black holes orbiting Sgr A*

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