HIGH-FREQUENCY GRAVITATIONAL WAVES FROM SUPERMASSIVE BLACK HOLES: PROSPECTS FOR LIGO-VIRGO DETECTIONS

Journal Article · Fri Feb 15 04:00:00 EST 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/763/2/122· OSTI ID:22167120

Kocsis, Bence ^[1]

---

1. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

It is commonly assumed that ground-based gravitational wave (GW) instruments will not be sensitive to supermassive black holes (SMBHs) because the characteristic GW frequencies are far below the {approx}10-1000 Hz sensitivity bands of terrestrial detectors. Here, however, we explore the possibility of SMBH GWs to leak to higher frequencies. In particular, if the high-frequency spectral tail asymptotes to h-tilde (f){proportional_to}f{sup -{alpha}}, where {alpha} {<=} 2, then the spectral amplitude is a constant or increasing function of the mass M at a fixed frequency f >> c {sup 3}/GM. This will happen if the time-domain waveform or its derivative exhibits a discontinuity. Ground-based instruments could search for these universal spectral tails to detect or rule out such features irrespective of their origin. We identify the following processes which may generate high-frequency signals: (1) gravitational bremsstrahlung of ultrarelativistic objects in the vicinity of an SMBH, (2) ringdown modes excited by an external process that has a high-frequency component or terminates abruptly, and (3) gravitational lensing echoes and diffraction. We estimate the order of magnitude of the detection signal-to-noise ratio for each mechanism (1, 2, and 3) as a function of the waveform parameters. In particular for (3), SMBHs produce GW echoes of inspiraling stellar mass binaries in galactic nuclei with a delay of a few minutes to hours. The lensed primary signal and GW echo are both amplified if the binary is within a {approx}10 deg (r/100M){sup -1/2} cone behind the SMBH relative to the line of sight at a distance r from the SMBH. For the rest of the binaries near SMBHs, the amplitude of the GW echo is {approx}0.1(r/100M){sup -1} of the primary signal on average.

• OSTI ID: 22167120
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 763; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
AMPLITUDES
BLACK HOLES
BREMSSTRAHLUNG
DETECTION
DIFFRACTION
GALAXY NUCLEI
GRAVITATIONAL LENSES
GRAVITATIONAL WAVES
MASS
RELATIVISTIC RANGE
SIGNAL-TO-NOISE RATIO
SIGNALS
WAVE FORMS