Showing papers by "László Gondán published in 2021"
TL;DR: In this paper, the authors take into account the effects of dynamical friction, post-Newtonian corrections, and observational bias to determine the detected sources' parameter distributions from all GNs in the Universe.
Abstract: The emission of gravitational waves (GWs) during single-single close encounters in galactic nuclei (GNs) leads to the formation and rapid merger of highly eccentric stellar-mass black hole (BH) binaries. The distinct distribution of physical parameters makes it possible to statistically distinguish this source population from others. Previous studies determined the expected binary parameter distribution for this source population in single GNs. Here we take into account the effects of dynamical friction, post-Newtonian corrections, and observational bias to determine the detected sources' parameter-distributions from all GNs in the Universe. We find that the total binary mass distribution of detected mergers is strongly tilted towards higher masses. The distribution of initial peak GW frequency is remarkably high between 1-70 Hz, ~50% of GW capture sources form above 10 Hz with e >~ 0.95. The eccentricity when first entering the LIGO/Virgo/KAGRA band satisfies e_10Hz > 0.1 for over 92% of sources and e_10Hz > 0.8 for more than half of the sources. At the point when the pericenter reaches 10 GM/c^2 the eccentricity satisfies e_10M > 0.1 for over ~70% of the sources, making single-single GW capture events in GNs the most eccentric source population among the currently known stellar-mass binary BH merger channels in the Universe. We identify correlations between total mass, mass ratio, source detection distance, and eccentricities e_10Hz and e_10M. The recently measured source parameters of GW190521 lie close to the peak of the theoretical distributions and the estimated escape speed of the host environment is ~7.5x10^3 km/s - 1.2x10^4 km/s, making this source a candidate for this astrophysical merger channel.
53 citations
Posted Content•
TL;DR: In this article, the authors examined a smoking-gun signature to identify sources in GNs: the GWs scattered by the central supermassive black hole (SMBH), which produces a secondary signal, an astrophysical GW echo, which has a very similar time-frequency evolution as the primary signal but arrives after a time delay.
Abstract: Galactic nuclei (GNs) are dense stellar environments abundant in gravitational-wave (GW) sources for LIGO, VIRGO, and KAGRA. The GWs may be generated by stellar-mass black hole (BH) or neutron star mergers following gravitational bremsstrahlung, dynamical scattering encounters, Kozai-Lidov type oscillations driven by the central supermassive black hole (SMBH), or gas-assisted mergers if present. In this paper, we examine a smoking gun signature to identify sources in GNs: the GWs scattered by the central SMBH. This produces a secondary signal, an astrophysical GW echo, which has a very similar time-frequency evolution as the primary signal but arrives after a time delay. We determine the amplitude and time-delay distribution of the GW echo as a function of source distance from the SMBH. Between $10\%-90\%$ of the detectable echoes arrive within $(1-100)M_6\,\mathrm{sec}$ after the primary GW for sources between $10-10^4\,r_{\rm S}$, where $r_{\rm S}=2GM/c^2$, $M$ is the observer-frame SMBH mass, and $M_6=M/(10^6\,M_{\odot})$. The echo arrival times are systematically longer for high signal-to-noise ratio (SNR) primary GWs, where the GW echo rays are scattered at large deflection angles. In particular, $10\%-90\%$ of the distribution is shifted to $(5-1800)M_6\,\mathrm{sec}$ for sources, where the lower limit of echo detection is $0.02$ of the primary signal amplitude. We find that $5\%-30\%$ ($1\%-7\%$) of GW sources have an echo amplitude larger than $0.2-0.05$ times the amplitude of primary signal if the source distance from the SMBH is $r=50\,r_{\rm S}$ ($200\,r_{\rm S}$). Non-detections can rule out that a GW source is near an SMBH.
5 citations
TL;DR: In this paper, the upper limits on α presented in Figure 3 and Table 4 of the published article were computed incorrectly, and the corrected Figure 3 (bottom) shows the corrected upper limits for the G266.2-1.2 (Vela Jr.) wide search.
Abstract: Equation (7) of the published article (Aasi et al. 2015) is in error; it should read (Equation presented). The upper limits on o presented in the published article are unaffected by this error. Equation (8) of the published article is in error; it should read (Equation presented) The upper limits on α presented in Figure 3 and Table 4 of the published article were computed incorrectly. The revised Figure 3 (bottom) shows the corrected upper limits on α for the G266.2-1.2 (Vela Jr.) wide search. The revised Table 4 is provided here. The correct lowest upper limit on α (quoted in the Abstract of the published article) is 3 × 10-6. Figure 4 shows the incorrect and corrected upper limits on α for the G266.2-1.2 (Vela Jr.) wide search, which have been surpassed by upper limits from Abbott et al. (2019).