1 research outputs found
Signatures of Massive Black Hole Merger Host Galaxies from Cosmological Simulations I: Unique Galaxy Morphologies in Imaging
Low-frequency gravitational wave experiments such as the Laser Interferometer
Space Antenna and pulsar timing arrays are expected to detect individual
massive black hole (MBH) binaries and mergers. However, secure methods of
identifying the exact host galaxy of each MBH merger amongst the large number
of galaxies in the gravitational wave localization region are currently
lacking. We investigate the distinct morphological signatures of MBH merger
host galaxies, using the Romulus25 cosmological simulation. We produce mock
telescope images of 201 simulated galaxies in Romulus25 hosting recent MBH
mergers, through stellar population synthesis and dust radiative transfer.
Based on comparisons to mass- and redshift-matched control samples, we show
that combining multiple morphological statistics via a linear discriminant
analysis enables identification of the host galaxies of MBH mergers, with
accuracies that increase with chirp mass and mass ratio. For mergers with high
chirp masses (>10^8.2 Msun) and high mass ratios (>0.5), the accuracy of this
approach reaches >80%, and does not decline for at least >1 Gyr after numerical
merger. We argue that these trends arise because the most distinctive
morphological characteristics of MBH merger and binary host galaxies are
prominent classical bulges, rather than relatively short-lived morphological
disturbances from their preceding galaxy mergers. Since these bulges are formed
though major mergers of massive galaxies, they lead to (and become permanent
signposts for) MBH binaries and mergers that have high chirp masses and mass
ratios. Our results suggest that galaxy morphology can aid in identifying the
host galaxies of future MBH binaries and mergers.Comment: 19 pages, 10 figures. Submitted to Ap