Future merger of the Milky Way with the Andromeda galaxy and the fate of their supermassive black holes

Abstract

Our Galaxy and the nearby Andromeda galaxy (M31) are the most massive members of the Local Group, and they seem to be a bound pair, despite the uncertainties on the relative motion of the two galaxies. A number of studies have shown that the two galaxies will likely undergo a close approach in the next 4$-$5 Gyr. We used direct $N$-body simulations to model this interaction to shed light on the future of the Milky Way - Andromeda system and for the first time explore the fate of the two supermassive black holes (SMBHs) that are located at their centers. We investigated how the uncertainties on the relative motion of the two galaxies, linked with the initial velocities and the density of the diffuse environment in which they move, affect the estimate of the time they need to merge and form ``Milkomeda''. After the galaxy merger, we follow the evolution of their two SMBHs up to their close pairing and fusion. Upon the fiducial set of parameters, we find that Milky Way and Andromeda will have their closest approach in the next 4.3 Gyr and merge over a span of 10 Gyr. Although the time of the first encounter is consistent with other predictions, we find that the merger occurs later than previously estimated. We also show that the two SMBHs will spiral in the inner region of Milkomeda and coalesce in less than 16.6 Myr after the merger of the two galaxies. Finally, we evaluate the gravitational-wave emission caused by the inspiral of the SMBHs, and we discuss the detectability of similar SMBH mergers in the nearby Universe ($z\le 2$) through next-generation gravitational-wave detectors.

arXiv comment8 Pages, 11 Figures, 1 Table. Published in A&A

References in corpus (37)

• Monitoring stellar orbits around the Massive Black Hole in the Galactic Center
• Laser Interferometer Space Antenna
• The international pulsar timing array project: using pulsars as a gravitational wave detector
• LCDM-based models for the Milky Way and M31 I: Dynamical Models
• The dynamical evolution of massive black hole binaries - I. Hardening in a fixed stellar background
• The size - virial radius relation of galaxies
• Third-Epoch Magellanic Cloud Proper Motions II: The Large Magellanic Cloud Rotation Field in Three Dimensions
• HST STIS spectroscopy of the triple nucleus of M31: two nested disks in Keplerian rotation around a Supermassive Black Hole
• The M31 Velocity Vector. II. Radial Orbit Towards the Milky Way and Implied Local Group Mass
• Science With The Australian Square Kilometre Array Pathfinder
• Equilibrium Disk-Bulge-Halo Models for the Milky Way and Andromeda Galaxies
• Hubble Space Telescope Observations of Mira Variables in the Type Ia Supernova Host NGC 1559: An Alternative Candle to Measure the Hubble Constant
• Implementing Few-Body Algorithmic Regularization with Post-Newtonian Terms
• First Determination of the Distance and Fundamental Properties of an Eclipsing Binary in The Andromeda Galaxy
• The Relationship between Galaxy and Dark Matter Halo Size from z~3 to the present
• Is the dark-matter halo spin a predictor of galaxy spin and size?
• M31 Transverse Velocity and Local Group Mass from Satellite Kinematics
• Using Tidal Tails to Probe Dark Matter Halos
• The M31 Velocity Vector. III. Future Milky Way-M31-M33 Orbital Evolution, Merging, and Fate of the Sun
• First Gaia Dynamics of the Andromeda System: DR2 Proper Motions, Orbits, and Rotation of M31 and M33
• The Collision Between The Milky Way And Andromeda
• Collisionless loss-cone refilling: there is no final parsec problem
• Long-Term Evolution of Massive Black Hole Binaries. III. Binary Evolution in Collisional Nuclei
• Swift coalescence of supermassive black holes in cosmological mergers of massive galaxies
• Relations Between the Sizes of Galaxies and their Dark Matter Halos at Redshifts $0<z<3$
• The MEGaN project II. Gravitational waves from intermediate mass- and binary black holes around a supermassive black hole
• A fully parallel, high precision, N-body code running on hybrid computing platforms
• Where Do Galaxies End?
• On the mass of the Local Group
• First Gaia Local Group Dynamics: Magellanic Clouds Proper Motion and Rotation
• Constraints on the Proper Motion of the Andromeda Galaxy Based on the Survival of Its Satellite M33
• The hangup effect in unequal mass binary black hole mergers and further studies of their gravitational radiation and remnant properties
• The Transverse velocity of the Andromeda system, derived from the M31 satellite population
• Dynamical Evolution and Merger Time-scales of LISA Massive Black Hole Binaries in Disk Galaxy Mergers
• Supermassive black holes coalescence mediated by massive perturbers: implications for gravitational waves emission and nuclear cluster formation
• The collision between the Milky Way and Andromeda and the fate of their Supermassive Black Holes
• The future Milky Way and Andromeda galaxy merger

Cited by in corpus (7)

• The proper motion of Andromeda from Gaia eDR3: confirming a nearly radial orbit
• Resequencing the Hubble sequence and the quadratic (black hole mass)-(spheroid stellar mass) relation for elliptical galaxies
• Cold and Hot gas distribution around the Milky-Way-M31 system in the HESTIA simulations
• Ultra-Low Frequency Gravitational Waves from Massive Clusters at z~1
• Interrelations between Astrochemistry and Galactic Dynamics
• Revisiting the Proper Motions of M31 and M33 Using Massive Supergiant Stars with Gaia DR3
• CosmoAmautas: Astrophysics in the high school classroom (2nd edition)