---
title: "Our Galaxy Might Have — Two! — Black Holes at Its Center"
description: "Double Down We already know that our Milky Way galaxy is home to Sagittarius A*, a black hole with a mass about 4 million times that of our Sun. But an international team of astrophysicists suspects that Sgr A* might have a smaller companion black hole — and they think they know how to find out […]"
date: "2019-12-13"
modified: "2019-12-13"
authors:
  - name: "Kristin Houser"
    link: "https://futurism.com/authors/kristin"
url: "https://futurism.com/the-byte/milky-way-galaxy-two-black-holes"
categories:
  - "Astrophysics"
  - "Black Holes"
  - "Science & Energy"
  - "Space"
tags:
  - "black hole"
  - "laser interferometer space antenna"
  - "Sagittarius A*"
  - "the digest"
---

# Our Galaxy Might Have — Two! — Black Holes at Its Center

![The Milky Way might be home to two black holes and not just one — and researchers have a plan for detecting Sagittarius A\*'s "hidden friend."](<https://futurism.com/wp-content/uploads/2019/12/milky-way-galaxy-two-black-holes.png>)
*\<em\>Image: NASA/Victor Tangermann\</em\>*

## Double Down

We already know our galaxy, the Milky Way, as home to Sagittarius A\*, a black hole with a mass about 4 million times that of the Sun.

But an international team of astrophysicists suspects that Sgr A\* might have a smaller companion black hole. Now, they think they've figured out how to determine if they're right.

## Hidden Friend

On Thursday, UCLA astrophysicist Smadar Naoz's had a [story](<https://theconversation.com/supermassive-black-hole-at-the-center-of-our-galaxy-may-have-a-friend-128295>) published in *Conversation* detailing [paper](<https://arxiv.org/pdf/1912.04910.pdf>) she and her colleagues shared on the pre-print server *arXiv*. Based on their observations of star S0-2, which orbits Sgr A\* every 16 years, the researchers know that the Milky Way's supermassive black hole *couldn't* have a companion with a mass greater than 100,000 times that of our Sun. But they aren't ruling out a smaller "hidden friend."

## Ancient History

Naoz believes the [Laser Interferometer Space Antenna](<https://lisa.nasa.gov/>), a mission expected to launch in the 2030s, might allow scientists to determine whether or not Sgr A\* indeed has a companion by detecting its gravitational waves.

If the Milky Way *is* home to two black holes, that would imply it once merged with another galaxy, Naoz wrote — meaning Sgr A\*'s "hidden friend" could tell us something new about our galaxy both today, and in the distant past.

**READ MORE**: [Supermassive black hole at the center of our galaxy may have a friend](<https://theconversation.com/supermassive-black-hole-at-the-center-of-our-galaxy-may-have-a-friend-128295>) \[*The Conversation*\]

**More on black holes:** *[NASA’s New Black Hole Simulation Will Completely Melt Your Brain](<https://futurism.com/the-byte/nasa-black-hole-visualization>)*

### Author social links  
[LinkedIn](<https://www.linkedin.com/in/kristinjhouser>)