Measuring a Black Hole 660M times as massive as our sun

This is NGC 1332, a galaxy with a black hole at its center whose mass has been measured at high precision by ALMA. Credit: Carnegie-Irvine Galaxy Survey

Findings could help shed light on how galaxies and their supermassive black holes form. It’s about 660 million times as massive as our sun, and a cloud of gas circles it at about 1.1 million mph. This supermassive black hole sits at the center of a galaxy NGC 1332, 73 million light years from Earth. And an international team of scientists that includes Rutgers associate professor Andrew J. Baker has measured its mass with unprecedented accuracy with Atacama Large Millimeter/submillimeter Array (ALMA).

A black hole can form after matter, often from an exploding star, condenses via gravity. Supermassive black holes at the centers of massive galaxies grow by swallowing gas, stars and other black holes. Stars can come close to a black hole, but as long as they’re in stable orbits and moving fast enough, they won’t enter the black hole.

Scientists think every massive galaxy, like the Milky Way, has a massive black hole at its center, Baker said. “The ubiquity of black holes is one indicator of the profound influence that they have on the formation of the galaxies in which they live,” he said. The ratio of a black hole’s mass to galaxy’s mass is important in understanding their makeup.

Research suggests the growth of galaxies and the growth of their black holes are coordinated. And if we want to understand how galaxies form and evolve, we need to understand supermassive black holes. Part of understanding supermassive black holes is measuring their exact masses. That lets scientists determine if a black hole is growing faster or slower than its galaxy. If black hole mass measurements are inaccurate, scientists can’t draw any definitive conclusions.

To measure NGC 1332’s central black hole, scientists tapped ALMA’s high-resolution observations of CO emissions from a giant disc of cold gas orbiting the hole. They also measured the speed of the gas. “This has been a very active area of research for the last 20 years, trying to characterize the masses of black holes at the centers of galaxies,” said Baker, who began studying black holes as a graduate student. “This is a case where new instrumentation has allowed us to make an important new advance in terms of what we can say scientifically.” http://news.rutgers.edu/news/measuring-black-hole-660-million-times-massive-our-sun/20160429.Vyn-IoQrK70