Lucy (Cheng) Nie
UCLA
This guest post was written by Lucy Cheng Nie. She is a first year student at UCLA studying business economics, but some of her happiest memories are from planetariums and observatories. Apart from staring up into the night sky, you might also find her at an ice rink in figure skates, or somewhere curled up with a good novel.
Title: The central kinematics and black hole mass of 4C+37.11
Authors: Tirth Surti, Roger W. Romani, Julia Scharwächter et. al.
First Authors’ Institutions: Stanford University, Université de Strasbourg
Status: Published in ApJ [open access]
In the depths of space, two supermassive black holes dance around each other in a cosmic pas de deux. This mesmerising waltz is happening at the heart of a galaxy known as 4C+37.11, a massive elliptical galaxy embedded in a bright X-ray halo. The story of this galactic odd couple has been unfolding through the work of astronomers, who have been piecing together clues about the nature of this system and its impact on the galaxy it calls home.
The story of 4C+37.11 begins with previous studies that identified two compact, central components within the galaxy, suggesting the presence of a gravitationally bound supermassive black hole binary (SMBHB). These studies noted the variable nature of these components, indicating that they are changing over time, which hints at interactions between the two black holes. Additionally, the galaxy’s massive size and bright X-ray halo provided further evidence of a history of major mergers, which could have brought the two black holes together.
Investigating the Stellar Dynamics
Intrigued by these findings, a team of researchers set out to investigate the motion and distribution of stars within 4C+37.11’s host galaxy. Their primary goal was to understand how the binary black hole system has influenced the galaxy’s structure through a process known as “scouring.” In this process, the powerful gravitational forces of the black holes eject stars from the galaxy’s centre, creating a large, hollow core that stands as a testament to the black holes’ profound impact on their cosmic home.
To unravel the mysteries of this galactic dance, the researchers employed a multi-faceted approach, combining high-resolution imaging and spectroscopy to gather detailed observations of the galaxy’s centre. Using data from the Gemini North telescope, they obtained a wealth of information that allowed them to measure the velocities of stars within the galaxy. This information was crucial in understanding the kinematic properties of 4C+37.11 and how they have been shaped by the presence of the SMBHB.
In addition to these observations, the researchers applied sophisticated modelling techniques to estimate the mass of the supermassive black hole binary (SMBHB) and its impact on the surrounding stellar velocities. By refining the spectroscopic data and applying spatial optimisation techniques, they were able to analyse the data using advanced fitting methods, such as neural networks. This allowed them to measure the velocity distribution of stars within the galaxy. The detailed dynamical modelling provided crucial insights into the mass and gravitational influence of the supermassive black hole binary (SMBHB) at the centre of the galaxy. By analysing the velocity distribution of stars and comparing it with theoretical models, the researchers were able to estimate the total mass of the SMBHB and understand its impact on the galaxy’s structure and dynamics.
Discovering the Massive Binary Black Hole
The researchers concluded that 4C+37.11 hosts an incredibly massive SMBHB, likely the product of historical galaxy mergers. With a combined mass of around 28 billion times that of our Sun, this binary system is one of the most massive of its kind ever discovered. The interaction between the two supermassive black holes has created a large, empty core within the galaxy, confirming the scouring effect and providing a striking example of how SMBHBs can dramatically reshape their host galaxies.
The implications of this study extend far beyond the confines of 4C+37.11. By demonstrating the profound impact that binary black hole systems can have on the structural dynamics of their host galaxies, this research contributes to our broader understanding of galaxy evolution. It is truly fascinating to consider how the dance of two supermassive black holes can lead to such significant and observable changes in the very fabric of a galaxy.
As we look to the future, the authors of the study suggest that further investigations into the galaxy’s stellar velocities could help refine the estimates of the SMBHB’s mass and provide a better understanding of how the stars move in different directions within the galaxy. The upcoming James Webb Space Telescope (JWST) mission, with its advanced infrared capabilities, holds the promise of providing even more detailed observations of the galaxy’s core. These observations could shed light on the complex processes that shape galaxies and raise questions about the prevalence and implications of SMBHB systems across the universe. The story of 4C+37.11 and its central black hole duo is a captivating chapter in the grand saga of our cosmos, reminding us of the complex and often surprising ways in which the universe evolves.
Astrobite edited by: Katherine Lee
Featured image credit: NASA/CXC/A.Hobart, Public domain, via Wikimedia Commons
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