---
title: "Astronomers for the first time limit the masses of binary supermassive black holes in the cosmic dawn era"
description: "Scientists from Beijing Normal University, using 18 years of Parkes Pulsar Timing Array observations, have for the first time set gravitational-wave limits on the masses of binary supermassive black holes in the cosmic dawn era, excluding systems with masses of 10 billion solar masses or more."
date: 2026-11-10T18:52:03.662Z
lang: en
url: https://xab.info/en/posts/mass-limit-binary-black-holes-cosmic-dawn
tags: [black-holes, gravitational-waves, pulsar-timing-array, early-universe, astrophysics, james-webb, cosmology]
author: "Alexander Buran"
publisher: "XAB.info"
---

# Astronomers for the first time limit the masses of binary supermassive black holes in the cosmic dawn era

![An artistic depiction of binary supermassive black holes emitting gravitational waves in deep space](https://xab.info/media/2026/11/10/predel-massy-dvojnykh-chernykh-dyr-kosmicheskoe-rassvet/predel-massy-dvojnykh-chernykh-dyr-kosmicheskoe-rassvet-1.webp)

## Key Points

- First direct gravitational-wave constraints on the masses of binary supermassive black holes in the cosmic dawn era obtained
- Used 18 years of data from the Australian Parkes Pulsar Timing Array project
- Key innovation is the inclusion of cosmological redshift, extending sensitivity to objects with redshifts up to 20
- Existence of binary systems with masses of 10 billion solar masses or more excluded in quasar J0100+2802 and galaxy JADES-GS-z14-0
- Future accuracy improvements linked to data integration and observations from the Square Kilometre Array

An international scientific team led by researchers from Beijing Normal University has announced the first direct gravitational-wave constraints on the masses of binary supermassive black holes that existed during the so-called cosmic dawn. The study utilized 18 years of accumulated observations from the Australian Parkes Pulsar Timing Array project, which allowed researchers to exclude the presence of binary black hole systems with a combined mass on the order of 10 billion solar masses in two distant systems. According to the authors, these are the first such limits for objects in such an early cosmological epoch, when the age of the Universe was only hundreds of millions of years.

### How pulsars serve as cosmic clocks

The Parkes Pulsar Timing Array is a network of dozens of millisecond pulsars—rapidly rotating neutron stars that emit strictly periodic radio pulses. Due to the exceptional stability of their rotation, pulsars function as natural chronometers: a passing nanohertz gravitational wave from an orbiting binary supermassive black hole pair introduces characteristic deviations in the arrival time of pulses. A key condition for detection is that such deviations must appear simultaneously in the observations of several pulsars, which allows the signal to be separated from local noise. This method has been the primary tool for searching for gravitational waves with orbital periods of several years for the past several years.

### Redshift correction changes the picture

The central methodological innovation of the study was the inclusion of cosmological redshift in the calculation of the pulsar method's sensitivity. Previous approaches hardly accounted for the stretching of gravitational waves due to the expansion of the Universe. The authors demonstrated that a distant binary system might appear brighter to an Earth-based observer than predicted by a simple model of signal attenuation with distance: due to redshift, the wave is received at a lower frequency than that at which it was emitted, meaning that at the moment of emission, the black holes were closer to each other, moved faster, and generated a more intense signal. At a sufficiently high redshift, this amplification partially compensates for the attenuation caused by the enormous distance. As a result, the researchers extended the sensitivity estimate of the pulsar method to objects with a redshift up to 20, which corresponds to the era when the Universe was less than a billion years old.

### Two systems at the edge of the observable Universe

To verify the new approach, the authors selected two systems. The first is the bright quasar J0100+2802 at a redshift of 6.327, whose radiation was emitted when the Universe was no more than 900 million years old. The second is the galaxy JADES-GS-z14-0, discovered by the James Webb Space Telescope at a redshift of 14.32, that is, less than 300 million years after the Big Bang. For both systems, it was possible to set an upper limit on the value characterizing the combined mass of the two black holes and determining the parameters of the expected gravitational signal. The obtained data exclude the existence of systems with a mass on the order of 10 billion solar masses and above, although current sensitivity is not yet sufficient to definitively determine whether these objects themselves are binaries.

### Significance for cosmology and prospects

The result opens a fundamentally new channel for studying how supermassive black holes managed to increase their mass to billions of solar masses in the earliest eras of the Universe's existence—a question that remains one of the central mysteries of modern cosmology. The authors emphasize that as data from the Parkes Pulsar Timing Array are combined with results from other pulsar arrays, and in the future with observations from the Square Kilometre Array radiotelescope, the constraints on the masses of binary systems will become significantly more accurate. This will bring astrophysicists closer to directly testing competing scenarios for the growth of early black holes, including scenarios in which they formed and increased in mass primarily through sequential mergers.

## Fact-Check & Sources

- [Пульсары позволили установить предел массы двойных чёрных дыр в ранней Вселленой](https://www.ixbt.com/news/2026/11/10/pulsary-pozvolili-ustanovit-predel-massy-dvoinyx-cernyx-dyr-v-rannei-vsellenoi.html) - Primary source containing the full text of the Beijing Normal University results announcement. All key figures (18 years of data, redshifts 6.327 and 14.32, 10 billion solar mass threshold, redshift up to 20) are taken from this source.

## FAQ

### What is the Parkes Pulsar Timing Array and how does it work?

It is an Australian network of dozens of millisecond pulsars—rapidly rotating neutron stars that emit regular radio pulses. A passing gravitational wave from a binary black hole introduces characteristic deviations in pulse arrival times, which are simultaneously recorded across several pulsars, allowing for the detection of nanohertz gravitational waves.

### What is the main methodological innovation of the study?

The authors included cosmological redshift in the calculation of the pulsar method's sensitivity for the first time. They found that at high redshifts, gravitational waves are received at a lower frequency, which is equivalent to the black holes being closer together and moving faster at the time of emission. This amplification partially compensates for distance-related signal attenuation, extending sensitivity to objects with redshifts up to 20.

### Which systems were investigated?

Two systems: the quasar J0100+2802 at a redshift of 6.327 (radiation emitted when the Universe was no more than 900 million years old) and the galaxy JADES-GS-z14-0, discovered by the James Webb Telescope, at a redshift of 14.32 (less than 300 million years after the Big Bang).

### What was established regarding black hole masses?

An upper limit was established for both systems: the presence of binary black holes with a combined mass on the order of 10 billion solar masses or more was excluded. However, current sensitivity is not sufficient to definitively determine if these objects are indeed binaries.

### What are the prospects for this research direction?

The authors indicate that combining Parkes Pulsar Timing Array data with other pulsar arrays and future observations from the Square Kilometre Array will significantly increase the accuracy of these constraints, moving closer to testing scenarios of early supermassive black hole growth, including sequential mergers.