The world of black holes has long been divided into three categories: stellar-mass black holes (about five to 50 times the mass of the sun), supermassive black holes (millions to billions of times the mass of the sun), and intermediate-mass black holes with masses somewhere in between. While we know that intermediate-mass black holes should exist, little is known about their origins or characteristics – they are considered the rare “missing links” in black hole evolution.

However, four new studies have shed new light on this mystery. The research was led by a team in the lab of Assistant Professor Karan Jani, who also serves as the founding director of the Vanderbilt Lunar Labs Initiative. The work was funded by the National Science Foundation and the Vanderbilt Office of the Vice Provost for Research and Innovation.

The primary paper, “Properties of ‘Lite’ Intermediate-Mass Black Hole Candidates in LIGO-Virgo’s Third Observing Run,” was published in Astrophysical Journal Letters and led by Lunar Labs postdoctoral fellow Anjali Yelikar and astrophysics Ph.D. candidate Krystal Ruiz-Rocha. The team reanalyzed data from the Nobel-Prize winning Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors in the U.S. and the Virgo detector in Italy.

The researchers found that these waves corresponded to mergers of black holes greater than 100 to 300 times the mass of the sun, making them the heaviest gravitational-wave events recorded in astronomy. “Black holes are the ultimate cosmic fossils,” Jani said. “The masses of black holes reported in this new analysis have remained highly speculative in astronomy. This new population of black holes opens an unprecedented window into the very first stars that lit up our universe.”

Earth-based detectors like LIGO capture only a split second of the final collision of these “lightweight” intermediate-mass black holes, making it challenging to determine how the universe creates them. To tackle this, Jani’s lab turned to the upcoming European Space Agency and NASA’s Laser Interferometer Space Antenna (LISA) mission, launching in the late 2030s.

In two additional studies published in Astrophysical Journal, “A Sea of Black Holes: Characterizing the LISA Signature for Stellar-origin Black Hole Binaries,” led by Ruiz-Rocha, and “A Tale of Two Black Holes: Multiband Gravitational-wave Measurement of Recoil Kicks,” led by former summer research intern Shobhit Ranjan, the team showed LISA can track these black holes years before they merge, shedding light on their origin, evolution, and fate.

Detecting gravitational waves from black hole collisions requires extreme precision – like trying to hear a pin drop during a hurricane. In a fourth study also published in Astrophysical Journal, “No Glitch in the Matrix: Robust Reconstruction of Gravitational Wave Signals under Noise Artifacts,” the team showcased how artificial intelligence models guarantee that signals from these black holes remain uncorrupted from environmental and detector noise in the data. The paper was led by postdoctoral fellow Chayan Chatterjee and expands upon Jani’s AI for New Messengers Program, a collaboration with the Data Science Institute.

“We hope this research strengthens the case for intermediate-mass black holes as the most exciting source across the network of gravitational-wave detectors from Earth to space,” Ruiz-Rocha said. “Each new detection brings us closer to understanding the origin of these black holes and why they fall into this mysterious mass range.”

Moving forward, Yelikar said the team will explore how intermediate-mass black holes could be observed using detectors on the moon.

“Access to lower gravitational-wave frequencies from the lunar surface could allow us to identify the environments these black holes live in – something Earth-based detectors simply can’t resolve,” she said.

In addition to continuing this research, Jani will also be working with the National Academies of Sciences, Engineering, and Medicine on a NASA-sponsored study to identify high-value lunar destinations for human exploration to address decadal-level science objectives. As part of his participation in this study, Jani will be contributing to the Panel on Heliophysics, Physics, and Physical Science, to identify and articulate the science objectives related to solar physics, space weather, astronomy, and fundamental physics that would be most enabled by human explorers on the moon.

“This is an exciting moment in history – not just to study black holes, but to bring scientific frontiers together with the new opportunity of training the next generation of students whose discoveries will be shaped by, and made from, the moon,” Jani said.

The discovery of an object called ASKAP J1832-0911 has left astronomers puzzled. This mysterious entity emits pulses of radio waves and X-rays for two minutes every 44 minutes. What makes this finding even more intriguing is that it’s the first time such an object, known as a long-period transient (LPT), has been detected in X-rays.

The team behind this discovery used the ASKAP radio telescope to detect the radio signals, which they then correlated with X-ray pulses detected by NASA’s Chandra X-ray Observatory. This coincidence of observations allowed them to confirm that ASKAP J1832-0911 is indeed emitting both types of radiation.

LPTs are a relatively recent discovery, with only ten such objects found so far. Scientists still have no clear explanation for what causes these signals or why they ‘switch on’ and ‘switch off’ at such long, regular intervals. Some theories suggest that ASKAP J1832-0911 could be a magnetar or a pair of stars in a binary system with one star being a highly magnetised white dwarf.

However, even these theories don’t fully explain what’s being observed. This discovery might indicate the existence of new types of physics or models of stellar evolution. By detecting objects like ASKAP J1832-0911 using both X-rays and radio waves, scientists hope to find more examples and gain a better understanding of their nature.

The discovery of ASKAP J1832-0911 is not only significant for the scientific community but also showcases an incredible teamwork effort between researchers across the globe. The study’s findings have been published in Nature, and the object itself is located in our Milky Way galaxy about 15,000 light-years from Earth.

The discovery of ongoing surface modification on Jupiter’s moon Europa has been made possible by recent experiments conducted by Southwest Research Institute’s Dr. Ujjwal Raut and his team. Analyzing spectral data collected by the James Webb Space Telescope (JWST), they found evidence that Europa’s icy surface is constantly changing, with crystalline ice forming at different rates in various areas.

On Earth, water ice forms a crystalline structure when water molecules arrange into a hexagonal pattern during freezing. However, on Europa’s surface, exposed water ice is bombarded by charged particles from space, disrupting the crystalline structure and creating amorphous ice. The experiments conducted by Dr. Raut’s team demonstrated that this process occurs rapidly in some areas of Europa’s surface.

The combination of JWST data and laboratory results reveals a complex interplay between external processes and geologic activity affecting the surface. Researchers have long believed that Europa’s surface is covered by a thin layer of amorphous ice, protecting crystalline ice beneath. However, this new study found crystalline ice on the surface as well as at depth in certain areas, particularly in the Tara Regio region.

“We think that the surface is fairly porous and warm enough in some areas to allow the ice to recrystallize rapidly,” said Dr. Richard Cartwright, lead author of the paper and a spectroscopist at Johns Hopkins University’s Applied Physics Laboratory. “Also, in this same region, generally referred to as a chaos region, we see a lot of other unusual things, including the best evidence for sodium chloride, like table salt, probably originating from its interior ocean.”

The presence of CO2 and hydrogen peroxide on Europa’s surface is another striking feature of this study. These chemicals are believed to originate from the moon’s subsurface ocean, nearly 20 miles (30 kilometers) beneath its icy shell.

“Our data showed strong indications that what we are seeing must be sourced from the interior, perhaps from a subsurface ocean,” said Dr. Raut. “This region of fractured surface materials could point to geologic processes pushing subsurface materials up from below.”

The findings of this study have significant implications for our understanding of Europa’s surface and its potential habitability. The presence of liquid water beneath the ice, along with other substances like CO2 and hydrogen peroxide, suggests that life may be present on this moon, making it an exciting destination for future exploration.