Edu News
Search reveals eight new sources of black hole echoes
The findings will help scientists trace a black hole’s evolution as it feeds on stellar material

Written by Jennifer Chu, MIT News Office
Scattered across our Milky Way galaxy are tens of millions of black holes —immensely strong gravitational wells of spacetime, from which infalling matter, and even light, can never escape. Black holes are dark by definition, except on the rare occasions when they feed. As a black hole pulls in gas and dust from an orbiting star, it can give off spectacular bursts of X-ray light that bounce and echo off the inspiraling gas, briefly illuminating a black hole’s extreme surroundings.
Now MIT astronomers are looking for flashes and echoes from nearby black hole X-ray binaries — systems with a star orbiting, and occasionally being eaten away by, a black hole. They are analyzing the echoes from such systems to reconstruct a black hole’s immediate, extreme vicinity.
In a study appearing today in the Astrophysical Journal, the researchers report using a new automated search tool, which they’ve coined the “Reverberation Machine,” to comb through satellite data for signs of black hole echoes. In their search, they have discovered eight new echoing black hole binaries in our galaxy. Previously, only two such systems in the Milky Way were known to emit X-ray echoes.
In comparing the echoes across systems, the team has pieced together a general picture of how a black hole evolves during an outburst. Across all systems, they observed that a black hole first undergoes a “hard” state, whipping up a corona of high-energy photons along with a jet of relativistic particles that is launched away at close to the speed of light. The researchers discovered that at a certain point, the black hole gives off one final, high-energy flash, before transitioning to a “soft,” low-energy state.
This final flash may be a sign that a black hole’s corona, the region of high-energy plasma just outside a black hole’s boundary, briefly expands, ejecting a final burst of high-energy particles before disappearing entirely. These findings could help to explain how larger, supermassive black holes at the center of a galaxy can eject particles across vastly cosmic scales to shape a galaxy’s formation.
“The role of black holes in galaxy evolution is an outstanding question in modern astrophysics,” says Erin Kara, assistant professor of physics at MIT. “Interestingly, these black hole binaries appear to be ‘mini’ supermassive black holes, and so by understanding the outbursts in these small, nearby systems, we can understand how similar outbursts in supermassive black holes affect the galaxies in which they reside.”
The study’s first author is MIT graduate student Jingyi Wang; other co-authors include Matteo Lucchini and Ron Remillard at MIT, along with collaborators from Caltech and other institutions.
X-ray delays
Kara and her colleagues are using X-ray echoes to map a black hole’s vicinity, much the way that bats use sound echoes to navigate their surroundings. When a bat emits a call, the sound can bounce off an obstacle and return to the bat as an echo. The time it takes for the echo to return is relative to the distance between the bat and the obstacle, giving the animal a mental map of its surroundings.
In similar fashion, the MIT team is looking to map the immediate vicinity of a black hole using X-ray echoes. The echoes represent time delays between two types of X-ray light: light emitted directly from the corona, and light from the corona that bounces off the accretion disk of inspiraling gas and dust.
The time when a telescope receives light from the corona, compared to when it receives the X-ray echoes, gives an estimate of the distance between the corona and the accretion disk. Watching how these time delays change can reveal how a black hole’s corona and disk evolve as the black hole consumes stellar material.
Echo evolution
In their new study, the team developed search algorithm to comb through data taken by NASA’s Neutron star Interior Composition Explorer, or NICER, a high-time-resolution X-ray telescope aboard the International Space Station. The algorithm picked out 26 black hole X-ray binary systems that were previously known to emit X-ray outbursts. Of these 26, the team found that 10 systems were close and bright enough that they could discern X-ray echoes amid the outbursts. Eight of the 10 were previously not known to emit echoes.
“We see new signatures of reverberation in eight sources,” Wang says. “The black holes range in mass from five to 15 times the mass of the sun, and they’re all in binary systems with normal, low-mass, sun-like stars.”
As a side project, Kara is working with MIT education and music scholars, Kyle Keane and Ian Condry, to convert the emission from a typical X-ray echo into audible sound waves. Take a listen to the sound of a black hole echo here: https://www.youtube.com/watch?v=iIeIag2Ji8k.
The researchers then ran the algorithm on the 10 black hole binaries and divided the data into groups with similar “spectral timing features,” that is, similar delays between high-energy X-rays and reprocessed echoes. This helped to quickly track the change in X-ray echoes at every stage during a black hole’s outburst.
The team identified a common evolution across all systems. In the initial “hard” state, in which a corona and jet of high-energy particles dominates the black hole’s energy, they detected time lags that were short and fast, on the order of milliseconds. This hard state lasts for several weeks. Then, a transition occurs over several days, in which the corona and jet sputter and die out, and a soft state takes over, dominated by lower-energy X-rays from the black hole’s accretion disk.
During this hard-to-soft transition state, the team discovered that time lags grew momentarily longer in all 10 systems, implying the distance between the corona and disk also grew larger. One explanation is that the corona may briefly expand outward and upward, in a last high-energy burst before the black hole finishes the bulk of its stellar meal and goes quiet.
“We’re at the beginnings of being able to use these light echoes to reconstruct the environments closest to the black hole,” Kara says. “Now we’ve shown these echoes are commonly observed, and we’re able to probe connections between a black hole’s disk, jet, and corona in a new way.”
This research was supported, in part, by NASA.
Edu News
Innovative Ideas and Breakthroughs from NMIMS MPSTME Civil Engineering
The department has published two patents, research papers at international conferences

The Civil Engineering department of NMIMS MPSTME has been making significant strides in the field of disaster management, flood resilience, and sustainable infrastructure. The department has published two patents, research papers at international conferences, and completed several student-led projects on topics such as renewable energy, groundwater modelling, and self-healing concrete.
The first patent, ‘Automated Flood Water Regulating Multipurpose System,’ proposes a novel approach to flood resilience by constructing multipurpose wells on the banks of rivers to discharge excess water and generate hydropower. The second patent, ‘Aqua Barrier,’ is an automated mechanism that can protect any flood-prone area, regardless of its size, from any disasters caused due to water.
The student-led projects are equally impressive, with topics ranging from low-volume rural concrete roads to oscillating tidal wave energy converters. These projects showcase the department’s focus on sustainable infrastructure, renewable energy, and innovative design.
The faculty at NMIMS MPSTME Civil Engineering department, led by Head, Dr. Meenal Mategaonkar and Research coordinator, Dr. Jigisha Vashi, played a vital role in guiding and mentoring students toward research excellence. Their expertise and guidance have enabled students to participate and win awards in prestigious competitions such as the CDRI’s ‘Imagining Disaster Resilient Structures’ and The University of Queensland’s ‘Engineering Design Challenge, and AAKAR at IIT Bombay.’
The department’s success is further evidenced by the achievements of its students in national and international conferences. Students presented their research papers in Scopus Indexed papers and conferences such as the 9th Indian Young Geotechnical Engineering Conference and the Eighth Indian Young Geotechnical Conference.
Dr. Meenal Mategaonkar, Head of the Civil Engineering Department, MPSTME, NMIMS, said, “The achievements of the NMIMS MPSTME Civil Engineering department demonstrate its commitment to developing innovative solutions for complex problems in the field of civil engineering. The department’s focus on sustainable infrastructure, disaster resilience, and renewable energy is essential for addressing the challenges faced by society today. It is a testament to the hard work and dedication of both students and faculty and their commitment to excellence.”
Edu News
Embark on a Journey of Scientific Empowerment with NMIMS School of Science’s Innovative Programs!
The school is known for its strong emphasis on academic excellence, research, and innovation, and is recognized as one of the leading science schools in the country

SVKM’s NMIMS Sunandan Divatia School of Science (SDSOS) has officially announced the commencement of the admissions process for its Bachelors, Masters and Doctoral programs. The school is known for its strong emphasis on academic excellence, research, and innovation, and is recognized as one of the leading science schools in the country.
Aspiring students who are interested in pursuing a career in the field of science can now apply for various undergraduate, postgraduate, and doctoral programs offered by SDSOS. The Bachelor of Science (B.Sc.) programs are available in Applied Psychology, Biomedical Science, and Animation and VFX, while the Master of Science (M.Sc.) programs are offered in Chemistry, Biological Sciences, Applied Psychology, and Physiotherapy. The school also offers Ph.D. program in Science with various disciplines such as Chemistry, and Biological Sciences.
With a focus on creating industry-ready and research-savvy graduates, SDSOS has been at the forefront of imparting cutting-edge knowledge and practical skills through constantly evolving curriculums and state-of-the-art facilities and is situated in the heart of Mumbai.
Dr. Purvi Bhatt, I/C Dean, Sunandan Divatia School of Science, said, “The school provides a dynamic and inclusive learning environment that fosters creativity, critical thinking, and innovation. Our interdisciplinary approach to education prepares students for successful careers in science and beyond, while our emphasis on co-curricular and extracurricular activities ensures their holistic development.”
The school has a student-centric environment that supports research in niche areas of Science & Technology, state-of-the-art infrastructure, and equipment to enhance students’ hands-on skills, and a library facility that is constantly updated with the latest information. The labs at SDSOS provide modernised infrastructure and the latest equipment such as the animal tissue culture lab and the wet labs at the department of Biological Sciences offer cutting-edge technology to mould students into scientists.
School of Science offers a wide range of opportunities for students to explore their talents and interests, as well as gain valuable practical experience. The events and activities mentioned, such as Excalibur, National Science Day, Open day, Guest talks, Book Talk, Sports Day, Psych Film Fest, and club activities like photography and art, these programs provide a platform for students to demonstrate their abilities and gain insights from their peers.
Edu News
The Future of Architecture Takes Center Stage at NMIMS BSSA
Leach is a co-founder of Digital FUTURES and an academician at the Academy of Europe

NMIMS Balwant Sheth School of Architecture was excited to host Open Studio 2022-23 program by the renowned architectural theorist and digital design expert, Neil Leach, on 28th March 2023 and the title was, “Tell me that AI ain’t scary”
Leach is a co-founder of Digital FUTURES and an academician at the Academy of Europe. Leach has published over 40 books on architectural theory and digital design, including “Architecture in the Age of Artificial Intelligence: An Introduction to AI for Architects” and “The AI Design Revolution: How AI Will Transform Architecture.”
In the lecture, Leach highlighted the potential threat that artificial intelligence (AI) poses to the field of architecture. With the recent launch of GPT4 and the growing capabilities of AI, there is concern among architects that their jobs may be at risk. Leach provided an informed overview of the current state of AI and its potential impact on the architecture profession.
“We are very happy and proud to host Professor Neil Leach at the school. As a leading school of architecture, we are committed to providing our students with a comprehensive education that equips them with the skills and knowledge needed to thrive in the rapidly evolving field of design. Our Open Studio program and public lectures, and talks by experts like Neil Leach, play a critical role in this mission by enabling students to learn from distinguished scholars and practitioners and engage with cutting-edge ideas and technologies. We are excited to continue providing these opportunities and look forward to seeing the impact they will have on the future of architecture and design,” said, BSSA Dean, Dr. Kaiwan Mehta. As the field of architecture continues to evolve, it is essential to stay informed about emerging technologies and their potential impact on the profession. NMIMS BSSA School enables students to learn from experts and engage with pressing issues in architecture and design. By inviting renowned scholars and practitioners like Neil Leach to share their insights and expertise, the school provides a valuable opportunity for students to expand their knowledge and deepen their understanding of the field.
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