Artistic concept for the James Webb Space Telescope. Credit: NASA GSFC / CIL / Adriana Manrique Gutierrez
The Webb Space Telescope team continues to work on the commissioning of scientific instruments, the final step before launching scientific operations in the summer. We recently saw the spectacular image of the black hole in the center of our Milky Way galaxy taken by the Event Horizon Telescope. One of the puzzles of modern astronomy is how every large galaxy has a huge central black hole, and how some of these black holes are surprisingly large even in the very early days of the universe. We asked Roberto Mayolino, a member of Webb’s Near Infrared Spectrometer (NIRSpec) team, to tell us how Webb will help answer some of these questions.
“One of the most exciting areas of discovery that the Web is about to discover is the search for primary black holes in the early universe. These are the seeds of the much more massive black holes that astronomers have discovered in galactic nuclei. Most (probably all) galaxies contain black holes at their centers, with masses ranging from millions to billions of times the mass of our Sun. These supermassive black holes have grown to so large both by absorbing matter around them and by merging smaller black holes.
“An intriguing recent discovery is the discovery of hypermassive black holes with masses of several billion solar masses, which already existed when the universe was only about 700 million years old, a small part of its current age of 13.8 billion years. This is a puzzling result, as in such early eras there is not enough time to grow such hyper-massive black holes, according to standard theories. Some scenarios have been suggested to resolve this conundrum.
“One possibility is that black holes, the result of the death of the first generation of stars in the early universe, have accumulated material at extremely high speeds. Another scenario is that primary, virgin gas clouds, which are not yet enriched with chemical elements heavier than helium, could collapse directly to form a black hole with a mass of several hundred thousand solar masses and subsequently accumulate matter. to develop into hypermassive. black holes observed in later epochs. Finally, the dense nuclear star clusters at the centers of small galaxies may have produced seeds of intermediate-mass black holes by stellar collisions or fusion of star-mass black holes and then become much more massive by aggregation.
This illustration shows the populations of known black holes (large black dots) and the candidate precursors of the black hole in the early universe (shady regions). Credit: Roberto Mayolino, University of Cambridge
“Webb is about to open up a whole new space for discoveries in this area. It is possible that the first black hole seeds first formed in the “baby universe” just a few million years after the Big Bang. Webb is the perfect “time machine” for learning about these primary objects. Its extreme sensitivity makes Webb capable of detecting extremely distant galaxies, and because of the time it takes for light emitted by galaxies to travel to us, we will see them as they were in the distant past.
“Webb’s NIRSpec tool is particularly suitable for identifying primary black hole seeds. My colleagues on the NIRSpec Instrument Science team and I will be looking for their signatures during the “active” phases, when they eagerly absorb matter and grow fast. In these phases, the material around them becomes extremely hot and luminous and ionizes the atoms in their environment and in their host galaxies.
NIRSpec will scatter light from these systems into spectra or “arcs”. The rainbow of active black hole seeds will be characterized by specific “fingerprints”, characteristics of highly ionized atoms. NIRSpec will also measure the speed of gas in orbit near these primary black holes. Smaller black holes will be characterized by lower orbital velocities. Seeds of black holes formed in virgin clouds will be identified by the absence of characteristics associated with any element heavier than helium.
“I look forward to using the Web’s unprecedented capabilities to search for these black hole predecessors, with the ultimate goal of understanding their nature and origins. The early universe and the realm of the seeds of black holes are completely unexplored territory that my colleagues and I are very excited to explore with the Web.
– Roberto Mayolino, Professor of Experimental Astrophysics and Director of the Cowley Institute of Cosmology, University of Cambridge
Written by:
- Jonathan Gardner, Webb’s Deputy Senior Scientist at NASA’s Goddard Space Flight Center
- Stephanie Milam, Webb’s Deputy Scientist for Planetary Science, NASA’s Goddard Space Flight Center
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