Supermassive black holes tend to sit, more or less stationary, at the centers of galaxies. But not all of these awesome cosmic objects stay put; some may be knocked askew, wobbling around galaxies like cosmic nomads.
We call such black holes ‘wanderers’, and they’re largely theoretical, because they are difficult (but not impossible) to observe, and therefore quantify. But a new set of simulations has allowed a team of scientists to work out how many wanderers there should be, and whereabouts – which in turn could help us identify them out there in the Universe.
This could have important implications for our understanding of how supermassive black holes – monsters millions to billions of times the mass of our Sun – form and grow, a process that is shrouded in mystery.
Cosmologists think that supermassive black holes (SMBHs) reside at the nuclei of all – or at least most – galaxies in the Universe. These objects’ masses are usually roughly proportional to the mass of the central galactic bulge around them, which suggests that the evolution of the black hole and its galaxy are somehow linked.
But the formation pathways of supermassive black holes are unclear. We know that stellar-mass black holes form from the core collapse of massive stars, but that mechanism doesn’t work for black holes over about 55 times the mass of the Sun.
Astronomers think that SMBHs grow via the accretion of stars and gas and dust, and mergers with other black holes (very chunky ones at nuclei of other galaxies, when those galaxies collide).
But cosmological timescales are very different from our human timescales, and the process of two galaxies colliding can take a very long time. This makes the potential window for the merger to be disrupted quite large, and the process could be delayed or even prevented entirely, resulting in these black hole ‘wanderers’.
A team of astronomers led by Angelo Ricarte of the Harvard & Smithsonian Center for Astrophysics has used the Romulus cosmological simulations to estimate how frequently this ought to have occurred in the past, and how many black holes would still be wandering today.
These simulations self-consistently track the orbital evolution of pairs of supermassive black holes, which means they are able to predict which black holes are likely to make it to the center of their new galactic home, and how long this process should take – as well as how many never get there.
“Romulus predicts that many supermassive black hole binaries form after several billions of years of orbital evolution, while some SMBHs will never make it to the center,” the researchers wrote in their paper.
“As a result, Milky Way-mass galaxies in Romulus are found to host an average of 12 supermassive black holes, which typically wander the halo far from the galactic center.”
In the early Universe, before about 2 billion years after the Big Bang, the team found, wanderers both outnumber and outshine the supermassive black holes in galactic nuclei. This means they would produce most of the light we would expect to see shining from the material around active SMBHs, glowing brightly as it orbits and accretes onto the black hole.
They remain close to their seed mass – that is, the mass at which they formed – and probably originate in smaller satellite galaxies that orbit larger ones.
And some wanderers should still be around today, according to the simulations. In the local Universe, there should actually be quite a few hanging around.
“We find that the number of wandering black holes scales roughly linearly with the halo mass, such that we expect thousands of wandering black holes in galaxy cluster halos,” the researchers wrote.
“Locally, these wanderers account for around 10 percent of the local black hole mass budget once seed masses are accounted for.”
These black holes may not necessarily be active, and therefore would be very difficult to spot. In an upcoming paper, the team will be exploring in detail the possible ways we could observe these lost wanderers.
The research has been published in the Monthly Notices of the Royal Astronomical Society.
A Mystery Rocket Left A Crater On The Moon – Forbes
While we think of the moon as a static place, sometimes an event happens that reminds us that things can change quickly.
On March 4, a human-made object (a rocket stage) slammed into the moon and left behind a double crater, as seen by NASA’s Lunar Reconnaissance Orbiter (LRO) mission.
Officials announced June 23 that they spotted a double crater associated with the event. But what’s really interesting is there’s no consensus about what kind of rocket caused it.
China has denied claims that the rocket was part of a Long March 3 rocket that launched the country’s Chang’e-5 T1 mission in October 2014, although the orbit appeared to match. Previous speculation suggested it might be from a SpaceX rocket launching the DISCOVR mission, but newer analysis has mostly discredited that.
On a broader scale, the value of LRO observations like this is showing how the moon can change even over a small span of time. The spacecraft has been in orbit there since 2009 and has spotted numerous new craters since its arrival.
It’s also a great spacecraft scout, having hunted down the Apollo landing sites from orbit and also having tracked down a few craters from other missions that slammed into the moon since the dawn of space exploration.
It may be that humans return to the moon for a closer-up look in the coming decade, as NASA is developing an Artemis program to send people to the surface no earlier than 2025.
LRO will also be a valuable scout for that set of missions, as the spacecraft’s maps will be used to develop plans for lunar bases or to help scout safe landing sites for astronauts.
A new planet hunter awakens: NIRPS instrument sees first light – News | Institute for Research on Exoplanets
The Near InfraRed Planet Searcher (NIRPS) instrument, developed in part at the Université de Montréal and the Université Laval, has successfully performed its first observations. Mounted on ESO’s 3.6-m telescope at the La Silla Observatory in Chile, NIRPS’s mission is to search for new exoplanets around stars in the solar neighbourhood.
“NIRPS has been a long time in the making, and I’m thrilled with how this mission has come together!” says René Doyon, Director of the Observatoire du Mont-Mégantic and Institute for Research on Exoplanets, Université de Montréal, and co-Principal Investigator of NIRPS. “This incredible infrared instrument will help us find the closest habitable worlds to our own Solar System.”
The instrument will focus its search on rocky worlds, which are key targets for understanding how planets form and evolve, and are the most likely planets where life may develop. NIRPS will search for these rocky exoplanets around small, cool red dwarf stars — the most common type of stars in our Milky Way galaxy, which have masses from about two to ten times smaller than our Sun.
NIRPS will search for exoplanets using the radial velocity method. As a planet orbits a star, its gravitational attraction causes the star to “wobble” slightly, causing its light to be redshifted or blueshifted as it moves away from or towards Earth. By measuring the subtle changes in the light from the star, NIRPS will help astronomers measure the mass of the planet as well as other properties.
NIRPS will search for these spectral wobbles using near-infrared light as this is the main range of wavelengths emitted by such small, cool stars. It joins the High Accuracy Radial velocity Planet Searcher (HARPS) in the hunt for new rocky worlds. HARPS, which has been installed on ESO’s 3.6-m telescope at the La Silla Observatory in Chile since 2003, also uses the radial velocity method, but operates using visible light. Using both instruments simultaneously will provide a more comprehensive analysis of these rocky worlds.
Another key difference between the two instruments is that NIRPS will rely on a powerful adaptive optics system. Adaptive optics is a technique that corrects for the effects of atmospheric turbulence, which cause stars to twinkle. By using it, NIRPS will more than double its efficiency in both finding and studying exoplanets.
“NIRPS joins a very small number of high-performance near-infrared spectrographs and is expected to be a key player for observations in synergy with space missions like the James Webb Space Telescope and ground-based observatories,” adds François Bouchy, from the University of Geneva, Switzerland, and co-Principal Investigator of NIRPS.
Discoveries made with NIRPS and HARPS will be followed up by some of the most powerful observatories in the world, such as ESO’s Very Large Telescope and the upcoming Extremely Large Telescope in Chile (for which similar instruments are in development). By working together with both space- and ground-based observatories, NIRPS will be able to gather clues on an exoplanet’s composition and even look for signs of life in its atmosphere.
NIRPS was built by an international collaboration led by the Observatoire du Mont-Mégantic and the Institute for Research on Exoplanets team at the Université de Montréal in Canada and the Observatoire Astronomique de l’Université de Genève in Switzerland. Much of the mechanical and optical assembly and testing of the instrument was performed over the last few years at Université Laval’s Centre for Optics, Photonics and Lasers (COPL) laboratories by Prof. Simon Thibault and his team. The National Research Council of Canada’s Herzberg Astronomy and Astrophysics Research Centre contributed to the conception and construction of the spectrograph.
“After two years of integrating and testing the instrument in the lab, it is amazing for the optical engineering team to see NIRPS on the sky.” mentions Prof. Simon Thibault who is affiliated with the COPL and iREx and who overviewed optical integration and test phases at Université Laval.
Many Canadian members of the NIRPS have been working on site at La Silla for the instrument’s commissioning period and will continue to do so over the next several months to ensure the NIRPS’s scientific operations. The NIRPS science team, which includes several Canadian astronomers, is guaranteed 720 nights on the instrument during its first 5 years of operations due to their important contribution to the project. While the whole team was excited for NIRPS’s first light, it is safe to say that the best is yet to come!
The institutes involved in the NIRPS consortium are the Université de Montréal, Canada; the Université de Genève, Observatoire Astronomique, Switzerland; the Instituto de Astrofísica e Ciências do Espaço, Porto, Portugal; the Instituto de Astrofísica de Canarias, Spain; the Université de Grenoble, France; and the Universidade Federal do Rio Grande do Norte, Brazil.
The Canadian NIRPS team, led by Université de Montréal/The Institute for Research on Exoplanets/Observatoire du Mont-Mégantic and including Université Laval, the National Research Council of Canada’s Herzberg Astronomy and Astrophysics Research Centre, and the Royal Military College, was awarded funding by the Canadian Fund for Innovation to build the NIRPS instrument.
Professor, NIRPS co-Principal Investigator
Institute for Research on Exoplanets and Observatoire du Mont-Mégantic — Université de Montréal
Tel: +1 514 343 6111 x3204
Professor, NIRPS optical engineering team
Centre for Optics, Photonics and Lasers — Université Laval
Tel: +1 418 656 2131 x 412766
Research Associate, NIRPS optical engineering team
Centre for Optics, Photonics and Lasers — Université Laval
Tel: +1 418 656 2131 x 404646
Rocket Lab’s CAPSTONE mission to the moon is key to establishing a lunar space station – TechCrunch
It may look like Rocket Lab is just launching a microwave-sized hunk of metal to the moon — but it’s crucial for our future in space
“Going to the moon is no joke.” So said Rocket Lab CEO Peter Beck, just days before the planned launch of CAPSTONE, a watershed mission for both NASA and the private space industry.
The mission is important, though you might not assume so based on the stats of the CAPSTONE CubeSat on its own: It’s about the size of a microwave oven and weighs in at just 55 pounds. But the end goal of the spacecraft’s roughly six-month stint in lunar orbit is to chart a favorable trajectory for a crewed station that will orbit the moon. Once established, that platform, dubbed Gateway, could unlock a whole new chapter in human space exploration.
Consider CAPSTONE (which stands for Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment) the first in-space step in NASA’s Artemis program, an ambitious plan to return humans to the moon by the middle of this decade. The Gateway platform could be used as a way station for lunar landers, a resupply junction for astronauts exploring the moon — or even a transfer point for missions to Mars and beyond.
The mission isn’t just a big deal for the Artemis program and public space exploration: Notably, it’s the result of a patchwork of collaboration between private industry and the space agency. The list of partners on NASA’s website for the mission includes:
And, of course, Rocket Lab for the launch services.
CAPSTONE is launching aboard a Rocket Lab Electron rocket from the company’s site on New Zealand’s remote Māhia Peninsula. “This is the highest mass and the highest performance Electron has ever had to fly by quite some margin,” Beck said. “The vehicle is absolutely stretched to its limits with respect to performance.”
In addition to actually launching the mission, Rocket Lab developed a special variant of its Photon spacecraft for this endeavor, which it’s calling the Lunar Photon. That spacecraft will conduct a series of orbits over a period of around six to eight days, increasing the velocity and apogee of the orbit over time. Then, Photon will perform the final burn, called the trans-lunar injection, which will set it on its course to the moon. Around 20 minutes after the injection, Photon and CAPSTONE will separate and the CubeSat alone will conduct the remaining maneuvers to reach its target orbit around the moon.
“The moon is a long way away,” Beck said, referring to the complexities of Photon’s maneuvers. “You’re traveling at huge velocities. So it only takes a smallest fraction of an angle error or a velocity error, and you just shoot way past where you need to be.”
“It’s like firing a bullet millions of kilometers, and it’s got to be exactly in the right place.”
An unusual orbit
The exact orbit that CAPSTONE will be exploring is called a near-rectilinear halo orbit (NRHO). That orbit, in the shape of a necklace, will bring CAPSTONE as close as 1,000 miles to the moon’s surface and as far away as 40,000 miles. Although the shape is odd, it’s a very stable orbit, which means greater efficiency and less use of propellant. NRHO was up against competing orbits, including low lunar orbit and distant retrograde orbit, as the ideal trajectory for Gateway; but as NASA explains, NRHO is a “best of both worlds” option that’ll provide astronauts with easy access to the lunar surface, a continuous line of sight to (and communication with) Earth and access to deep space.
But testing the NRHO orbit is not the only point of the mission. The CubeSat will also help NASA understand navigation, or how to generate an accurate estimation of Gateway’s trajectory, and station-keeping.
“Because the NRHO is marginally stable, Gateway and CAPSTONE will both require a gentle ‘nudge’ about once a week to stay in orbit,” Ethan Kayser, CAPSTONE mission design lead at Advanced Space, explained in a Reddit post. “CAPSTONE will be using the same strategy to design and execute these stationkeeping maneuvers, which occur once each revolution.” The eight propulsion thrusters built by Stella Exploration will be key to conducting these maneuvers.
CAPSTONE will arrive at its lunar orbit on November 13. After a roughly six-month orbital mission, NASA plans to crash the spacecraft into the moon at the end of its life. The launch is set to take place during an instantaneous launch window at 5:55 AM EDT on Tuesday, June 28, so be sure to follow TechCrunch for live coverage and reporting on the outocome of the mission launch.
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