Black hole aggression disc and torus. Credit: NASA / JPL-Caltech
The matter revolves around supermassive black holes to fund “echo” light in nearby dust clouds. These travel signs can serve as a new cosmic yardstick.
When you look up at the night sky, how do you know if the stars of light you see are bright and distant, or relatively dull and close? One way to find out is to compare how light a light object actually produces with how bright it looks. The difference between its true brightness and its apparent brightness displays the distance of the object object from the observer.
Measuring the luminosity of celestial objects is a challenge, especially with black holes that do not emit light. But the supermassive black holes in the center of most galaxies break up: they often pull a lot of objects around them, creating hot disks that spread brightly. Measuring the brightness of a bright disk will allow astronomers to measure distances Black hole And those who live in the galaxy. Measuring distances will help scientists create a better, three-dimensional map of the universe, as well as provide information on how and when objects formed.
This animation shows events that support an astrophysics technique called “echo mapping”, also called reverberation mapping. In the center is a supermassive black hole surrounded by a disk of material called an action disk. As the disk becomes brighter, it sometimes emits even short flares of visible light. The blue arrow shows light from this flash, moving away from the black hole, both towards the observer on Earth and towards the huge, sweet-shaped formation made of dust (called the torus). Light is absorbed, which heats the dust and releases infrared light. Brightening this dust is a direct response to a change in the disk – or, to someone calling it an “echo”. The red arrow shows this light away from the galaxy, in the same direction as the initial flash of visible light. Thus an observer will see the visible light first, and (with the right instrument) see the infrared light later. Deposit: NASA/JPL-Caltech
In a new study, astronomers used a technique some have dubbed “echo mapping” to measure the brightness of black hole disks in more than 500 galaxies. Published in Astrophysical Journal In September 2020, it supports the idea that this approach could be used to measure the distance between the Earth and these distant galaxies.
The process of echo mapping, also called reverberation mapping, begins when the hot disc Plasma (Atoms that have lost their electrons) become brighter near black holes, sometimes emitting even shorter flares of visible light (i.e. wavelengths that can be seen by the human eye). It travels away from the light disk and eventually enters the common feature of most supermassive black hole systems: a massive cloud of dust in the shape of a candy (also known as a torus). The disc and the torus together form a kind of bulge, the attraction disc wraps tightly around the black hole, followed by continuous rings of slightly cold plasma and gas, and finally the dust torus, forming the widest and outermost ring. Bullsey. When the flash of light from the actuation disc reaches the inner wall of the dusty torus, the light is absorbed, which heats the dust and releases infrared light. This brightening of the torus is a direct response or, as one might say, an “echo” of changes in the disc.
The distance from the impact disc inside the dust torus can be huge – billions or trillions of miles. Even light, traveling 186,000 miles (300,000 kilometers) per second, can take months or years to cross. If astronomers can observe both the initial flame of visible light in the attraction disk and the subsequent infrared brightening in the torus, they can also measure the time it takes for light to travel between those two structures. Because light travels at a standard speed, this information also gives astronomers the distance between a disk and a torus.
The progress of the events used in echo mapping, from the flash of light from the action disc to the echoes of the light away from the dust. Credit: NASA / JPL-Caltech
Scientists can then use distance measurements to calculate the brightness of a disk, and in theory, its distance from the Earth. Here’s how: The temperature of a piece of disk near a black hole can reach thousands of degrees – so high that even atoms burst and dust particles can’t form. The heat from the disc also heats the area around it, like a bonfire on a cold night. Traveling away from the black hole, the temperature gradually decreases.
Astronomers know that dust is formed when the temperature rises to about 2,200 degrees Fahrenheit (1,200) Celsius); The larger the bonfire (or the more the disc spreads), the more dust is formed away from it. Measuring the distance between the actuation disc and the torus shows the disc’s .rja output, which is directly proportional to its luminosity.
Because light can take months or years to pass through the space between a disk and a torus, astronomers need data that spans decades. The new study relies on nearly two decades of visible-light observations of black hole attraction disks, captured by several ground-based telescopes. Infrared light emitted by dust was discovered by NASA near Earth Sect Ject Budget Wide Field Infrared Survey Explorer (NEOWISE) named WISE. The spacecraft surveys the entire sky once every six months, providing astronomers with frequent opportunities to observe galaxies and find signs of light. 14 surveys of the sky were used by WISE / NEOWISE collected between 2010 and 2019. In some galaxies, light aggregation took more than 10 years to pass the distance between the disk and the dust, making them the longest resonance ever measured outside. This Milk Ganga Galaxy.
Galaxies far, far away
The idea of using echo mapping to measure the distances of galaxies away from Earth is not new, but studies have made significant progress to demonstrate its potential. One of the largest surveys of its kind, the study confirms that all galaxies play the same echo mapping, regardless of variables such as the size of black holes, which can change significantly throughout the universe. But technically not ready for prime time.
Due to multiple factors, the authors lack accuracy in measuring the distance. Most notably, the authors said, they needed to understand more about the formation of the inner regions of the dust donuts that surround black holes. That structure can affect such objects because when light reaches it, a certain wavelength of infrared light emits dust.
WISE data does not extend the range of the entire infrared wavelength, and a wide dataset can improve distance measurements. NASA’s Nancy Grace Roman Space Telescope, which will be launched in the mid-2020s, will provide targeted observations in a variety of infrared wavelength ranges. The agency’s upcoming SPARX mission (meaning Spectro-Photometer for History for the History. Historical, Epoch Refunionation and Ice Explorer) will survey the entire sky at multiple infrared wavelengths and could also help improve technology.
“The beauty of echo mapping technology is that this supermassive black hole doesn’t go away anytime soon,” said Qian Young, a researcher at the University of Illinois at Urbana-Champion and lead author of the study. Black hole disks can experience active glitter for thousands or millions of years. “So we can measure the dust echoes again for the same system to improve the distance measurement.”
Lumonosity-based distance measurements can be made with objects already known as “standard candles”, which have a known luminosity. An example is the type of explosive constellation called type 1a supernovas, which played a crucial role in the discovery of the dark energy raja (the name given to the mysterious driving force behind the dynamic expansion of the universe). Type 1 supernovas have the same luminosity, so astronomers need to measure their apparent brightness to calculate their distance from Earth.
Along with other standard candles, astronomers can measure the properties of the object to reduce its specific luminosity. The same is the case with echo mapping, where each action disc is unique but the technique of measuring luminosity is the same. There are advantages for astronomers to be able to use multiple standard candles, such as being able to compare distance measurements to confirm Accuracy, And every standard candle has strengths and weaknesses.
“Measuring universe distances is a fundamental challenge in astronomy, so the prospect of taking an extra trick in one’s sleeve is very exciting,” said Yu Shen, a researcher and co-author of the paper at the University of Illinois at Urban-No-Champion. .
References: Qian Yang, Yu Shen, Xin Liu, Michelle Aguena, James Anees, Santiago Avila, Manda Banerjee, Emmanuel Bertin, David Brooks, David Burke, ure Ralio by “ical Practical and Mid-Infrared Imagery in Imaging , Matius Caresco Kind, Luiz da Costa, Juan de Vicente, Shantanu Desai, h. Thomas Dahl, Peter Doyle, Brenna Fluger Ger, Pablo Fosalba, Josh Freeman, Juan Garcia-Belido, David Gerdes, Robert Grund Gshevend, Gaston Gutierrez, Samuel Hinton, Devon L. Hollywood, Klaus Honschad, Nicole Kuropatkin, Marcio Maia, Marissa March, Jennifer Marshall, Paul Martini, Peter Melchier, Felipe Menanteu, Ramon Mikel, Francisco Paz-Chancano, Mandre Schnein, Mandre Romero, Yuz Sevilla, Matthew Smith, Eric Suchyata, Gregory Tarley, Thames Norbert Varga and Reese Wilkinson, 1 September 2020, Astrophysical Journal.
DOI: 10.3847 / 1538-4357 / ABA 59B
Launched in 2009, the WISE spacecraft was put into hibernation in 2011 after completing its primary mission. In September 2013, NASA reactivated the spacecraft with the primary goal of scanning for near-Earth objects or NEOs, and the mission and spacecraft were renamed NEIVS. Operated and operated WISE for NASA’s Jet Propulsion Laboratory, NASA’s Science Mission Directorate in Southern California. The mission was competitively selected under NASA’s Explorer program, run by the agency’s Goddard Space Flight Center in Greenbelt, Maryland. NEOWISE is a project of JPL, a division of Caltech, and the University of Arizona, supported by NASA’s Planetary Defense Coordination Office.
