From Spitzer At NASA-JPL At The California Institute of Technology Via NASA Spaceflight : “Spitzer gives scientists insights into black hole eating habits”

From Spitzer

At NASA-JPL

At

The California Institute of Technology

Via

NASA Spaceflight

The Andromeda galaxy seen in infrared by the Spitzer Space Telescope. Credit: NASA/JPL-Caltech/University of Arizona

Using data from NASA’s retired Spitzer Space Telescope, scientists have gained new insights into the eating habits of supermassive black holes at the centers of galaxies throughout the universe. These black holes often fluctuate in brightness from the massive clumps of cosmic material falling into them.

However, this is not true for the black holes located at the centers of the Milky Way and the Andromeda galaxies.

Instead, they remain fairly quiet and rarely ever vary in brightness. To find the cause of the decreased activity around the black holes, a new study used observations from Spitzer and Hubble to model the black hole and the material surrounding it at the center of the Andromeda galaxy.

In images from Spitzer, long streams of dust that span thousands of light-years in length can be seen flowing into the supermassive black hole at the center of the Andromeda galaxy — the closest major galaxy to Earth, located at about 2.5 million light-years away.

As cosmic gas and dust fall into supermassive black holes, such as the one located in Andromeda, the material heats up and begins to glow, creating light shows around the black hole that can glow brighter than entire galaxies. However, this material isn’t absorbed all at once. Instead, the material is consumed in clumps that vary in size, causing the brightness of the black hole to fluctuate.

Andromeda via Spitzer

Interestingly, the supermassive black holes located at the center of the Milky Way and Andromeda are among the quietest known black holes in the universe when it comes to consuming cosmic material (or “eating”). When light is emitted from the black holes, the light doesn’t significantly vary in brightness, which could mean the black holes are feeding off of a small and steady stream of cosmic material rather than different-sized clumps of material.

Earlier this year, a team of scientists applied the hypothesis of a black hole feeding on a small steady stream of cosmic material to the Andromeda galaxy and simulated how gas and dust around Andromeda’s black hole would behave over time. The simulation revealed that a small disk of hot gas could form near the black hole and continuously provide the black hole with a flow of cosmic material. The disk can constantly provide the material due to the disk being replenished by numerous streams of gas and dust.

However, the team also found that the streams replenishing the disk must remain within a particular size and flow rate. If they become too big or too small, the material would fall into the black hole in clumps of various sizes, leading to the black hole fluctuating in brightness — which the Milky Way and Andromeda black holes do not do.

When looking back at previous observations of Andromeda from NASA’s Hubble Space Telescope and Spitzer, the scientists found spirals of dust that fit the constraints highlighted by the simulation. Using these images, the team concluded that the spirals were indeed feeding the supermassive black hole at the center of Andromeda. This result also means that a similar process is likely taking place at the center of the Milky Way, given that the two black holes exhibit similar behaviors and characteristics.

“This is a great example of scientists reexamining archival data to reveal more about galaxy dynamics by comparing it to the latest computer simulations. We have 20-year-old data telling us things we didn’t recognize in it when we first collected it,” said co-author Almudena Prieta of the Institute of Astrophysics of the Canary Islands and the University Observatory Munich.

Andromeda via NASA/ESA Hubble

As mentioned, images from Spitzer were used to confirm the scientists’ hypothesis. Spitzer was launched in August 2003 atop a Delta II from Cape Canaveral Air Force Station and was the third telescope dedicated exclusively to observing the universe in infrared. The joint NASA, European Space Agency, and Canadian Space Agency James Webb Space Telescope is another telescope that exclusively observes in infrared. Observing in infrared has many advantages, most notably that it gives scientists the capability to see through thick layers of dust that are present in galaxies and other cosmic objects, as well as the capability to see the very early universe.

Spitzer’s observations of Andromeda were performed using different wavelengths, each revealing different features of the galaxy like stars and dust structures. By separating the wavelengths and solely looking at the dust, the scientists were able to view the “skeleton” of the galaxy or regions where gas has coalesced and cooled, creating stellar nurseries where young stars can form.

Viewing the galaxy in this way surprised the scientists. One surprise was that Andromeda is dominated by a large dust ring rather than conventional distinct arms that circle the center of the galaxy. Additionally, a large hole was found within the ring where a dwarf galaxy passed through.

Andromeda via Spitzer. NASA/JPL-Caltech/ UArizona

The team’s results were published in The Astrophysical Journal.

See the full article here .

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NASA Spitzer Infrared Space Telescope was an infrared space telescope launched in 2003 and retired on 30 January 2020.

Spitzer was the third spacecraft dedicated to infrared astronomy, following IRAS (1983) and ISO (1995–98).

It was the first spacecraft to use an Earth-trailing orbit, later used by the Kepler planet-finder.

In keeping with NASA tradition, the telescope was renamed after its successful demonstration of operation, on 18 December 2003. Unlike most telescopes that are named by a board of scientists, typically after famous deceased astronomers, the new name for Spitzer was obtained from a contest open to the general public. The contest led to the telescope being named in honor of astronomer Lyman Spitzer, who had promoted the concept of space telescopes in the 1940s. Spitzer wrote a 1946 report for RAND Corporation describing the advantages of an extraterrestrial observatory and how it could be realized with available or upcoming technology. He has been cited for his pioneering contributions to rocketry and astronomy, as well as “his vision and leadership in articulating the advantages and benefits to be realized from the Space Telescope Program.”

The US$776 million Spitzer Infrared Space Telescope was launched on 25 August 2003 at 05:35:39 UTC from Cape Canaveral SLC-17B aboard a Delta II 7920H rocket. It was placed into a heliocentric (as opposed to a geocentric) orbit trailing and drifting away from Earth’s orbit at approximately 0.1 astronomical units per year (an “Earth-trailing” orbit).

The primary mirror is 85 centimeters (33 in) in diameter, f/12, made of beryllium and was cooled to 5.5 K (−268 °C; −450 °F). The satellite contains three instruments that allowed it to perform astronomical imaging and photometry from 3.6 to 160 micrometers, spectroscopy from 5.2 to 38 micrometers, and spectrophotometry from 55 to 95 micrometers.

By the early 1970s, astronomers began to consider the possibility of placing an infrared telescope above the obscuring effects of Earth’s atmosphere. In 1979, a report from the National Research Council of The National Academy of Sciences , A Strategy for Space Astronomy and Astrophysics for the 1980s, identified a Shuttle Infrared Telescope Facility (SIRTF) as “one of two major astrophysics facilities [to be developed] for Spacelab”, a shuttle-borne platform. Anticipating the major results from an upcoming Explorer satellite and from the Shuttle mission, the report also favored the “study and development of … long-duration spaceflights of infrared telescopes cooled to cryogenic temperatures.”

The launch in January 1983 of the Infrared Astronomical Satellite, jointly developed by the United States, the Netherlands, and the United Kingdom, to conduct the first infrared survey of the sky, whetted the appetites of scientists worldwide for follow-up space missions capitalizing on the rapid improvements in infrared detector technology.

Earlier infrared observations had been made by both space-based and ground-based observatories. Ground-based observatories have the drawback that at infrared wavelengths or frequencies, both the Earth’s atmosphere and the telescope itself will radiate (glow) brightly. Additionally, the atmosphere is opaque at most infrared wavelengths. This necessitates lengthy exposure times and greatly decreases the ability to detect faint objects. It could be compared to trying to observe the stars in the optical at noon from a telescope built out of light bulbs. Previous space observatories (such as IRAS, the Infrared Astronomical Satellite, and ISO, the Infrared Space Observatory) were launched during the 1980s and 1990s and great advances in astronomical technology have been made since then.

Most of the early concepts envisioned repeated flights aboard the NASA Space Shuttle. This approach was developed in an era when the Shuttle program was expected to support weekly flights of up to 30 days duration. A May 1983 NASA proposal described SIRTF as a Shuttle-attached mission, with an evolving scientific instrument payload. Several flights were anticipated with a probable transition into a more extended mode of operation, possibly in association with a future space platform or space station. SIRTF would be a 1-meter class, cryogenically cooled, multi-user facility consisting of a telescope and associated focal plane instruments. It would be launched on the Space Shuttle and remain attached to the Shuttle as a Spacelab payload during astronomical observations, after which it would be returned to Earth for refurbishment prior to re-flight. The first flight was expected to occur about 1990, with the succeeding flights anticipated beginning approximately one year later. However, the Spacelab-2 flight aboard STS-51-F showed that the Shuttle environment was poorly suited to an onboard infrared telescope due to contamination from the relatively “dirty” vacuum associated with the orbiters. By September 1983, NASA was considering the “possibility of a long duration [free-flyer] SIRTF mission”.

Spitzer is the only one of the Great Observatories not launched by the Space Shuttle, as was originally intended. However, after the 1986 Challenger disaster, the Centaur LH2–LOX upper stage, which would have been required to place it in its final orbit, was banned from Shuttle use. The mission underwent a series of redesigns during the 1990s, primarily due to budget considerations. This resulted in a much smaller but still fully capable mission that could use the smaller Delta II expendable launch vehicle.

One of the most important advances of this redesign was an Earth-trailing orbit. Cryogenic satellites that require liquid helium (LHe, T ≈ 4 K) temperatures in near-Earth orbit are typically exposed to a large heat load from Earth, and consequently require large amounts of LHe coolant, which then tends to dominate the total payload mass and limits mission life. Placing the satellite in solar orbit far from Earth allowed innovative passive cooling. The sun shield protected the rest of the spacecraft from the Sun’s heat, the far side of the spacecraft was painted black to enhance passive radiation of heat, and the spacecraft bus was thermally isolated from the telescope. All of these design choices combined to drastically reduce the total mass of helium needed, resulting in an overall smaller and lighter payload, resulting in major cost savings, but with a mirror the same diameter as originally designed. This orbit also simplifies telescope pointing, but does require the NASA Deep Space Network for communications.

The primary instrument package (telescope and cryogenic chamber) was developed by Ball Aerospace & Technologies, in Boulder, Colorado. The individual instruments were developed jointly by industrial, academic, and government institutions, the principals being Cornell University, The University of Arizona, The Smithsonian Astrophysical Observatory , Ball Aerospace, and The NASA Goddard Spaceflight Center. The shorter-wavelength infrared detectors were developed by Raytheon in Goleta, California. Raytheon used indium antimonide and a doped silicon detector in the creation of the infrared detectors. It is stated that these detectors are 100 times more sensitive than what was once available at the beginning of the project during the 1980s. The far-infrared detectors (70–160 micrometers) were developed jointly by the University of Arizona and DOE’s Lawrence Berkeley National Laboratory using Gallium-doped Germanium. The spacecraft was built by Lockheed Martin. The mission was operated and managed by the Jet Propulsion Laboratory and the Spitzer Science Center /The California Institute of Technology.

Warm mission and end of mission

Spitzer ran out of liquid helium coolant on 15 May 2009, which stopped far-IR observations. Only the IRAC instrument remained in use, and only at the two shorter wavelength bands (3.6 μm and 4.5 μm). The telescope equilibrium temperature was then around 30 K (−243 °C; −406 °F), and IRAC continued to produce valuable images at those wavelengths as the “Spitzer Warm Mission”.

Late in the mission, ~2016, Spitzer’s distance to Earth and the shape of its orbit meant the spacecraft had to pitch over at an extreme angle to aim its antenna at Earth. The solar panels were not fully illuminated at this angle, and this limited those communications to 2.5 hours due to the battery drain. The telescope was retired on 30 January 2020 when NASA sent a shutdown signal to the telescope from The NASA Goldstone Deep Space Communications Complex instructing the telescope to go into safe mode. After receiving confirmation that the command was successful, Spitzer Project Manager Joseph Hunt officially declared that the mission had ended.

The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [NASA/ESA Hubble, NASA Chandra, NASA Spitzer, and associated programs.] NASA shares data with various national and international organizations such as from [JAXA]Greenhouse Gases Observing Satellite.