The complex puzzle known as little red dots has become more complete since their initial discovery by NASA’s James Webb Space Telescope in 2022. Now a particular little red dot’s spectrum is helping connect many of the pieces.

A team of astronomers led by Vasily Kokorev at the University of Texas at Austin identified the lucky dot in question: GLIMPSE-17775. By carefully analyzing the dot’s spectrum captured by Webb — the deepest spectrum to date of a little red dot — the research team has identified multiple lines of evidence, all of which support the interpretation that GLIMPSE-17775 is a supermassive black hole enveloped in a dense cocoon of partially ionized gas, a model referred to as the BH* (black hole star) scenario. A paper describing the results was published today in The Astrophysical Journal.

“I think part of the scientific community is converging on a singular picture — that little red dots can be explained by black hole star models. But none of the previous little red dots have all of the pieces of evidence in the same place,” said Kokorev, lead author of the study. “With GLIMPSE-17775 we can test these models because of how deep and amazing this source’s spectrum is.”

Image: Abell S1063 with Pullout of GLIMPSE-17775 (NIRCam Image)

Connecting puzzle pieces

Soon after Webb first began science operations, it discovered a new, mysterious type of object in the very early universe – abundant red objects that emerged about 600 million years after the big bang. Scientists have explored multiple explanations for these little red dots, including the black hole star scenario.

A set of fortunate circumstances brought about this new, elaborate spectrum of a little red dot. The little red dot that would come to be known as GLIMPSE-17775 was fortunately included in Webb’s imaging and spectroscopy efforts for a project that sought to look for Population III stars and faint galaxies in galaxy cluster Abell S1063. This little red dot is more distant than the galaxy cluster and magnified by gravitational lensing. (GLIMPSE-17775 has a cosmological redshift of 3.5, meaning it existed about 1.8 billion years after the big bang.)

While Webb provided a 30-hour spectrum of the little red dot, the effect of gravitational lensing made it equivalent to 80 hours of telescope time. This combination of Webb’s infrared sensitivity and nature’s own “magnifying glass” amplified the amount of detail that could be gleaned from GLIMPSE-17775. The result was more than 40 spectral lines from this small, red source, which is the most detailed little red dot spectrum to date.

“When we saw the spectrum for the first time, it was like having all the pieces of a puzzle scattered on the floor,” said Kokorev. “We picked up each piece of the puzzle, measured the lines, and started combining the different pieces into a mosaic. Maybe a few pieces looked like nothing at first, but then a couple of them came together, and we realized that there was something there.”

The spectroscopic data collected by Webb contains multiple lines of evidence that support the interpretation that little red dot GLIMPSE-17775 is a black hole star: a rapidly accreting, or growing, black hole enveloped in a dense gas cocoon, which is reprocessing the light emitted from near the black hole and producing the features seen in the spectrum.

Image: Evidence of a ‘Black Hole Star’

Lines of evidence

Among the 40-plus lines that the team detected in GLIMPSE-17775’s spectrum were various independent indicators that all align with the BH* scenario. For example, the team found that many of the spectral lines, such as hydrogen, oxygen, and helium, do not fit a simple model of a rotating gas cloud. Instead, the best fit model includes a broadening effect known as electron scattering, a telltale sign that a dense, layered gas cocoon is enshrouding this source. 

The strength and ratios of certain lines to each other, most notably the 16 iron lines that compose what the team has dubbed an “iron forest” and certain oxygen lines, require a high-energy source to produce them, like a rapidly accreting black hole. Additionally, astronomers noted the fluorescence and absorption of helium in the spectrum, both of which individually suggest that there is a dense medium enveloping a powerful source.

The BH* scenario not only fits GLIMPSE-17775; it also accounts for why most little red dots are faint in X-rays, since any such emission is likely absorbed by the dense gas cocoon.

One missing element of the GLIMPSE-17775 puzzle piece is the part of the spectrum that would reveal what’s known as a Balmer break, or a strong dip in the emitted light that’s a signature characteristic of little red dots. To build a more comprehensive understanding of this little red dot, the team incorporated ancillary data from two observing programs that used NASA’s Hubble Space Telescope: the Frontier Fields and BUFFALO (Beyond Ultra-deep Frontier Fields And Legacy Observations) programs.

The Webb and Hubble data together help explain why the Balmer break is weaker than what typically is found in other little red dots: A giant host galaxy is surrounding GLIMPSE-17775. Although a little red dot’s host galaxy is not something that has been usually seen at such scale before, it isn’t inconsistent with the dense gas cocoon model. The black hole star model of little red dots attributes excess blue light to stars in the host galaxy.

When Webb first discovered little red dots, some researchers thought these objects had “broken cosmology,” unsure how galaxies could have grown so big so quickly in the early universe to account for all this light coming from their stars. However, the team believes the GLIMPSE-17775 puzzle piece fits nicely in the existing framework of the universe’s evolutionary history, because black hole masses don’t need to be as high in order to explain the broad emission lines.

“Everything fits, nothing is broken, and I think that makes the puzzle that is our universe even better,” said Kokorev. “Looking ahead, I’m eager to dive deeper and learn about what is powering the central engines of little red dots. While we think it’s a black hole, there are some other interesting theories being proposed, which is exciting. Maybe in a year or two, we’ll have the final answer to what powers these sources.” 

The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).

To learn more about Webb, visit:

https://science.nasa.gov/webb

Downloads & Related Information

The following sections contain links to download this article’s images and videos in all available resolutions followed by related information links, media contacts, and if available, research paper and Spanish translation links.

Related Links

Read more: Black Hole Basics

Explore more: ViewSpace | Black Holes: Searching for the unseen

Watch: NASA Black Hole Visualization Takes Viewers Beyond the Brink

Watch: What Webb Learns from Light

Explore more: NASA’s Universe of Learning: Black Hole Resources

Read more: NASA Connects Little Red Dots with Chandra, Webb

More Webb News

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A compact, multifrequency radar built by a team at NASA’s Jet Propulsion Laboratory will make it easier to collect information about dynamic cloud systems. Called CloudCube, this new instrument simultaneously probes the atmosphere with three radar signals, spanning 36 to 240 GHz, for optimized sensitivity to a wide range of water droplet and ice particle sizes. 

Built with funding from NASA’s Earth Science Technology Office Instrument Incubator Program, CloudCube transmits and receives Ka-, W-, and G-band signals, making it the first compact radar system capable of simultaneously probing meteorological targets at wavelengths spanning approximately one to ten millimeters. Researchers will be able to combine information from the three signals to learn more about the initiation and evolution of precipitation, as well as cloud microphysics and radiative properties.

“We’re making a low-power, low-mass instrument to facilitate new cost-efficient missions for atmospheric observations. Building a multi-frequency radar, especially at G-band, is very novel,” said Raquel Rodriguez Monje, a systems engineer at JPL and principal investigator for CloudCube.

Each of CloudCube’s three signals observes a different element of cloud physics. Ka-band radar signals are ideal for collecting precipitation profiles; W-band radar signals are preferred for measuring cloud particles that give rise to precipitation; and G-band radar signals, which have never been collected from a space-based instrument, are ideal for measuring ice and liquid water content inside very light clouds (a paper describing this measurement can be found here).

Probing the atmosphere simultaneously with three signals allows researchers to collect data on all these cloud features at once, which is valuable for improving weather forecasts and especially climate modeling. CloudCube leverages innovations in millimeter-wave hardware to pack three radar modules–one for each signal–within a single compact system.

One CloudCube innovation concerns the specialized components required to transmit G-band power from a compact, low-power instrument. The detection of cloud signals requires high transmit power, which CloudCube achieves by combining the outputs of multiple high-efficiency frequency-multiplication devices that allow the instrument to generate hundreds of milliWatts at 240 GHz. Another innovation of CloudCube is that it was designed to use as few radio frequency components as possible to reduce its mass and power consumption, which could lower the cost of future Earth-observing orbital instruments.

Flying an instrument equipped with G-band radar in space will be a new capability and will allow researchers to achieve greater spatial resolution and sensitivity in the study of cloud microphysical processes.

“Basically, we’re weighing clouds using these combinations of frequencies in a way that we couldn’t do before we had the G-band,” said Matt Lebsock, a researcher at JPL and co-investigator for CloudCube.

The instrument has been tested in the field. A ground-based prototype of CloudCube’s G-band channel operated continuously for 11 months during the Department of Energy’s Cloud and Precipitation Experiment at Kennaook (CAPE-K) campaign. CloudCube also participated in the Eastern Pacific Cloud Aerosol Precipitation Experiment, a ground campaign sponsored by the Department of Energy. A paper describing the results of that experiment can be found here.

Most recently, CloudCube successfully operated all three frequency bands from NASA’s Gulfstream III aircraft and collected its first airborne observations of snowfall as part of the North American Upstream Feature-Resolving and Tropopause Uncertainty Reconnaissance Experiment campaign—a NASA-funded campaign designed to improve forecasts of high-impact winter weather. The CloudCube team is currently calibrating and processing the data for public release.

For additional details, see the entry for this project on NASA TechPort.

Project Lead: Dr. Raquel Rodriguez Monje, NASA’s Jet Propulsion Laboratory

Sponsoring Organization: NASA’s Earth Science Technology Office Instrument Incubation Program

The complex puzzle known as little red dots has become more complete since their initial discovery by NASA’s James Webb Space Telescope in 2022. Now a particular little red dot’s spectrum is helping connect many of the pieces.

A team of astronomers led by Vasily Kokorev at the University of Texas at Austin identified the lucky dot in question: GLIMPSE-17775. By carefully analyzing the dot’s spectrum captured by Webb — the deepest spectrum to date of a little red dot — the research team has identified multiple lines of evidence, all of which support the interpretation that GLIMPSE-17775 is a supermassive black hole enveloped in a dense cocoon of partially ionized gas, a model referred to as the BH* (black hole star) scenario. A paper describing the results was published today in The Astrophysical Journal.

“I think part of the scientific community is converging on a singular picture — that little red dots can be explained by black hole star models. But none of the previous little red dots have all of the pieces of evidence in the same place,” said Kokorev, lead author of the study. “With GLIMPSE-17775 we can test these models because of how deep and amazing this source’s spectrum is.”

Image: Abell S1063 with Pullout of GLIMPSE-17775 (NIRCam Image)

Connecting puzzle pieces

Soon after Webb first began science operations, it discovered a new, mysterious type of object in the very early universe – abundant red objects that emerged about 600 million years after the big bang. Scientists have explored multiple explanations for these little red dots, including the black hole star scenario.

A set of fortunate circumstances brought about this new, elaborate spectrum of a little red dot. The little red dot that would come to be known as GLIMPSE-17775 was fortunately included in Webb’s imaging and spectroscopy efforts for a project that sought to look for Population III stars and faint galaxies in galaxy cluster Abell S1063. This little red dot is more distant than the galaxy cluster and magnified by gravitational lensing. (GLIMPSE-17775 has a cosmological redshift of 3.5, meaning it existed about 1.8 billion years after the big bang.)

While Webb provided a 30-hour spectrum of the little red dot, the effect of gravitational lensing made it equivalent to 80 hours of telescope time. This combination of Webb’s infrared sensitivity and nature’s own “magnifying glass” amplified the amount of detail that could be gleaned from GLIMPSE-17775. The result was more than 40 spectral lines from this small, red source, which is the most detailed little red dot spectrum to date.

“When we saw the spectrum for the first time, it was like having all the pieces of a puzzle scattered on the floor,” said Kokorev. “We picked up each piece of the puzzle, measured the lines, and started combining the different pieces into a mosaic. Maybe a few pieces looked like nothing at first, but then a couple of them came together, and we realized that there was something there.”

The spectroscopic data collected by Webb contains multiple lines of evidence that support the interpretation that little red dot GLIMPSE-17775 is a black hole star: a rapidly accreting, or growing, black hole enveloped in a dense gas cocoon, which is reprocessing the light emitted from near the black hole and producing the features seen in the spectrum.

Image: Evidence of a ‘Black Hole Star’

Lines of evidence

Among the 40-plus lines that the team detected in GLIMPSE-17775’s spectrum were various independent indicators that all align with the BH* scenario. For example, the team found that many of the spectral lines, such as hydrogen, oxygen, and helium, do not fit a simple model of a rotating gas cloud. Instead, the best fit model includes a broadening effect known as electron scattering, a telltale sign that a dense, layered gas cocoon is enshrouding this source. 

The strength and ratios of certain lines to each other, most notably the 16 iron lines that compose what the team has dubbed an “iron forest” and certain oxygen lines, require a high-energy source to produce them, like a rapidly accreting black hole. Additionally, astronomers noted the fluorescence and absorption of helium in the spectrum, both of which individually suggest that there is a dense medium enveloping a powerful source.

The BH* scenario not only fits GLIMPSE-17775; it also accounts for why most little red dots are faint in X-rays, since any such emission is likely absorbed by the dense gas cocoon.

One missing element of the GLIMPSE-17775 puzzle piece is the part of the spectrum that would reveal what’s known as a Balmer break, or a strong dip in the emitted light that’s a signature characteristic of little red dots. To build a more comprehensive understanding of this little red dot, the team incorporated ancillary data from two observing programs that used NASA’s Hubble Space Telescope: the Frontier Fields and BUFFALO (Beyond Ultra-deep Frontier Fields And Legacy Observations) programs.

The Webb and Hubble data together help explain why the Balmer break is weaker than what typically is found in other little red dots: A giant host galaxy is surrounding GLIMPSE-17775. Although a little red dot’s host galaxy is not something that has been usually seen at such scale before, it isn’t inconsistent with the dense gas cocoon model. The black hole star model of little red dots attributes excess blue light to stars in the host galaxy.

When Webb first discovered little red dots, some researchers thought these objects had “broken cosmology,” unsure how galaxies could have grown so big so quickly in the early universe to account for all this light coming from their stars. However, the team believes the GLIMPSE-17775 puzzle piece fits nicely in the existing framework of the universe’s evolutionary history, because black hole masses don’t need to be as high in order to explain the broad emission lines.

“Everything fits, nothing is broken, and I think that makes the puzzle that is our universe even better,” said Kokorev. “Looking ahead, I’m eager to dive deeper and learn about what is powering the central engines of little red dots. While we think it’s a black hole, there are some other interesting theories being proposed, which is exciting. Maybe in a year or two, we’ll have the final answer to what powers these sources.” 

The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).

To learn more about Webb, visit:

https://science.nasa.gov/webb

Downloads & Related Information

The following sections contain links to download this article’s images and videos in all available resolutions followed by related information links, media contacts, and if available, research paper and Spanish translation links.

Related Links

Read more: Black Hole Basics

Explore more: ViewSpace | Black Holes: Searching for the unseen

Watch: NASA Black Hole Visualization Takes Viewers Beyond the Brink

Watch: What Webb Learns from Light

Explore more: NASA’s Universe of Learning: Black Hole Resources

More Webb News

More Webb Images

Webb Science Themes

Webb Mission Page

The post NASA Webb Finds Strongest Evidence Yet for ‘Black Hole Stars’ appeared first on NASA Science.

A compact, multifrequency radar built by a team at NASA’s Jet Propulsion Laboratory will make it easier to collect information about dynamic cloud systems. Called CloudCube, this new instrument simultaneously probes the atmosphere with three radar signals, spanning 36 to 240 GHz, for optimized sensitivity to a wide range of water droplet and ice particle sizes. 

Built with funding from NASA’s Earth Science Technology Office Instrument Incubator Program, CloudCube transmits and receives Ka-, W-, and G-band signals, making it the first compact radar system capable of simultaneously probing meteorological targets at wavelengths spanning approximately one to ten millimeters. Researchers will be able to combine information from the three signals to learn more about the initiation and evolution of precipitation, as well as cloud microphysics and radiative properties.

“We’re making a low-power, low-mass instrument to facilitate new cost-efficient missions for atmospheric observations. Building a multi-frequency radar, especially at G-band, is very novel,” said Raquel Rodriguez Monje, a systems engineer at JPL and principal investigator for CloudCube.

Each of CloudCube’s three signals observes a different element of cloud physics. Ka-band radar signals are ideal for collecting precipitation profiles; W-band radar signals are preferred for measuring cloud particles that give rise to precipitation; and G-band radar signals, which have never been collected from a space-based instrument, are ideal for measuring ice and liquid water content inside very light clouds (a paper describing this measurement can be found here).

Probing the atmosphere simultaneously with three signals allows researchers to collect data on all these cloud features at once, which is valuable for improving weather forecasts and especially climate modeling. CloudCube leverages innovations in millimeter-wave hardware to pack three radar modules–one for each signal–within a single compact system.

One CloudCube innovation concerns the specialized components required to transmit G-band power from a compact, low-power instrument. The detection of cloud signals requires high transmit power, which CloudCube achieves by combining the outputs of multiple high-efficiency frequency-multiplication devices that allow the instrument to generate hundreds of milliWatts at 240 GHz. Another innovation of CloudCube is that it was designed to use as few radio frequency components as possible to reduce its mass and power consumption, which could lower the cost of future Earth-observing orbital instruments.

Flying an instrument equipped with G-band radar in space will be a new capability and will allow researchers to achieve greater spatial resolution and sensitivity in the study of cloud microphysical processes.

“Basically, we’re weighing clouds using these combinations of frequencies in a way that we couldn’t do before we had the G-band,” said Matt Lebsock, a researcher at JPL and co-investigator for CloudCube.

The instrument has been tested in the field. A ground-based prototype of CloudCube’s G-band channel operated continuously for 11 months during the Department of Energy’s Cloud and Precipitation Experiment at Kennaook (CAPE-K) campaign. CloudCube also participated in the Eastern Pacific Cloud Aerosol Precipitation Experiment, a ground campaign sponsored by the Department of Energy. A paper describing the results of that experiment can be found here.

Most recently, CloudCube successfully operated all three frequency bands from NASA’s Gulfstream III aircraft and collected its first airborne observations of snowfall as part of the North American Upstream Feature-Resolving and Tropopause Uncertainty Reconnaissance Experiment campaign—a NASA-funded campaign designed to improve forecasts of high-impact winter weather. The CloudCube team is currently calibrating and processing the data for public release.

For additional details, see the entry for this project on NASA TechPort.

Project Lead: Dr. Raquel Rodriguez Monje, NASA’s Jet Propulsion Laboratory

Sponsoring Organization: NASA’s Earth Science Technology Office Instrument Incubation Program

The post NASA’s CloudCube Pioneers Miniaturized Radar to Study Clouds, Precipitation appeared first on NASA Science.