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'Listen' to the Light Echoes From a Black Hole

  • A new sonification turns X-ray data of “light echoes” captured by NASA’s Chandra and Swift X-ray observatories into sound.

  • The light echoes are around V404 Cygni, a binary system where a stellar-mass black hole is in orbit with a “normal” star.

  • Periodically, material around the black hole will generate outbursts in light that propagate outward into space.

  • These data help astronomers learn about the distribution of dust and gas clouds between V404 Cygni and Earth.

One of the surprising features of black holes is that although light (such as radio, visible, and X-rays) cannot escape from them, surrounding material can produce intense bursts of electromagnetic radiation. As they travel outward, these blasts of light can bounce off clouds of gas and dust in space, similar to how light beams from a car’s headlight will scatter off fog.

A new sonification turns these “light echoes” from the black hole called V404 Cygni into sound. Located about 7,800 light-years from Earth, V404 Cygni is a system that contains a black hole, with a mass between five and 10 times the Sun’s, that is pulling material from a companion star in orbit around it. The material is funneled into a disk that encircles the stellar-mass black hole.

This material periodically generates bursts of radiation, including X-rays. As the X-rays travel outward they encounter clouds of gas and dust in between V404 Cygni and Earth and are scattered at various angles. NASA’s Chandra X-ray Observatory and Neil Gehrels Swift Observatory have imaged the X-ray light echoes around V404 Cygni. Because astronomers know exactly how fast light travels and have determined an accurate distance to this system, they can calculate when these eruptions occurred. This data, plus other information, helps astronomers learn more about the dust clouds, including their composition and distances.

V404 Cygni Rings
Illustration showing how the rings seen by Chandra were produced

The sonification of V404 Cygni translates the X-ray data from both Chandra and Swift into sound. During the sonification, the cursor moves outward from the center of the image in a circle. As it passes through the light echoes detected in X-rays (seen as concentric rings in blue by Chandra and red by Swift in the image), there are tick-like sounds and changes in volume to denote the detection of X-rays and the variations in brightness. To differentiate between the data from the two telescopes, Chandra data is represented by higher-frequency tones while the Swift data is lower. In addition to the X-rays, the image includes optical data from the Digitized Sky Survey that shows background stars. Each star in optical light triggers a musical note. The volume and pitch of the note are determined by the brightness of the star.

V404 Cygnus Sonification (Wavelengths)

More sonifications of astronomical data, as well as additional information on the process, can be found at the "A Universe of Sound" website:

These sonifications were led by the Chandra X-ray Center (CXC) and included as part of NASA's Universe of Learning (UoL) program. The collaboration was driven by visualization scientist Kimberly Arcand (CXC), astrophysicist Matt Russo, and musician Andrew Santaguida (both of the SYSTEM Sounds project). NASA's Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory's Chandra X-ray Center controls science from Cambridge Massachusetts and flight operations from Burlington, Massachusetts. NASA's Universe of Learning materials are based upon work supported by NASA under cooperative agreement award number NNX16AC65A to the Space Telescope Science Institute, working in partnership with Caltech/IPAC, Center for Astrophysics | Harvard & Smithsonian, and the Jet Propulsion Laboratory.


Fast Facts for V404 Cygni:
Credit  X-ray: Chandra: NASA/CXC/U.Wisc-Madison/S. Heinz et al.; Swift: NASA/Swift/Univ. of Leicester/A. Beardmore; Optical: DSS; Sonification: NASA/CXC/SAO/K.Arcand, SYSTEM Sounds (M. Russo, A. Santaguida)
Release Date  November 21, 2022
About the Sound 
  • This is an inside-out scan of the light echo rings formed by dust scattering and the background stars.

  • Dust scattering rings
    • The sound is generated by a series of tick-like sounds. The volume and density of ticks is controlled by the ring brightness.
    • Listening to the pattern of rings in this way traces the density of dust clouds that the light has scattered off of on its way towards Earth.
    • The sound generated by the Swift X-ray data is represented as lower frequencies.
    • The Chandra X-ray data represents higher frequency light and its corresponding sound is limited to higher frequencies.
  • Background stars (DSS Optical data)
    • Each visible light star triggers a musical note. The volume and pitch of the note are determined by the brightness of the star. Brighter stars are louder and higher pitched.

    Scale  Image is about 35 arcmin (80 light-years) across.
    Category  Black Holes
    Coordinates (J2000)  RA 20h 24m 03s | Dec +33° 52´ 02"
    Constellation  Cygnus
    Observation Date  2 observations: July 13th and 29th, 2015
    Observation Time  18 hours 51 minutes
    Obs. ID  17701, 17704
    Instrument  ACIS
    References Heinz, S., et al., ApJ, 2016, 825, 15; arXiv:1605.01648
    Color Code  X-ray: Chandra: blue & teal, Swift: red, green, blue; Optical: red, green blue
    Distance Estimate  About 7,800 light-years
    distance arrow
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