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Interpretation of Blazar Flux Variations as Music  Dr. James R. Webb Department of Physics Florida International University And the SARA Observatory

Abstract Blazars are believed to be distant galaxies in the process of formation.  They emit electromagnetic radiation (light) over the entire electromagnetic spectrum from radio waves to gamma-rays. The emission varies with time in most frequency ranges and the causes for the variation are yet to be adequately explained.  Astronomers have been monitoring these objects with optical telescopes for over 50 years now and we have collected a large database of brightnesses over these fifty years.  This paper presents some of these light curves, and adopts a computational method to translate the brightness fluctuations into musical tones.  These tones are then converted to sound using a midi synthesizer on a PC.

Interpreting Astronomical Data as Sound Terenzi (1988) used radio observations of galaxy UGC 6697 to create music.  This work resulted in a popular CD called “Music from the Galaxies” by Fiorella Terenzi and published by Island records.  I used the CD in several public lectures about radio galaxies and got excellent response from the attendees.  Terenzi (1997) suggested I do something with the quasar light curves, and this suggestion resulted in the work presented here.

Observations The light curves used in this project are optical observations of four well-observed Blazars extending back to around the mid 1970’s. These objects are AO 0235+164, 3C 120, 3C 345, and PKS 1156+295.  Most of the data were gathered with the 0.76 meter telescope at the University of Florida’s Rosemary Hill Observatory (see Webb et al. 1988 and references within) by a variety of observers.  Photographic plates with special filters were used to collect the data, which were then reduced using an Iris photometer and calibrated with nearby stars.  Figure 1 shows the optical light curves of the four sources in this work (from Webb et al 1988).

Optical Lightcurve of PKS 1156+295

Conversion to Musical Tones A program was written in IDL which reads in the optical magnitude and the time of observation and converts them to musical notes in the key of C. Range of 2.5 octaves from the A below middle C to the C two octaves above middle C. The program the determines the maximum and minimum magnitudes of the light curve, then assigns the appropriate musical notes to each magnitude value  (A1 through C3).  Figure 2 shows this association schematically.

From Data to Music There are three separate aspects of music, the pitch or frequency, the intensity, and the timing, Since we had no spectral information, I decided to transform the intensities to pitches.  The timing was transformed directly to note durations.

Figure 2. Conversion to Musical Tones.

Timing of Musical Notes

IDL Code “Music.pro”

Music.pro (Cont’d)

Creating the Sounds The output from the IDL program was input by hand into a program called Cakewalk Home Studio on a PC. The timing was somewhat modified by the Home Studio program when inputting the calculated notes into the Staff window, sometimes putting notes on top of each other to reconcile the timing.  Once the data was input for each object, the Home Studio midi voice FX (goblins) was used to play back the music. The tone variations represent changes in brightness, while the duration of the tones and the time between them represents the observing frequencies.

Uses for Quasar Music Although the rendering of brightness fluctuations of quasars into sonic fluctuations may not have any intrinsic scientific value, it is valuable for educational purposes. Useful for Public Lectures since many people are fascinated with the concept that you can “hear” the music created by distant quasars emitting light billions of years ago in collaboration with observers here on Earth. The timing is set by the orbital motion of the Earth around the Sun, the rotation of the Earth and by the phases of the Moon. This “Cosmic Orchestration” resulted in some intriguing sounds that can be further used in more sophisticated compositions.  b

Quasar Music CD The sounds you are hear on the “Quasar CD” is the result of the rendering process described in this paper.  These sounds are totally un-orchestrated by the author, other than the process described above, so any tonal or harmonic structure results from the “cosmic Orchestration” described above.  This music has become an important part of my public lecture entitled  “An Evening at the Edge of the Universe” which presents to lay audiences the exotic objects at the very edges of the visible universe, from radio galaxies out to quasars, and combines concepts like the expanding Universe, synchrotron radiation (as heard in “Music from the Galaxies”) to quasar models and their brightness variations as heard in the quasar music.

The Florida International University Public Lecture Series 6 events per month – free and open to the public. Welcome Back Star Party 4 Public Lectures Summer/Winter star Party Lectures are original scientific talks aimed at the general public, college and school students. Star parties feature ½ mini-lectures and music segments ranging from acoustic guitar music to electronic (quasar) music.

Example Talk Topics Sample Presentations I have indicated here eight presentations which I have given to amateur astronomical groups and general public audiences. I generally speak for 45 minutes and allow approximately 15 minutes for questions and discussion. I am happy to address all questions pertaining to astronomy or physics even if they are not immediately related to the presentation. I am also willing to speak on topics in astronomy not covered in these preset lectures and can tailor the lecture to the group by age and or education as desired. An Evening at the Edge of the Universe This program is a multimedia presentation introducing laymen to the world of extragalactic astronomy and cosmology. I use music and slides help illustrate our current knowledge of the farthest reaches of the Universe. The discussion includes exotic objects known as quasars, galaxy formation and the science of cosmology. A discussion of Black holes in this context usually follows. The Scientific Search for Life in the Universe This lecture explores the current state of the scientific search for extraterrestrial life. It includes background so the audience will understand why and how serious scientists attack this important topic. I discuss life on Earth, the search for radio waves from extraterrestrial civilizations, and the problem of UFO's. All topics are discussed in a scientific context including the latest information and observations. I also give handouts containing related web sites and books in case the audience is interested in pursuing the subject further. Asteroids, Impacts and the Earth The possibility of an asteroid or comet hitting the Earth is discussed. I discuss historical impacts, recent impacts in the Solar System, and possible future impacts in a scientific context. I also discuss current astronomical programs designed to map near Earth asteroids. The Strange World of Relativity Albert Einstein's Special and General Theory of Relativity are introduced and explained In terms a non-scientific audience can understand. This lecture was crafted from years of explaining Relativity in College courses, at both the undergraduate and graduate level. I concentrate on concepts and only occasionally refer to mathematics. When I do refer to mathematics, it is an attempt to show the audience how relativity is actually used. Gravitational Waves: Seeing the Universe in a new 'Light' This lecture starts out with a discussion of gravity, explains Einstein's theory of gravity, and goes on to describe the nature of gravitational waves. We also discuss the detection and the possibilities for increasing our understanding of the universe once we detect them. Lecture: It's About Time! Dr. Webb discusses the nature of time in physics. Going from thermodynamics, to quantum, to relativity, explaining each concept clearly to a general audience. Pulsars: Lighthouses in the Universe This talk was requested by the Southern Cross Astronomical Society. In it, Dr. Webb explains neutron stars, magentic fields, the detection of Pulsars, and the newest twist on pulsars: Magnetars! The Accelerating Universe The newest observations and the latest theoretical developments in cosmology are discussed. Dr. Webb puts the new stuff in context with a detailed explanation of the basics of cosmology and the Big Bang Theory.

Example Star Party Themes FIU’s Annual Key West Style Star Party. Featuring Jimmy Buffett Music, Key Lime pies and non-alcoholic margatritas. Astronomy Music Star party. Features astronomy music and live acoustic guitar music. Martian Opposition Star Party. 2001 A Space Odyssey Star Party.

Acknowledgements JRW would like to thank all of the observers who participated in the Rosemary Hill Monitoring program at the University of Florida throughout the years during which quasar monitoring program was collecting data. That program was supported by a succession of NSF grants.  JRW would also like to thank Dr. Fiorella Terenzi for pioneering the interface between music and science and for suggesting this work to me..

References Deeming. J., 1975, Astrophysics and Space Science, Vol. 36, p.137 Schmidt 1962, Ap. J., 136..684. Terenzi, F. 1988, Ph.D thesis to the University of Milan, “Design and Realization of an integrated map-C music for the composition of a musical score and the numerical synthesis of sound” Terenzi, “Music from the Galaxies” 1991 Island Records. Webb et al. 1988, A.J., 95, 374. Webb 1990, A.J. 99, 49.