Mapping super massive black holes in the distant Universe

Astronomers have constructed the first map of the Universe based on the positions of supermassive black holes, which reveals the large-scale structure of the Universe.

The map precisely measures the expansion history of the Universe back to when the Universe was less than three billion years old. It will help improve our understanding of ‘Dark Energy’, the unknown process that is causing the Universe’s expansion to speed up.

An artist impression of a quasar. [credit: Hubble telescope].

An artist impression of a quasar. [credit: Hubble telescope].

The map was created by scientists from the Sloan Digital Sky Survey (SDSS), an international collaboration including astronomers from the University of Portsmouth.

As part of the SDSS Extended Baryon Oscillation Spectroscopic Survey (eBOSS), scientists measured the positions of quasars – extremely bright discs of matter swirling around supermassive black holes at the centres of distant galaxies.  The light reaching us from these objects left at a time when the Universe was between three and seven billion years old, long before the Earth even existed.

The map findings confirm the standard model of cosmology that researchers have built over the last 20 years. In this model, the Universe follows the predictions of Einstein’s General Theory of Relativity but includes components that, while we can measure their effects, we do not understand what is causing them.

Along with the ordinary matter that makes up stars and galaxies, Dark Energy is the dominant component at the present time, and it has special properties that mean that it causes the expansion of the Universe to speed up.

Will Percival, Professor of Cosmology at the University of Portsmouth, who is the eBOSS survey scientist said: “Even though we understand how gravity works, we still do not understand everything – there is still the question of what exactly Dark Energy is. We would like to understand Dark Energy further. Not with alternative facts, but with the scientific truth, and surveys such as eBOSS are helping us to build up our understanding of the Universe.”

To make the map, scientists used the Sloan telescope to observe more than 147,000 quasars. These observations gave the team the quasars’ distances, which they used to create a three-dimensional map of where the quasars are.

But to use the map to understand the expansion history of the Universe, astronomers had to go a step further and measure the imprint of sound waves, known as baryon acoustic oscillations (BAOs), travelling in the early Universe. These sound waves travelled when the Universe was much hotter and denser than the Universe we see today. When the Universe was 380,000 years old, conditions changed suddenly and the sound waves became ‘frozen’ in place. These frozen waves are left imprinted in the three-dimensional structure of the Universe we see today.

A slice through largest-ever three-dimensional map of the Universe. Earth is at the left, and distances to galaxies and quasars are labelled by the lookback time to the objects (lookback time means how long the light from an object has been travelling to reach us here on Earth). The locations of quasars (galaxies with supermassive black holes) are shown by the red dots, and nearer galaxies mapped by SDSS are also shown (yellow). The right hand edge of the map is the limit of the observable Universe, from which we see the Cosmic Microwave Background (CMB) - the light “left over” from the Big Bang. Fluctuations in the CMB as observed by the recent ESA Planck satellite mission are shown. The bulk of the empty space in between the quasars and the edge of the observable universe are from the “dark ages”, prior to the formation of most stars, galaxies, or quasars. Credit Anand Raichoor and the SDSS Collaboration.

A slice through largest-ever three-dimensional map of the Universe. Earth is at the left, and distances to galaxies and quasars are labelled by the lookback time to the objects (lookback time means how long the light from an object has been travelling to reach us here on Earth). The locations of quasars (galaxies with supermassive black holes) are shown by the red dots, and nearer galaxies mapped by SDSS are also shown (yellow). The right hand edge of the map is the limit of the observable Universe, from which we see the Cosmic Microwave Background (CMB) – the light “left over” from the Big Bang. Fluctuations in the CMB as observed by the recent ESA Planck satellite mission are shown. The bulk of the empty space in between the quasars and the edge of the observable universe are from the “dark ages”, prior to the formation of most stars, galaxies, or quasars. Credit Anand Raichoor and the SDSS Collaboration.

Using the new map, the observed size of the BAO can be used as a ‘standard ruler’ to measure distances in our universe. “You have metres for small units of length, kilometres or miles for distances between cities, and we have the BAO for distances between galaxies and quasars in cosmology,” explained Pauline Zarrouk, a PhD student at the Irfu/CEA, University Paris-Saclay, who measured the distribution of the observed size of the BAO.

The current results cover a range of times where they have never been observed before, measuring the conditions when the Universe was only three to seven billion years old, more than two billion years before the Earth formed.

The eBOSS experiment continues using the Sloan Telescope, at Apache Point Observatory in New Mexico, USA, observing more quasars and nearer galaxies, increasing the size of the map produced. After it is complete, a new generation of sky surveys will begin, including the Dark Energy Spectroscopic Instrument (DESI) and the European Space Agency Euclid satellite mission. These will increase the fidelity of the maps by a factor of ten compared with eBOSS, revealing the Universe and Dark Energy in unprecedented detail.

4 total comments on this postSubmit yours
  1. With all due respect, maximum light speed is in a vacuum, and Space is not; at the maximum observed redshift it means the objects must be moving at about 80%+ lightspeed away from us.. but consider all the dust, gas, radiation, gravity & unknown stuff out there, to me, the redshift likely is due to all the interstellar stuff it has gone through to reach us. We see redshift every sunrise/sunset when sunlight travels through more of our atmosphere than at noon, but we don’t say the sun is further away at sunrise/sunset, do we? Mr. Hubble backed away from his redshift theory, but it became such a mantra that astronomers just can’t give it up. Suggested reading: the work of astronomers, Arp & Tifft.

    • @Elliot – I think you may misunderstand how redshift works. It has nothing to do with red sunrise/sunset. That phenomenon is due to refraction & reflection of light through our atmosphere. Redshift of light is due to the actual stretching of the light wave length. It is similar to how a train coming toward you, blasting its horn, changes pitch as it passes you. The soundwave is compressed when it’s moving toward you, and stretched after it passes. The faster the movement, the more this is apparent. With light, we see both redshift and blueshift from an object’s apparent movement relative to us.

      Now, we CAN and do detect when light passes through gas and such on the way to us, or bounces off something in our direction, and using spectroscopy we can actually tell what materials those things are made from. So you are correct that that stuff has an effect on the light, but it’s not what causes red/blue shift.

      • The data from SDSS has been very useful. While bigger and better detailed maps are nice (I wanted to see the new 3D view when I came here), the most important news from the SDSS data and actually the most important news in all astronomy rests on this data.

        You mentioned spectroscopy and it has to do with that…

        “Discovery of peculiar periodic spectral modulations in a small fraction of solar type stars” – Ermanno F. Borra and Eric Trottier

        Professor Borra told me it will take some time to verify. It’s been about 8 or 9 months. I have given this serious thought time. If confirmed, I predict every signal will be in 3D and reaffirm the most important truth for all living creatures in the most profound ways possible: “Life is Most Important in Life”.

        In other words, the signals will contain the wisdom of millions and billions of years of evolution beyond us. The we will stop needlessly killing and harming the life here. The needless slaughter of the animals for fun, taste, unneeded nutrition, glamor, fashion, sport, etc., (now frequently described as the Greatest Holocaust of Life in Human History Being Needlessly Committed), will come to an end…. among other things.

        This may be it. It certainly is getting censored. Professor Borra has an excellent reputation and has written, developed, invented, and proved many of the reasons why we see what we do in these surveys with physics. He can’t explain another reason for the periodic spectral modulations…. other than alien life intentionally sending signals. The truth will be in those signals. Each and every one. The silence from Seti\Breakthrough on is staggering.
        We will have to see.

  2. Though of extremely short duration, the expansion is not represented, and while it may be only a slight sliver in the graph, the weight of that process upon the distribution and evolution of the universe is more significant than anything other than the spark at singularity itself, and so should be represented, perhaps even in its theoretical significances.

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