The bumpy road to the discovery of quasars and massive black holes

Invitation to a Midsummer Night's Dream Reading

My intention in this talk is to share a story in which I was very fortunate to participate almost since the beginning, but which is often ignored by the young generation of astronomers. It is the story of the discovery of Massive Black Holes (MBHs). Since everybody in this assembly knows well the subject in its present stage of development, I thought indeed that it could be interesting to show how the ideas that people take for granted presently had such difficulties to emerge and to gain credence. I think that this subject allows, better than any others, to observe that research is not “a long quiet river”, and on the contrary evolves in a non-linear and erratic way, full of mistakes and of dead ends, and that it gives rise to passionate controversies. We will see that the story of MBHs is made of fruitless researches opening on unexpected discoveries, come-backs of visionary models which were first neglected, temporary very fashionable but wrong models, strong debates involving even new physical laws, misinterpretations responsible for decades of stagnation, thousands of papers and nights of the largest telescopes. But finally it opened on a coherent physical model and on a new vision of galaxy evolution. Since it is a long story, I have selected only a few fragments...

Quasars and Galactic Nuclei, a Half-Century Agitated Story

Suzy Collin (Submitted on 27 Apr 2006 (v1), last revised 1 Sep 2006 (this version, v3))

The article is not long in fact. I reproduce below its two figures as lobby cards to advertise its reading!

Figure 1. This radio map of NGC 6251, as published by Readhead, Cohen & Blandford in 1978, shows that a small jet 5 light-years long is aligned with a larger jet of 600 000 light-years, itself aligned with the direction of the radio lobes, separated by 9 millions light-years. The fact that the two jets at the small and intermediate scales are seen only on one side, while the lobes at large scale are almost symmetrical with respect to the galaxy, proves that the side of the jet directed towards us is relativistic boosted, and therefore that the bulk velocity of the jet is very close to the velocity of light. {It was a fundamental discovery to support the cosmological distance hypothesis of quasars}

Figure 2. Cartoon produced by McCray at the Cambridge summer school in 1977 and called “Response of astrophysicists to a fashionable new idea”. I extract a few lines from his paper: “Beyond the accretion radius, r_a , astrophysicists are sufficiently busy to not be influenced by the fashionable new idea. But others, within r_a , begin a headlong plunge towards it... In their rush to be the first, they almost invariably miss the central point, and fly off on some tangent... In the vicinity of the idea, communication must finally occur, but it does so in violent collisions... Some individuals may have crossed the rationality horizon r_s beyond which the fashionable idea has become an article of faith. These unfortunate souls never escape. Examples of this latter phenomenon are also familiar to all of us.”

Pour le lecteur francophone je recommande chaudement la lecture d'un autre texte de Susy Collin-Zahn lui aussi extrêmement pédagogique et informatif sur les controverses autour des quasars et plus généralement autour du modèle cosmologique standard : La théorie du Big Bang rend bien compte des décalages observés publié sur le riche site Science... et pseudo-sciences.