#JUMP INTO A BLACK HOLE SIMULATION SERIES#

Figure 1: This diagram shows evolution of the haloes from left to right with time. Our simulation showed for the first time that this gas fragments and forms a large cluster of black hole-induced metal-poor stars which surround it (Figure 1, below).

Radiation from the accretion disk around the black hole then quickly ionizes the surrounding gas, which actually promotes the production of molecular hydrogen in the still-collapsing gas around the black hole ( Abel et al. Instead, the central clump coalesces into a single transitory massive star, which, once it burns rapidly through its life, quickly collapses into a black hole seed with a mass of up to 20,000 times the mass of our Sun. While this is a surprising scenario that could not happen in our present day metal-rich Universe, simulations show that it is possible for such a massive “quasi-star' to form during the Cosmic Dawn, fuse hydrogen normally for a short period of time, and then disperse, “leaving behind the naked seed with a mass of thousands to hundred thousands of solar masses.” (From Volonteri and Bellovary, 2012, Section 2.2). This leaves a much more homogeneous gas cloud to collapse uniformly into one large central clump without fragmenting into smaller proto-stars. However, our simulations show that in rare configurations, in metal-free regions of the early Universe, starlight from a nearby galaxy can break up molecular hydrogen back into atomic hydrogen. Lone hydrogen atoms, aka atomic hydrogen, cool very inefficiently so the size of stellar cores is usually modulated by the presence or absence of molecular hydrogen (H 2) and what astronomers call metals: elements with an atomic number greater than helium. These 'atomic cooling haloes' cool much more efficiently because more complex molecules and atoms have more complex electron shell structures, giving a wider range of quantized energy levels that electrons can jump through, radiating energy via emitted photons in the process. The slower the cooling rate, the larger the mass of gas that ends up in each stellar core ( Jeans mass). Stars form from clouds of gravitationally collapsing gas as the clouds gradually cool by radiating away their heat. We then made predictions about how the formation and evolution of a massive black hole seed would progress and how it might look if seen through the forthcoming James Webb Space Telescope (JWST).

#JUMP INTO A BLACK HOLE SIMULATION SERIES#

My collaborators and I investigated this second 'massive star' scenario with a series of cosmological simulations. More than one possible answer to this accretion conundrum has been proposed. For example, one possibility is that the original stellar somehow remnant accreted mass more quickly than the Eddington limit allows.Ī second possibility, which I and my collaborators investigated, is that the progenitor star was significantly more massive than those we see in the local Universe. Specifically, the theory states that some of the kinetic energy of the gas that falls into a black hole is converted into radiation which pushes back against the infalling gas, thus establishing an Eddington Limit for the maximum accretion rate-a rate far exceeded by the SMBH at the center of M87. Most theories predict that stellar remnants serve as the initial seeds for massive black hole formation, but the Mortlock quasar accumulated so much mass so early in the lifetime of the Universe that, according to the classical Eddington theory of accretion, there would not have been enough time for the remnant of a normal star to become so large. By that time it already weighed in at about 2 billion solar masses ( Mortlock, et al., 2011). The earliest SMBH discovered powers a bright quasar and was observed a redshift of about z=7.1 (about 760 million years after the Big Bang) during a period of the Universe’s 13.75-billion-year history called the Epoch of Reionization, or Cosmic Dawn.

We know that the black hole they studied, the one at the center of the galaxy Messier 87 (or M87) in the Virgo Galaxy Cluster, is around three and a half billion times as massive as our own Sun, but how did it accumulate so much mass and, more generally, how and when did these massive black holes form? Last year the astrophysics community celebrated the first direct image of a supermassive black hole (SMBH) by the Event Horizon Telescope.

Jump into a black hole simulation