After the Big Bang, the matter in the universe was almost evenly distributed, like a great sea of particles. Gravity tried to put this matter together to form galaxies. But when matter came together, it got very hot, and that heat caused matter to push outward. Thus a kind of chain of \u00abbounces\u00bb was created: gravity attracted it, heat pushed it away, and it started again.<\/p>\n\n\n\n
This tug-of-war game created something akin to sound waves traveling through the universe, like the ripples that form in water when you throw a stone. These waves expanded in the form of bubbles, dragging some of the matter with them.<\/p>\n\n\n\n
About 380,000 years after the Big Bang, the Universe cooled enough for the first atoms to form. At that point, gravity won the game, and it was able to start forming galaxies and other large structures. The bubbles of matter that had formed earlier left a kind of \u00abimprint\u00bb on the distribution of galaxies: these are the acoustic oscillations of baryons, or baryonic acoustic oscillations (BAOs).<\/p>\n\n\n\n
Baryonic acoustic oscillations are bubbles of millions of galaxies that are distributed across a spherical surface, forming like a shell that encloses a very massive supercluster of galaxies at the center.<\/p>\n\n\n\n
Although these structures are subtle, they are very important. By studying them, astronomers can better understand how the Universe expands and how that expansion has changed over time. Comparing the BAOs size at different epochs with their original size when they froze in the early Universe, astronomers can measure how much the Universe has expanded and how much this expansion has been accelerated due to the presence of the dark energy.<\/p>\n\n\n\n
Ho’oleilana is a Hawaiian word meaning \u00abmurmurs of awakening\u00bb and appears in a Hawaiian song of creation that evokes the origin of things.<\/p>\n\n\n\n
It is considered to be a BAO since it is a bubble formed by a multitude of galaxies whose whose radius coincides with what is predicted by the Big Bang theory: 500 million light years.<\/p>\n\n\n\n
At the center of Ho’oleilana is the Bo\u00f6tes supercluster of galaxies. On the surface of this bubble we find millions of galaxies that are grouped together to form groups that in turn come together in larger structures such as the galaxy clusters and superclusters of Coma, Hercules, Leo or the Sloan Great Wall.<\/p>\n\n\n\n
It is important to note that this structure is actually very subtle and that it is totally submerged in the general distribution of galaxies that forms the superstructure of the Universe. Advanced statistical methods are needed to detect this object as an excess over the general distribution of galaxies in the Universe. If we were to consider all galaxies that we can see in this region, the spherical structure would hardly be noticeable. <\/p>\n\n\n\n
The first thing you notice about the model is its spherical shape: we have in our hands the representation of a bubble of galaxies that originated only 380,000 years after the Big Bang.<\/p>\n\n\n\n
The spherical surface is strewn with small balls that represent groups of galaxies, which in turn belong to larger groupings: galaxy clusters and superclusters.<\/p>\n\n\n\n
The gaps in the surface of the sphere are real, although some have been exaggerated to allow access to its interior.<\/p>\n\n\n\n
Inside, in the center, we find a ball of balls: it is the Bo\u00f6tes supercluster. It has been attached to the surface of the bubble with thin pillars that do not actually exist, but which allow the supercluster to be kept in its central position within the bubble.<\/p>\n\n\n\n
On the surface of the bubble, we locate some of the most relevant galaxy clusters:<\/p>\n\n\n
The model has been created by Emilio Terol, from a 3D rendering of the real data made by Daniel Pomar\u00e8de and published in \u00abHo’oleilana: An Individual Baryon Acoustic Oscillation?\u00bb by R. Brent Tully, Cullan Howlett, and Daniel Pomar\u00e8de, The Astrophysical Journal (2023).<\/p>\n\n\n\n
This work has been carried out with a grant from the R&D&I \u2018Proof of Concept\u2019 2022 (PDC2022) call for projects, financed by the European Union through the NextGenerationEU Recovery, Transformation and Resilience Plan. Project\u2019s reference: PDC2022-133930-I00.<\/p>\n\n\n\n