General AstronomyLarge Scale Structure

of the Universe

Large Scale StructureBy this time you should be realizing

that the universe is a bit bigger than your home planet, solar system, etc.

The amount of ‘real estate’ keeps getting larger, but is there a pattern or structure at the largest scales?

Building Blocks• Stars are collected into clouds or

clusters or galaxies– The Sun is just one of the 200 billion

or more stars in the Milkyway Galaxy• Are there larger building blocks?

The Home Galaxy

From An Atlas of the Universe by Richard Powell

The Local GroupThe Milkyway is a member of a grouping of galaxies, spirals, irregulars, dwarf ellipticals. This is known as the Local Group. It is dominated by the Milkyway and the Andromeda Galaxy

From An Atlas of the Universe by Richard Powell

A 3D view gives a better pictureThe Local Group

ClustersThe Local Group is being attracted by the gravity of an even larger grouping of galaxies.

The nearest cluster of galaxies is the Virgo Cluster. It is composed of about a 1000 galaxies and it is likely that, in time, the Local Group will be absorbed (cannibalized?) into the Virgo Cluster.

Just the local neighborhood

The Virgo Cluster and the Local group are just the "smaller" structures.

Several hundred clusters are gathered into the Virgo SuperCluster.

Virgo SuperCluster

From An Atlas of the Universe by Richard Powell

Neighboring SuperClusters

From An Atlas of the Universe by Richard Powell

Here is a map of just some of the superclusters

If we look at a 'slice' it appears as if some structures are forming.

Walls and voids spotted by knots where the superclusters are located.

The Observable Universe

From An Atlas of the Universe by Richard Powell

At the largest scale, there appears to be a filamentary structure.

Hubble Ultra Deep FieldThe Hubble Ultra-Deep Field (HUDF) is an image of a small region of space in the constellation Fornax, composited from Hubble Space Telescope data.

It is the deepest image of the universe ever taken, looking back approximately 13 billion years (between 400 and 800 million years after the Big Bang)

Zoom in on a small section

Hubble Ultra Deep Field

Galaxies – over 10,000 in the HUDF!

Hubble Extreme Deep Field

z v/c R(t) 1/R(t)1.55 0.7334 0.392 2.55

8.5 0.9781 0.105 9.508.6 0.9785 0.104 9.608.7 0.9790 0.103 9.70

10.3 0.9845 0.088 11.30

Formation of FilamentsSimulations from The Center for Cosmological Physics

The frames illustrate the formation of clusters and large-scale filaments in the Cold Dark Matter model with dark energy. The frames show the evolution of structures in a 43 million parsec box from redshift of 30 (when the age of the Universe was less than 1% of its current age) to the present epoch

Formation of a Group of Galaxies

Simulations from The Center for Cosmological Physics

Formation of a group of galaxies quite similar to our Local Group in which our galaxy, the Milky Way, is approaching our biggest neighbor the Andromeda Galaxy. The region shown here is 1/10 of the box shown in the previous slide and is equal to 4.3 megaparsecs.Small-mass objects form first at z>5, they quickly grow in size and violently merge with each other, creating increasingly larger and larger system. This galactic "cannibalism" persists even to the present day epoch (z=0).

The panels show a disk galaxy in the process of formation at the epoch where the virtual universe of the simulation was "only" one and a half billion years old. The panels show (clock-wise from the top left) regions of 36 kiloparsec, 72 kiloparsec, 144 kiloparsec, 288 kiloparsec, respectively. The young galaxy forms in a high-density peak in which several large-scale filaments of matter intersects. These filaments deliver a fresh supply of gas and dark matter to the galaxy. The accreting gas fuels very active star formation, while accreted dark matter and smaller galaxies lead to the rapid growth of the galaxy's mass.

Formation of a GalaxySimulations from The Center for Cosmological Physics

Welcome to the Universe…