Early Disk-Galaxy Formation
From JWST to the Milky Way

TING Yuan Sen  丁源森 

Australian National University

@TingAstro

James Webb Space Telescope

A brief history of the Universe

The Big Bang

Time

Space

Atoms formed

Plasma

Credit: NAOJ, Wayne Hu

Cosmic Microwave Background

COBE 1992

WMAP 2003

Planck 2013

Credit: ESA

A brief history of the Universe

The Big Bang

First stars formed

Make atoms back to plasma ("reionisation")

Credit: NAOJ, Wayne Hu

Credit: ESO

Cosmic reionisation

South Africa and Australia's Square Kilometer Array

A brief history of the Universe

The Big Bang

First galaxies
("city of stars") 

Credit: NAOJ, Wayne Hu

Galaxies evolve

A brief history of the Universe

The Big Bang

First galaxies
("city of stars") 

Milky Way today

Planetary systems

Credit: NAOJ, Wayne Hu

Connecting the Near and the Far

The Near = the Milky Way:  the archetype of (spiral) galaxies

Connecting the near and the far 

The Big Bang

Galactic Archaeology

(Understanding the evolution of the Milky Way)

Credit: NAOJ, Wayne Hu

Tracing the motion of a billion stars in the Milky Way

GAIA Satellite

Credit: ESA

Connecting the near and the far

The Big Bang

Early galaxy evolution

Credit: NAOJ, Wayne Hu

Cosmic redshift 

Credit: NASA/JPL -Caltech/R. Hurt

Cosmic redshift 

Credit: NASA/JPL -Caltech/R. Hurt

Cosmic redshift : redder galaxies = more ancient galaxies

Credit: NASA/JPL -Caltech/R. Hurt

Connecting the near and the far

The Big Bang

Early galaxy evolution

Optical / UV

Infrared

Credit: NAOJ, Wayne Hu

The Earth atmosphere prohibits us the search of old galaxies

Optical

UV

Infra-red (IR)

Credit: NASA / IPAC

Ground-based telescopes

Space satellites

Hubble Space Telescope

2.4m

6.5-10m

Light collecting power = area of the mirror

= \left(\frac{10}{2.4} \right)^2 \simeq 17

Ground base telescope is >10 times faster

6.5m !

James Webb Space Telescope

Where is Wally ?

Time Since Big Bang [ billion years ]

0.3

0.4

0.5

0.6

1

Hubble Space
Telescope

But are they real though ?

James Webb discoveries are in tension with reionisation

The Big Bang

First stars formed

Make atoms back to plasma ("reionisation")

Credit: NAOJ, Wayne Hu

Do we understanding galaxy evolution ? Or reionisation ?

Yes, it appears -- as of 2023!

Other advantages of James Webbs : Resolution !

James Webbs

Old Spitzer Space Telescope

Other advantages of James Webbs : Resolution !

From the ground

James Webbs

Credit: Matthias Steinmetz

Other advantages of James Webbs : Resolution !

James Webbs

Old Spitzer Space Telescope

Other advantages of James Webbs : Resolution !

Credit: NASA / JPL, PHANGS

Shortcomings of James Webb - small field of view

Roman Space Telescope
(2027-)

Credit: Karl Glazebrook

Single Snapshot

Roman Space Telescope (2027- )

Credit: Space Telescope Science Institute