Coronal gas Inverse Compton emission (= sca4ering of photons off - - PowerPoint PPT Presentation

Coronal gas

Inverse Compton emission (= sca4ering of photons off rela8vis8c electrons)

Lab Electron frame Lab

hν ~γhν ~γhν ~γ hν

2

Synchotron radia8on

Non-relativistic case: balancing centrifugal and Lorentz force gives cyclotron frequency

Example: AGN NGC 4051

Red = disc component Green line = synchotron Blue line = inverse Compton

Ionised gas

• The Galaxy seen in Hα

Con8nuum radia8on from ionised gas

Free-free (aka bremsstrahlung = braking radia8on)

Not necessarily X-ray

í See ` High energy Astrophysics’ (Melia) p.91

Bremsstrahlung examples

X-ray bremsstrahlung in cluster of galaxies (Perseus) : T=10^8K Radio bremsstrahlung (green) in star forming region NGC3603 cf

The importance of measuring L_ion

• Measuring star forma8on

rate in external galaxies

0.5 1 1.5 2 35 40 45 50

Log Φ ion Log M_* cf

Feedback from ionising radia8on

Pink = H α emitting bubbles surrounding young stars: note spiral structure

A close-up of ionised bubbles in 30 Doradus

Simula8ons of ionising feedback in realis8cally inhomogeneous clouds

Ionising photons can’t penetrate dense gas which con8nues to form stars. Strong ou[lows driven from low density channels but don’t carry much mass

ç ì

Feedback from ionising radia8on can also promote star forma8on

• The ISM contains many bubbles

blown by winds from individual massive stars

• The effects of mul8ple supernovae

from stars in a cluster can also be modeled as a `superwind’ which creates `superbubbles’ in the ISM

ì

Feedback from winds and supernovae

Are wind driven super-bubbles the key to understanding the structure of the foamy ISM?

Can we understand the dis8rbu8on of holes of different sizes in terms of the distribu8on of clusters of different N?