Molecular Hydrogen in the outer filaments surrounding NGC 1275 Nina Hatch CS Crawford, RM Johnstone, AC Fabian IOA, Cambridge
Dec 31, 2015
Molecular Hydrogen in the outer filaments surrounding
NGC 1275
Nina Hatch
CS Crawford, RM Johnstone,
AC Fabian
IOA, Cambridge
Central Cluster Galaxy Emission-line nebulae• Emission line nebulae are found
surrounding ~27% of CCG
• Bright and extended structureCowie et al
1983
Conselice et al 2001
• Only find emission line nebulae if cluster
has a short radiative cooling time and
bright centrally peaked x-ray emission
Perseus: 200ks Chandra
Fabian et al 03
Unsharped mask of X-ray image of Perseus cluster
Fabian et al, 2003
NGC1275/Perseus cluster in Hα
Conselice et al 2001
Edge et al, 2002
Similar line ratios found in outer filaments as in the nucleus – indicating similar ionising mechanism
Velocity shear across lower filaments ~ 175km/s
Velocity shift relative to nucleus
Ionisation MechanismsExcitation source of optical filaments still uncertain
-short cooling time → gas continually ionised
- Soft X-ray/Hα indicate filaments radiate predominantly in optical → soft x-rays do not ionise
Possible mechanisms
• UV photoionisation from nearby stars
-likely to be dominant mechanism in Eastern knot
• shocks
• conduction from hot ICM Will analyse line ratios using CLOUDY
Summary
• Detection of molecular hydrogen ~ 25kpc from CCG, deeply embedded within hot ICM
• Velocity shift between outer filaments and central nebula and within filaments
• Spectra indicate different ionisation mechanisms acting on filaments