Hot Gas and Outflows of Nearby Normal Galaxies
Q. Daniel Wang (UMass)
• Most of present galaxies are not nuclear starbursters
• Phenomena that would be otherwise overwhelmed– Disk/halo interaction– Bulge wind driven by Type Ia SNe– Accretion from the IGM
Subtle, but enduring strongly affect the evolution of galaxies
ROSAT all-sky survey (3/4-keV band)
Absorption Sight Lines
No detection X-ray binaryAGN
Yao & Wang 2005
Wang et al. 2005
Ionization fraction
Assuming CIE and solar abundances
OVI
OVIIIOVII
Ne IX
Ne VIII
Ne IX
Also detection of OVII K,
K,and OVIII K linesMean T ~ 106.3+/-0.2 KnH~3.4x10-3 cm-3
(assuming filling factor =1)
Ne IX K absorption lines in LMXB
spectra
Hot gas disk model
nH = 5.0(-1.8,+2.6)x10-3 cm-3exp[-|z|/1.2(-0.5,+0.7) kpc]
Total NH~1.6 x1019 cm-2
X-ray absorption is primarily around the Galactic disk within a few kpc!
MRK 421
Mkn 421 3C 273
LETG/ACIS
LETG/HRC
Differential X-ray absorption line spectroscopy
Depth:
NH =n d
=(3-11) x1019 cm-2
n2 d ~ 2x10-2 cm-6 pc
d ~ 5 kpc
Doppler broadening:
b=31-46 km/s
for Mrk 421
b=120 (80-204) km/s
for 3C 273
Wang & Yao 2005
Summary: Galactic hot gas disk
•Vertical scale ~ 1-3 kpc•Mean temperature ~ 106.2 K•density ~ 3 x 10-3 cm-3
•Metal abundance ~ solar
NGC 3556: optical vs. X-ray
Red – optical
Green – 0.3-1.5 keV band
Blue – 1.5-7 keV band
NGC 3556: radio vs. X-ray
Wang et al. 2003
Sb galaxy NGC 4565
William McLaughlin (ARGO Cooperative Observatory)
Red – optical
Green – 0.3-1.5 keV band
Blue – 1.5-7 keV band
Wang (2004)
Very low specific SFR
No sign for any outflows from the disk in radio and optical
No correlation with radio!
•Lx ~ 3 x 1039 erg/s
NGC 4594: X-ray vs. optical
ACIS-S 0.3-1.5 keV intensity contours
Diffuse 0.3-1.5 keV intensity contours
H ring
NGC 4594:X-ray
spectraPoint source
Inner bulge
Outer bulge
disk
•Average T ~ 6 x 106 K
•Slight softening in the disk and in the outer bulge
•Strong Fe –L complex
•Lx ~ 4 x 1039 erg/s NGC 4631
Missing stellar feedback in early-type disk galaxies
• For NGC 4594, hot gas radiative cooling rate ~ 2% of LSN ~ 2.4 x 1041 ergs/s from Type Ia SNe alone
• Not much cool gas to hide or convert the SN energy
• Mass and metals are also missing!– Mass input rate of evolved stars
~ 1.3 Msun/yr– Each Type Ia SN 0.7 Msun Fe
Gone with the wind!
Bulge wind model
• Spherical, steady, and adiabatic • NFW Dark matter halo + stellar bulge• Energy and mass input follows the
stellar light distribution• CIE plasma emission• Implemented in XSPEC for both
projected spectral and radial surface brightness analyses
Li & Wang 2004
Data vs model
Consistent with the expected total mass loss and SN rates as well as the Fe abundance of ~ 4 x solar!
The best-fit model density and temperature profiles of the bulge
wind
Outflow-inflow interaction
NGC 3379: ram-pressure confined galactic wind?
Conclusion
• At least two components of diffuse hot gas:– Disk – driven by massive star formation– Bulge – heated primarily by Type-Ia SNe
• There is so far little evidence for X-ray emission or absorption from IGM accretion halos. But there are indications from the interaction with other gaseous components.
