x-ray study of a nearby nuclear x-ray study of a nearby nuclear starburst and a nearby agn starburst...
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X-ray study of a nearby nuclear X-ray study of a nearby nuclear starburst and a nearby AGNstarburst and a nearby AGN
Roberto Soria (Roberto Soria (UCL)UCL) Mat Page, Kinwah Wu, Alice Breeveld, Silvia Zane
ContentsContents
M83 (grand-design spiral with nuclear starburst) diffuse emission discrete source populations multi-wavelength comparisons
M81 (grand-design spiral with active nucleus) discrete source populations origin of the X-ray emission lines comparison between Milky Way, M83, M81
For more details, see recent papers by our UCL group(Soria et al 2003, Page et al 2003, 2004)
STAR FORMATION
Stellar evolutionPNe, SNe II, Ib/c
Compact remnantsHMXB, LMXB
Cold gas
Hot gas (shocks)Diffuse soft X-rays
X-rays from accretion
External triggersInternal triggers?
A look in detail: M83 (d M83 (d ~~ 4 Mpc) 4 Mpc)
10 arcsec
Super-soft source
Wind / XRB?
X-ray binary
galactic nucleus
SNR?
ULX
X-ray pulsar
Starburst nucleus
Spiral arms
High abund of Ne, Mg, Si,S Low Fe/O, Fe/C
ISM is enriched bywinds from WR stars, core-collapse SNe
T ~ 0.6 keV
T ~ 0.4 keV
80% of X-ray luminosity is from diffuse hot gas
Diffuse emission from the starburst nuclear region of M83(multi-temperature thermal plasma fit, T ~ 0.3--0.8 keV)
Identification of the X-ray sources: multiwavelength comparisons
Chandra/ACIS HST/WFPC2
HST/WFPC2 greyscale, Chandra contours
H
gre
ysca
le (
SS
O),
Ch
and
ra c
on
tou
rs (
0.3
--8
keV
)
V-b
and
gre
ysca
le (
VLT
), 6
cm
rad
io c
onto
urs
(V
LA)
Cumulative luminosity distribution of the discrete X-ray sources in a galaxy
104010381036N(>L)
L
“normal” spiral population
Starburst/star-forming regions
Ellipticals
erg/s
Breaks in the luminosity distributionLuminosity functions in M83 Luminosity functions in M81
Breaks/features in the luminosity function may depend on:
Eddington limit for the neutron stars distance indicator ageing of the X-ray binary population (Wu 2001)
galactic history indicator
outside diskoutside disk
starburst nucleus
Colour-colour plotfor bright M83 sources
Supersoft sources
Soft sources (SNR +)
X-ray binaries (BH, NS)
Candidate X-ray SNR are associated to brighter HII regions
HH
H
gre
ysca
le (
SS
O),
Ch
and
ra p
oin
t sou
rces
6 c
m r
ad
io g
reys
cale
(V
LA),
Ch
and
ra p
oin
t sou
rces
many SNR in M83, fewer in M81
M81 composite imageM81 composite imageUV (XMM Optical Monitor) + X-rays (XMM EPIC)
M81’s active nucleus: simple power-law fit ( = 1.9)
L (2-10 keV) = 1.5 1040 erg/s
M81’s active nucleus: power-law ( = 1.9) + Fe lines
L (2-10 keV) = 1.5 1040 erg/s
Cold Fe (I-XVI)6.4 keV
Warm Fe (XVII-XXV)6.7 keV
Hot Fe (XXVI)6.96 keV
Three narrow components of the Fe K line
6.4 keV6.4 keVFluorescent emission due to cosmic-ray electrons hitting cold (molecular) gas
Milky WayMilky Way
6.7 + 6.9 keV6.7 + 6.9 keVFrom faint X-ray binaries?
Interaction of non-thermal electrons with hot (0.2-0.5 keV) gas?
6.4 keV6.4 keVFluorescent emission due to cosmic-ray electrons hitting cold (molecular) gas
M81M81
6.7 + 6.9 keV6.7 + 6.9 keVInteraction of non-thermal electrons with hot (0.2-0.5 keV) gas?
X-ray photoionised gas?
From faint X-ray binaries?
M81’s soft X-ray spectrum (XMM RGS)
L (0.3-2 keV) = 1.5 1040 erg/s
O VII emission
resonanceresonance
forbiddenforbidden
Luminosity from hot gas component = 5 1038 erg/s (only 5% of total)
resonanceresonance
forbiddenforbidden
Hot gas temperature = 0.2—0.7 keV
Hot gas is collisionally ionised, NOT photoionised
Ionising source: Type Ia SNe in low-density medium
Summary & work in progressSummary & work in progressX-ray study of a nearby starburst (M83) and AGN (M81)
Relation between star-formation rate and hot gas temperature & density
Diffuse emission probes recent starburst in M83 (107 yrs)Core-collapse SN remnants & high-mass X-ray binaries
Diffuse emission in M81 probes older activity (109 yrs)Type Ia SN remnants & low-mass X-ray binaries
Luminosity and colour distributions of discrete X-ray sources probe galactic star formation history
Three components in 6.4-6.9 keV Fe line emission in M81
Lancon et al, in prep
M82M82