Diffuse Galactic X-ray Diffuse Galactic X-ray Emission & the Galactic Emission & the Galactic
CentreCentre
Bob WarwickUniversity of Leicester
Accreting Black-holes in the Nearby Accreting Black-holes in the Nearby Galaxy M101Galaxy M101
OPTICAL X-RAY
A Normal Face-on Galaxy – M101A Normal Face-on Galaxy – M101
XMM-Newton source-removed EPIC image XMM-Newton source-removed EPIC image with GALEX UV contours superimposed with GALEX UV contours superimposed
(Warwick et al. 2005 in prep.)(Warwick et al. 2005 in prep.)
0.3-1.0 keV0.3-1.0 keV
• Identified phases of the Galactic ISM:
• Very hot: log T > 7.5 i.e. KT > 3 keV.
• Hot: 6 < log T < 7.5, i.e. 0.1 < kT < 3 keV
• Coronal: 5 < log T < 6
• Warm: log T ~ 4, e.g. WIM, WNM.
• Cold: log T 1 - 3 e.g. Molecular clouds
Why are X-rays Important?Why are X-rays Important?
X-ray Emission from the Milky WayX-ray Emission from the Milky Way
Type of Emitter Number in Summed LxType of Emitter Number in Summed Lx Galaxy Galaxy 10 10 38 38 erg serg s-1-1
HMXRB HMXRB 30 ~3 30 ~3LMXRB 100 ~30 LMXRB 100 ~30 SNR ~500 <1 SNR ~500 <1 Low Lx Be Binaries ~10Low Lx Be Binaries ~1044 <1 <1CVs ~10CVs ~105 5 <1 <1 RSCVnRSCVn ~10 ~106 6 <1 <1 Late Type Stars 10Late Type Stars 1010 10 <1<1
Active Nucleus 1 <0.001Active Nucleus 1 <0.001
Diffuse Disk/GCDiffuse Disk/GC 1 1 ~3 ~3Diffuse BulgeDiffuse Bulge 1 ~20 1 ~20Diffuse Halo/Corona 1 ~10Diffuse Halo/Corona 1 ~10
Total ~60Total ~60
Snowden et al. 1997Snowden et al. 1997 Haslam et al. 1982Haslam et al. 1982
408 MHz408 MHz
Chandra Mosaic of the Galactic Chandra Mosaic of the Galactic Centre RegionCentre Region
Wang, Gotthelf & Lang (2002)Wang, Gotthelf & Lang (2002)
X-ray Astronomy Group
The Local Bubble, the Galactic Halo & BeyondThe Local Bubble, the Galactic Halo & Beyond
Loop 1 & the Galactic Bulge EmissionLoop 1 & the Galactic Bulge Emission
The Origin of the Hard Galactic RidgeThe Origin of the Hard Galactic Ridge
Hot Plasma in the Galactic Center RegionHot Plasma in the Galactic Center Region
Fluorescent X-rays from GC Molecular CloudsFluorescent X-rays from GC Molecular Clouds
Topics Topics
X-ray Astronomy Group
The Local Bubble, the Galactic Halo & BeyondThe Local Bubble, the Galactic Halo & Beyond
Loop 1 & the Galactic Bulge EmissionLoop 1 & the Galactic Bulge Emission
The Origin of the Hard Galactic RidgeThe Origin of the Hard Galactic Ridge
Hot Plasma in the Galactic Center RegionHot Plasma in the Galactic Center Region
Fluorescent X-rays from GC Molecular CloudsFluorescent X-rays from GC Molecular Clouds
Topics Topics
Distribution of ~ 10Distribution of ~ 1066 K Plasma in the Local Galaxy K Plasma in the Local Galaxy
Snowden Snowden (2002)(2002)
Galactic Galactic CentreCentre
Galactic Galactic Anti-Anti-CentreCentre
T = 10T = 106.56.5 K K
T = 10T = 106.16.1 K K
GALACTIC PLANEGALACTIC PLANE
Burrows & Mendenhall 1991; Snowden et al. 1991Burrows & Mendenhall 1991; Snowden et al. 1991
IRAS 100 micronIRAS 100 micron RAS ¼ keVRAS ¼ keV
Shadowing of the ¼ keV SXRB in DracoShadowing of the ¼ keV SXRB in Draco
Distribution of ~ 10Distribution of ~ 1066 K Plasma in the Local Galaxy K Plasma in the Local Galaxy
Snowden Snowden (2002)(2002)
270270oo
T = 10T = 106.56.5 K K
T = 10T = 106.16.1 K K
9090oo
Draco Draco NebulaNebula
Cygnus Super BubbleCygnus Super Bubble
Simulated Spectrum of the Galactic Foreground at High LatitudeSimulated Spectrum of the Galactic Foreground at High Latitude
Fang et al, 2005Fang et al, 2005
Local Hot BubbleLocal Hot Bubble
Active GalaxiesActive Galaxies
Galactic HaloGalactic Halo
IGM of Local Group ?IGM of Local Group ?
WHIM ?WHIM ?
Nicastro et al. (2005)Nicastro et al. (2005)
WHIM Absorption Along the Line of Sight to Markarian 421WHIM Absorption Along the Line of Sight to Markarian 421
Fang et al, 2005Fang et al, 2005
Hot gas in a Galaxy GroupHot gas in a Galaxy Group
Void in the WHIM structureVoid in the WHIM structure
Diffuse emission from a WHIM filamentDiffuse emission from a WHIM filament
XMM-Newton EPIC Instrument
Large Effective Area: ~ 2000 cm2 @ 1 keV
Good Imaging Capability: PSF(FWHM) 6 arcsec
Wide Field of View: ~30 arcmin diameter
Broad Bandpass: 0.3-12 keV
Good Spectral Resolution: 120 eV @ 6 keV
X-ray Astronomy Group
XMM MIRRORS
XMM EPIC CCD CAMERAS
pn CCD MOS CCDs
Measuring the Spectrum of the Diffuse XRB with the Measuring the Spectrum of the Diffuse XRB with the EPIC CCDsEPIC CCDs
Particle Particle continuumcontinuum
Instrumental Instrumental fluorescent linesfluorescent lines
Energy (keV)Energy (keV)
pnpn
MOSMOS
Simulated SpectraSimulated Spectra
WHIM FILAMENTWHIM FILAMENT
X-ray Astronomy Group
The Local Bubble, the Galactic Halo & BeyondThe Local Bubble, the Galactic Halo & Beyond
Loop 1 & the Galactic Bulge EmissionLoop 1 & the Galactic Bulge Emission
The Origin of the Hard Galactic RidgeThe Origin of the Hard Galactic Ridge
Hot Plasma in the Galactic Center RegionHot Plasma in the Galactic Center Region
Fluorescent X-rays from GC Molecular CloudsFluorescent X-rays from GC Molecular Clouds
Topics Topics
Distribution of ~10Distribution of ~1066 K Plasma in the Local ISM K Plasma in the Local ISM
Snowden Snowden (2002)(2002)
Galactic Galactic CentreCentre
Galactic Anti-Galactic Anti-CentreCentre
T = 10T = 106.16.1 K K
T = 10T = 106.66.6 K K
ROSAT ALL-SKY SURVEY - ¾ keV IMAGEROSAT ALL-SKY SURVEY - ¾ keV IMAGE
Soft X-ray Spectra of the North Polar SpurSoft X-ray Spectra of the North Polar Spur
Willingale et al. (2003)Willingale et al. (2003)
Willingale et al. (2003)Willingale et al. (2003)
ROSAT ALL-SKY SURVEY - ¾ keV IMAGEROSAT ALL-SKY SURVEY - ¾ keV IMAGE
Ophiuchus Dark Ophiuchus Dark CloudCloud
X-ray Shadowing in the Ophiuchus Molecular Cloud X-ray Shadowing in the Ophiuchus Molecular Cloud
0.2 Energy (keV) 1 2 0.2 Energy (keV) 1 2
EPIC PN SPECTRUM: EPIC PN SPECTRUM: ON/OFF CLOUD ON/OFF CLOUD
Mendes et al. (2005) reported in Breitschwerdt et al. (2005)Mendes et al. (2005) reported in Breitschwerdt et al. (2005)
Image: X-ray 0.5-0.9 keVImage: X-ray 0.5-0.9 keV
Contours: IRAS 100 micronContours: IRAS 100 micron
ROSAT ALL-SKY SURVEY - ¾ keV IMAGEROSAT ALL-SKY SURVEY - ¾ keV IMAGE
EPIC MOS SPECTRA FOR THE GALACTIC BULGE REGIONEPIC MOS SPECTRA FOR THE GALACTIC BULGE REGION
0.0,0.00.0,0.0
345,+24345,+24345,+12345,+12
0.0,-11.90.0,-11.90.5,-8.00.5,-8.0
0.4,-5.40.4,-5.41.1,-3.81.1,-3.8
0.5,-2.60.5,-2.6
X-ray Astronomy Group
The Local Bubble, the Galactic Halo & BeyondThe Local Bubble, the Galactic Halo & Beyond
Loop 1 & the Galactic Bulge EmissionLoop 1 & the Galactic Bulge Emission
The Origin of the Hard Galactic RidgeThe Origin of the Hard Galactic Ridge
Hot Plasma in the Galactic Center RegionHot Plasma in the Galactic Center Region
Fluorescent X-rays from GC Molecular CloudsFluorescent X-rays from GC Molecular Clouds
Topics Topics
The Galactic X-ray RidgeThe Galactic X-ray Ridge
Narrow ridge evident in EXOSAT Galactic Plane Scan Narrow ridge evident in EXOSAT Galactic Plane Scan (Warwick et al. 1985)(Warwick et al. 1985)
Extensively studied in Ginga Extensively studied in Ginga & ASCA Surveys& ASCA Surveys (Yamauchi & Koyama 1993; (Yamauchi & Koyama 1993; Sugizaki et al. 2001)Sugizaki et al. 2001)
6. 7 keV line
Excellent Tracer Galactic Center
Identified as a significant Galactic feature by HEAO1 Identified as a significant Galactic feature by HEAO1 (Worrall et al. 1982)(Worrall et al. 1982)
Spectrum of the Galactic Ridge Spectrum of the Galactic Ridge Emission lines from highly ionized Si, Emission lines from highly ionized Si,
S, and Fe S, and Fe multi-temperature multi-temperature plasma models plasma models
Cosmic X-ray BackgroundCool
componentkT ~0.8 keV
Kaneda et al. (1997)Kaneda et al. (1997)
ASCA GIS 6.7 keV iron line6.7 keV iron line
kT ~ 10 keVkT ~ 10 keV
ORIGIN OF THE HARD COMPONENT?ORIGIN OF THE HARD COMPONENT?
Luminosity of 1.4 x 10^38 erg/sLuminosity of 1.4 x 10^38 erg/s
Energy Density ~10 eV/cm^3Energy Density ~10 eV/cm^3
Too hot to originate in SN activityToo hot to originate in SN activity
Unbound to Galactic DiskUnbound to Galactic Disk
Possible approaches to various aspects Possible approaches to various aspects of the problem:of the problem:
Magnetic reconnection & confinementMagnetic reconnection & confinement
Quasi-thermal plasmaQuasi-thermal plasma
LECRe – non-thermal contributionLECRe – non-thermal contribution
LECR ions & charge exchange LECR ions & charge exchange
See Tanaka (2002)See Tanaka (2002)
Ebisawa et al Ebisawa et al (2005)(2005)
Point source contributionPoint source contribution
Is the Hard X-ray Galactic Ridge due to Is the Hard X-ray Galactic Ridge due to – Truly diffuse emission?Truly diffuse emission?– The superposition of point sources?The superposition of point sources?
Is the Hard X-ray Galactic Ridge due to Is the Hard X-ray Galactic Ridge due to – Truly diffuse emission?Truly diffuse emission?– The superposition of point sources?The superposition of point sources?
Ebisawa et al. (2003,2005Ebisawa et al. (2003,2005))
XGPS-I Survey after Point Source RemovalXGPS-I Survey after Point Source Removal
0.4-1.4 keV0.4-1.4 keV
2-6 keV2-6 keV
XGPS-I Survey after Point Source RemovalXGPS-I Survey after Point Source Removal
2-6 keV2-6 keV
Radio 20 cmRadio 20 cm
G20.7-0.1G20.7-0.1G19.6-0.2G19.6-0.2G20.0-0.2G20.0-0.2
G21.8-0.2=Kes 69G21.8-0.2=Kes 69
Variation of the 2-6 keV surface brightness of Variation of the 2-6 keV surface brightness of the Galactic X-ray Ridge with (l,b)the Galactic X-ray Ridge with (l,b)
-0.5-0.5oo 0.00.0oo +0.5+0.5oo
Galactic LatitudeGalactic Latitude
Galactic LongitudeGalactic Longitude25.025.0oo 5.05.0oo
The 6.7 keV iron line – the key diagnostic?The 6.7 keV iron line – the key diagnostic?
ASCA GIS: 6.61+/-0.02 keV (Kaneda et al. 1997) ASCA GIS: 6.61+/-0.02 keV (Kaneda et al. 1997) nei plasma or a blend of thermal emission with 6.4 keV nei plasma or a blend of thermal emission with 6.4 keV iron fluorescence from LECRe excitation of cold gasiron fluorescence from LECRe excitation of cold gas
ASCA SIS: Blend of 6.70 keV (He-like) & 6.96 keV (H-like) ASCA SIS: Blend of 6.70 keV (He-like) & 6.96 keV (H-like) lines (Tanaka 2002) lines (Tanaka 2002) ~ collisional equilibrium thermal plasma at ~ 8 keV ~ collisional equilibrium thermal plasma at ~ 8 keV very similar spectrum to that seen in Galactic Centre! very similar spectrum to that seen in Galactic Centre!
Chandra: 6.52 +0.08/-0.14 keV (Ebisawa et al. 2005)Chandra: 6.52 +0.08/-0.14 keV (Ebisawa et al. 2005) consistent with ASCA GIS result! consistent with ASCA GIS result!
The X-ray Spectrum of the Galactic X-ray Ridge The X-ray Spectrum of the Galactic X-ray Ridge measured by XMM-Newtonmeasured by XMM-Newton
Raw Raw
BackgroundBackground
Background-subtractedBackground-subtracted 6.7 keV iron line6.7 keV iron line
Equivalent width of 6.4 Equivalent width of 6.4 keV Fe fluorescence keV Fe fluorescence
line < 50 eVline < 50 eV
Preliminary OnlyPreliminary Only
X-ray Astronomy Group
The Local Bubble, the Galactic Halo & BeyondThe Local Bubble, the Galactic Halo & Beyond
Loop 1 & the Galactic Bulge EmissionLoop 1 & the Galactic Bulge Emission
The Origin of the Hard Galactic RidgeThe Origin of the Hard Galactic Ridge
Hot Plasma in the Galactic Center RegionHot Plasma in the Galactic Center Region
Fluorescent X-rays from GC Molecular CloudsFluorescent X-rays from GC Molecular Clouds
Topics Topics
WIDE-FIELD SURVEYAnne Decourchelle SaclayBob Warwick LeicesterMasaaki Sakano LeicesterPeter Predehl MPEDelphine Porquet MPE
SGR A* MONITORINGAndrea Goldwurm Saclayet al
XMM-NEWTON GALACTIC CENTRE SURVEYS
~ 250 ks ~ 400 ks
Sgr A - Radio Arc Region 0.5-1.4 keV X-ray
0.0o
-0.2o
0.2o
0.0o
Galactic Longitude
Gal
actic
Lat
itude
-0.2o
Sgr A*Sgr A*
1E 1743.1-28431E 1743.1-2843
Sgr A - Radio Arc Region 2-4.5 keV X-ray
0.0o
-0.2o
0.2o
0.0o
Galactic Longitude
Gal
actic
Lat
itude
-0.2o
1E 1743.1-28431E 1743.1-2843
Sgr A*Sgr A*Arches Arches ClusterCluster
Sgr A East SNRSgr A East SNR
Sgr A - Radio Arc Region 4.5-6 keV X-ray
0.0o
-0.2o
0.2o
0.0o
Galactic Longitude
Gal
actic
Lat
itude
-0.2o
1E 1743.1-28431E 1743.1-2843
Sgr A*Sgr A*
Arches Arches ClusterCluster
NT X-ray NT X-ray ThreadsThreads
Sgr A East SNRSgr A East SNR
Sgr A - Radio Arc Region 6-9 keV X-ray
0.0o
-0.2o
0.2o
0.0o
Galactic Longitude
Gal
actic
Lat
itude
-0.2o
G0.13-0.13G0.13-0.13
Sgr A*Sgr A*
NT X-ray NT X-ray ThreadsThreads
Transient
Transient
Transient
2-6 keV band
6.4 keV Fe line
2.4 keV S line
6.7 keV Fe line
Spectral Extraction Region
4.5- 6 keV Continuum
Celestial CoordinatesCelestial Coordinates
X-ray Spectrum from the Annular Region around Sgr A
1-3 keV Thermal
7-10 keV Thermal and/or
Non-Thermal
Si XIII S XV
Ca XIXAr XVII
Fe
Al & Si Fluorescence Lines
Fe-line Spectrum from the Annular Region around Sgr A
Fe NeutralFe XXV
Fe XXVI
6.4 keV 6.70 keV 6.96 keV
Intrinsic width of Fe 6.7 keV line 27 +/- 13 eV
S XV
Fe XXV
Fe K
1 keV 1 keV thermalthermal
8 keV 8 keV thermalthermal
Non-thermal bremmstrahlung Non-thermal bremmstrahlung plus 6.4 keV iron fluorescence plus 6.4 keV iron fluorescence from LECRe + molecular gasfrom LECRe + molecular gas
4.5-6 keV Continuum 6.4 keV Iron Line
6.7 keV Iron Line 2.4 keV Sulphur Line
a x
b x c x
a = 1.8 (Z~3 ; LECRe component)
b = 0.75 (Z ~1 ; 1 keV plasma)
c = 3.7 (Z=1 ; 8 keV plasma)
Distribution of 6.7 keV line as a tracer of the Distribution of 6.7 keV line as a tracer of the hard “thermal” componenthard “thermal” component
Corrected for 6.7 keV line Corrected for 6.7 keV line emission originating in the emission originating in the softer ~ 1 keV plasmasofter ~ 1 keV plasma
Surface brightness versus radiusSurface brightness versus radius
Emissivity ~ r Emissivity ~ r -1.3-1.3
6’ = 15 pc
Chandra smoothed, point-source removed 2 - 4.7 keV image.
G
alactic plane
Apparentlythermal outflowfrom SgrA*
Credit: Mark MorrisCredit: Mark Morris
The GC Bipolar Lobes
observed by Chandra
Ratio: soft (2– 4.7 keV) / hard (4.7 – 8 keV) emission(most point sources removed)
6’ = 15 pc
+b
Locations of point sources (Muno et al.)
Hot Diffuse Gas in the Galactic CentreTwo temperature components: 0.8-1.2 keV attributable to supernovae & the GC outflow ~8.0 keV implied energy if diffuse and unbounded ~1040 erg s-1
(Muno et al. 2004)
Latter due to sources? A population A population of 2 x 10^5 CV-of 2 x 10^5 CV-like sources like sources with Lx ~ with Lx ~ 10^31 erg/s at 10^31 erg/s at the Galactic the Galactic Centre would Centre would do the trick!do the trick!
Then how about Then how about trying the same trying the same trick for the trick for the Galactic Ridge!Galactic Ridge!
X-ray Astronomy Group
The Local Bubble, the Galactic Halo & BeyondThe Local Bubble, the Galactic Halo & Beyond
Loop 1 & the Galactic Bulge EmissionLoop 1 & the Galactic Bulge Emission
The Origin of the Hard Galactic RidgeThe Origin of the Hard Galactic Ridge
Hot Plasma in the Galactic Center RegionHot Plasma in the Galactic Center Region
Fluorescent X-rays from GC Molecular CloudsFluorescent X-rays from GC Molecular Clouds
Topics Topics
ASCA
Sgr C
Koyama et al. (1996)
Fe K - Neutral Gas
An X-ray echo of the past activity of Sgr A* ?X-ray echo of the past activity of Sgr A* ?
Churazov, Gilfanov & Sunyaev 1999
Fluorescence of giant molecular clouds illuminated by a flare on Sgr A* producing LX~1039 erg/s, for t > ~10 yrs, ~300 yrs ago.
(Sunyaev et al. 1993, Koyama et al. 1996, Murakami et al. 2001, Revnivtsev et al.2004...)
X-RAY REFLECTION NEBULAE
X-ray Reflection From Cold Near-Neutral MatterX-ray Reflection From Cold Near-Neutral Matter
X-rays
6.4 keV line
Reflection models predict:
Neutral Fe Kalpha Line Eq. Width ~ 150 eV (wrt direct continuum)
Neutral Fe Kalpha Line Eq. Width > 1 keV (Z = 1) (wrt reflected continuum)
Significant iron-K edge on reflected continuum, NFe ~ 2 x 1019 Fe cm-3
dense neutral clouds
Fe K line
•Cosmic-ray electrons E ~ 10 keV – 1 GeV have significant cross-section for interaction with K-shell electrons (Valinia et al. 2000; Yusef-Zadeh et al. 2002)•Such cosmic rays maybe produced in young, massive stellar clusters (Yusef-Zadeh 2003)•Radio data establish a large population of GeV electrons in the inner 300 pc.
Alternative Model: Excitation by Cosmic-ray ElectronsAlternative Model: Excitation by Cosmic-ray Electrons
Fe
Models predict:
Neutral Fe Kalpha Line Eq. Width ~0.55-0.85 keV (Z = 1)
Significantly smaller iron-K edge on non-thermal bremsstrahlung cont.
Tatischeff 2005
6.4 keV line
Chandra Observations – Murakami et al. (2001)
F line = 5.6 x 10-5 photon/cm2/s
E.W. = 2.2 keV
NFe = 3.4 x 1019 Fe cm-2
Sgr B2 Giant Molecular Cloud
Sgr A - Radio Arc Region
0.0o
-0.2o
0.2o
0.0o
Galactic Longitude
Gal
actic
Lat
itude
-0.2o
Radio 20 & 90 cm
6.4 keV Fe fluorescence
line
90 cm
Sgr A - Radio Arc Region
6.4 keV Fe line
0.0o
-0.2o
0.2o
0.0o
Galactic Longitude
Gal
actic
Lat
itude
-0.2o
CS (J=1-0) 10-40 km/s
6.4 keV Fe fluorescence
line
4.5-6 keV Continuum
6.4 keV Fe Line
Correlation of the 4.5-6 keV X-ray continuum and the 6.4 keV line flux
thermal non-thermal
S = -0.3 (not constrained)
NH = 1.7 x 1023 H cm-3
Z = 2.9
X-ray Spectrum of G0.13-0.13 Cloud
Power-Law + Gaussian Line Model:
Photon Index ~ 1.9
NH = 2.3 x 1023 H cm-2
Fline = 2.4 x 10-5 photon/cm2/s
E.W. = 1.45 keV
NFe < 1 x 1019 Fe cm-2
pn
MOS 1/2
Correspondence of X-ray 6.4 keV line with Molecular Gas Correspondence of X-ray 6.4 keV line with Molecular Gas measured in SiO J = 1-0measured in SiO J = 1-0
6.4 keV line6.4 keV line
Handa et al. (2005)Handa et al. (2005)
35-40 km/s35-40 km/s 40-45 km/s40-45 km/s 45-50 km/s45-50 km/s
25-30 km/s25-30 km/s 30-35 km/s30-35 km/s20-25 km/s20-25 km/s15-20 km/s15-20 km/s
Distribution of 6.4 keV Iron Fluorescence near the Galactic Centre
90 light years
Arches Cluster
CS J = 2 –1
20 – 40 km/s
Arches Cluster
Iron 6.7 keV line (black)
Iron 6.4 keV line (blue)
2-6 keV
+0.1o
0.0o
Some Interesting Unresolved Questions Some Interesting Unresolved Questions Relating to Diffuse Galactic X-ray EmissionRelating to Diffuse Galactic X-ray Emission
• What is the origin of the Galactic X-ray halo and does the emission extend into the IGM of the Local Group and beyond?
• Can we determine the X-ray properties and nature of the extended Galactic Bulge against the confusion of LOOP 1?
• What is the origin of the Galactic X-ray Ridge?
• Is the bright central concentration of hard “thermal” emission seen at the Galactic Centre really due to a diffuse component?
• Is the iron-line fluorescence seen throughout the Galactic Centre Region excited by photon illumination or cosmic ray electrons?