xmm-newton observations of nearby edge-on starburst galaxies

XMM-Newton

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Matthias Ehle - RSSD

XMM-Newton Observations of nearby XMM-Newton Observations of nearby edge-on Starburst Galaxiesedge-on Starburst Galaxies

Matthias Ehle

XMM-Newton Science Operations CentreVilSpa, Spain

European Space Agency (ESA),Research and Scientific Support Department,Science Operations and Data Systems Division

major input from: Michael Dahlem (ATNF), Elena Jimenez Bailon & Maria Santos Lleo (ESA, XMM-Newton SOC)

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The Search for Galactic HalosThe Search for Galactic Halos

To investigate different phases of complex halo ISM, we are conducting multi-wavelength observations

Other members of the gang:

• A.M. Read (Uni Leicester), T.J. Ponman (Uni. Birmingham),

• J.M. Mas Hesse (CSIC-INTA),

• M. Guainazzi (ESA, XMM-Newton),

• T. Heckman, D.K. Strickland (Johns Hopkins Uni.),

• K. Weaver (NASA/GSFC)

• R.F. Haynes (ATNF, Uni. Tas.), J.S. Lazendic (ATNF,CfA),

• S. Ryder (AAO),

• D. Breitschwerdt (MPE),

• U. Lisenfeld (Inst. Astrof. Andalucia)

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The Search for Galactic HalosThe Search for Galactic Halos

Main Goals:Main Goals:

• galaxy sample of sufficient size to study dependence of (multi-wavelengths) halo properties on…

– total SFR, – SFR per unit surface area, energy input rate: Ė / ASF proportional LFIR / ASF – interaction partners, nuclear activity– galaxy’s size, i.e. shape of its gravitational potential

• interdependence of different components of halo ISM?

• investigate metallicity of hot halo gas (X-ray spectroscopy)– chemical evolution of a galaxy– potential impact on enrichment of IGM

• now let’s go and visit the X-ray zoo... – NGC 1511, NGC 1808, NGC 4666, NGC 3628

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NGC 1511: The quest for hot gas in the haloNGC 1511: The quest for hot gas in the halo(Dahlem et al., A&A 403, 547 (2003))

X-ray imagery: XMM-Newton, ~ 30 ks EPIC pn+MOS

soft: 0.5-1.3 keVsoft: 0.5-1.3 keV hard: 2.0-7.5 keVhard: 2.0-7.5 keV

background source?

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NGC 1511: The quest for hot gas in the haloNGC 1511: The quest for hot gas in the haloX-ray spectroscopy with XMM-Newton: (bright source excluded)

• simple models do not fit: complex emission composition• best fit: (others are possible)phabsmekal+phabs(mekal+powl) 0.19 keV (12 % of total flux) 0.59 keV (11 %) photon index 1.4 (77 %) LX(0.2-12 keV) = 1.111040 erg s-1

log(LFIR/LX) = 3.62 typical for starburst galaxies LX,diffuse = 2.551039 erg s-1

log(LFIR/LX,diffuse) = 4.25 relatively low amount of diffuse emission (see Read & Ponman 2001)

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NGC 1511: The quest for hot gas in the haloNGC 1511: The quest for hot gas in the haloXMM-Newton’s Optical monitor:

• 2” FWHM; 17’x17’ FOV; V, B, U, and 3 UV filters (160-600 nm), two Grisms (V, UV, 0.5-1 nm resolution)

UVM2 (centred at 230 nm) UVM2 plus EPIC 0.5-1.3 keVUVM2 (centred at 230 nm) UVM2 plus EPIC 0.5-1.3 keV

absorption due to dust lane

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NGC 1511: The quest for hot gas in the haloNGC 1511: The quest for hot gas in the haloComparison with radio continuum data: (Dahlem et al. 2001)

ATCA: 13 cmATCA: 13 cm

EPIC 0.5-1.3 keVEPIC 0.5-1.3 keV

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NGC 1511: The quest for hot gas in the haloNGC 1511: The quest for hot gas in the halo

Summary:Summary:

• XMM-Newton observations reveal presence of previously unknown extended hot gas, partly extending out of disk plane, extra-planar emission also seen in radio continuum

• emission distribution is asymmetric: bright in eastern half, where also radio continuum suggests highest level of star formation

• spectral analysis shows complex emission composition

• X-ray properties characterise NGC 1511 as starburst galaxy

• UV, H, NIR suggest that NGC 1511 is heavily disturbed (by two small companions?) not an ideal candidate to test halo properties dependence on star formation in underlying disk...

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NGC 1808: Combined starburst/AGN activityNGC 1808: Combined starburst/AGN activity

High star-forming activity:High star-forming activity:• HII regions in 1 kpc circumnuclear region (Forbes `92)

AgeSFR ~ 8-17 Myr (Kotilainen`96)

• SNR population detected in IR and radio (Saikia `90)

• starburst activity (and peculiar morphology) due to a recent interaction with NGC 1792 (Dahlem `90; Koribalski `93)

Nuclear activity: starburst and/or AGN?Nuclear activity: starburst and/or AGN?• Analysis of optical emission lines (Kotilainen `96) and polarised light (Scarrott `93) point out

presence of Seyfert 2 nucleus together with intense SF activity

• ISO: only 10% of nuclear emission is due to stellar activity (Siebenmorgen 2001)

• ROSAT data (Dahlem `94; Junkes `95) and ASCA (Awaki `96) can be explained assuming a hot plasma and/or SNR; other possibilities can not be ruled out

• Ginga observations (Awaki `93) suggest NGC 1808 has obscure nucleus

• Nuclear emission remains unclear but shows high contributions of star forming activity

(Jimenez Bailon et al., astro-ph/0301109; A&A, in prep.)

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NGC 1808: Spatial analysis of X-ray emissionNGC 1808: Spatial analysis of X-ray emission

Peak position:Peak position:

• X-ray (XMM-Newton, Chandra (Zezas et al.), UV (XMM-Newton) and R-optical images are consistent: location of maximun luminosity corresponds to an unresolved point-like source

HH X-ray: EPIC, 36 ksX-ray: EPIC, 36 ks X-ray: ChandraX-ray: Chandra X-ray: pnX-ray: pn

UVW1 UVW1

UVW2UVW2

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NGC 1808: Spatial analysis of X-ray emissionNGC 1808: Spatial analysis of X-ray emissionEnergy bands (pn):Energy bands (pn):• non-nuclear sources detected at lower energies

• nucleus visible in all energy range

• 0.5-2 keV soft band: emission associated with star-formation activity

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= 0.86 ± 0.07NH,mekal= 2.1+0.5

-0.21021 cm-2

kT = 0.57+0.02-0.05 keV

[Ne] = 1.5+0.9-0.6

[Mg] = 2.0+0.9-0.6

[Si] = 1.6+0.9-0.6

[Fe] = 0.6+0.2-0.1

NGC 1808: Spectral analysis of EPIC-pn dataNGC 1808: Spectral analysis of EPIC-pn data

bulk of X-ray emission originates from nuclear region:bulk of X-ray emission originates from nuclear region:

EPIC-pn spectrum of central 850 pc: best fit: phabs (zpow + vmekal)

thermal components (which account for the main part of the soft X-ray emission), plus power law required to explain hard energy tail:

L0.24-10keV=1.6 ± 0.31040 erg s-1

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XMM-Newton RGS (0.35-2.5 XMM-Newton RGS (0.35-2.5 keV) spectrum:keV) spectrum:

• no continuum emission larger than noise, but emission lines visible

• emission lines at wavelenghts and with relative ratios similar to strongest features identified in RGS data from prototypical starburst galaxy M82 (Read & Stevens 2002)

• weak lines seen in M82 but not detected in NGC 1808: M82 is brighter so its RGS spectrum has better S/N

soft X-ray spectrum in NGC 1808 is dominated by thermal emission from a starburst

NGC 1808: Spectral analysis of RGS dataNGC 1808: Spectral analysis of RGS data

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NGC 4666: a “Superwind” NGC 4666: a “Superwind” ggalaxyalaxy

• FIR luminosity higher than for actively star-forming galaxies NGC 253 and NGC 4631 high global SFR in NGC 4666

• log (LFIR/LB) = 0.48 & FIR colour f60/f100 = 0.45 NGC 4666 is a typical FIR-selected galaxy (Lehnert & Heckman `95) good candidate for multi wavelength search for halo emission (cf. Dahlem et al. `95)

• First evidence for existence of starburst driven galactic superwind in NGC 4666 given in Dahlem et al. `97:– optical emission line imagery: filaments– optical line diagnostics: shocks as main heating source– radio continuum maps: halo detected– radio polarization data: B-fields follow flow or allow it (?)– X-rays: ROSAT PSPC: soft extended extraplanar emission

(Ehle, Dahlem et al., A&A, in prep.)

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X-ray imaging results: X-ray imaging results: ROSAT versus XMM-NewtonROSAT versus XMM-NewtonROSAT PSPC ROSAT PSPC (Dahlem et al. `98)(Dahlem et al. `98)0.25 keV, 48” FWHM0.25 keV, 48” FWHM

XMM-EPIC, ~55 ksXMM-EPIC, ~55 ks0.2-0.5 keV, smoothed to 10” FWHM0.2-0.5 keV, smoothed to 10” FWHM


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X-ray imaging results: XMM-Newton energy bandsX-ray imaging results: XMM-Newton energy bands

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NGC 4666: a “Superwind” galaxyNGC 4666: a “Superwind” galaxy

Multi-wavelength (qualitative) comparison:Multi-wavelength (qualitative) comparison:

Radio continuum & HRadio continuum & H (Dahlem et al. `97):• clear detection of radio halo (6, 20 cm)• spectral steepening away from disk• outflow cone from central starburst (radial diameter 6.5 kpc), traced by optical

filaments up to 7.5 kpc above disk • polarized radio spurs: outer wall of

outflow cone?• vertical B-fields: pushed out by

superwind, or poloidal dynamo field?

HI observations HI observations (ongoing)XMM-EPIC: 0.5-0.9 keVXMM-EPIC: 0.5-0.9 keV

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NGC 4666: Spectral analysis of EPIC-pn dataNGC 4666: Spectral analysis of EPIC-pn data

diffuse X-ray emission from disk and halo regions diffuse X-ray emission from disk and halo regions (preliminary results):(preliminary results):

best (not perfect!) fit: phabs (mekal + powerl)• halo fit improves with free Z...(~ 0.1 Zsolar), seems unphysical (starburst enriches outflowing material), wrong CIE assumption (see Breitschwerdt `03)• bulk of soft emission due to hot gas:

• mekal contributes 60% (disk), 74% (halo) to soft 0.3-0.9 keV flux

• in disk higher contribution due to powerl: unresolved point-like sources, XRBs

• powerl contributes 87% (disk) and 59% (halo) to total 0.3-12 keV flux

• higher gas temperature in the disk:• 0.29 0.01 keV (disk)• 0.21 0.01 keV (halo)

diskdisk

halohalo

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NGC 4666: a “Superwind” galaxyNGC 4666: a “Superwind” galaxy

Summary:Summary:

• XMM-Newton observations reveal huge, structured hot gas halo, on both sides of disk; southern soft emission absorbed due to inclined disk

• spectral analysis shows complex emission composition: fit with mekal (CIE) model NOT ok: Breitschwerdt (NIE) model needed?

• X-ray properties confirm: superwind exists in NGC 4666

• interesting correlation of X-ray, H, polarization filaments: outflow cone & walls: energy densities to be compared...

• ...

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NGC 3628: outflow & a strangeNGC 3628: outflow & a strange bright bright source source

• NGC 3628 is interacting member of Leo Triplet

• collimated outflow from starburst nucleus detected by Einstein (Fabbiano et al `90) and X-ray halo confirmed by ROSAT (Dahlem et al. `96)

• strange nuclear X-ray source (unresolved with ROSAT): strong variability (faded by factor >27 between 1991 - 1994) variable obscuration of AGN or HXRB (>75 Msol black hole)?

• Chandra (52 ks, Strickland et al. 2001): luminous source visible again, but 20” offset from nucleus

• XMM-Newton (~50 ks): analysis started, some preliminary results...

(Ehle, Read et al., A&A, in prep.)

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NGC 3628: outflow & halo emissionNGC 3628: outflow & halo emission

ROSAT PSPC ROSAT PSPC (Dahlem et al. `96)(Dahlem et al. `96)0.75 keV, 48” FWHM0.75 keV, 48” FWHM

XMM-EPIC XMM-EPIC (plus DSS contours)(plus DSS contours)0.3-0.5, 0.5-0.9, 0.9-2 keV, 10” FWHM0.3-0.5, 0.5-0.9, 0.9-2 keV, 10” FWHMXMM-EPIC XMM-EPIC (plus DSS contours)(plus DSS contours)0.3-0.5, 0.5-0.9, 0.9-2 keV, 10” FWHM0.3-0.5, 0.5-0.9, 0.9-2 keV, 10” FWHM

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NGC 3628: central emissionNGC 3628: central emissionChandra Chandra ((Strickland et al. 2001))0.3-8 keV, 1” FWHM0.3-8 keV, 1” FWHM

XMM-EPICXMM-EPIC 0.3-8 keV slightly smoothed0.3-8 keV slightly smoothed

Preliminary spectral fit to IXO:

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The Search for Galactic Halos: CommentsThe Search for Galactic Halos: Comments• high f60/f100 FIR colour (> 0.4): successful criterion for halo candidates (shown to work for radio

halos, X-ray sample still small)

• galaxies with highest Ė / ASF show most prominent radio halos; TBC for X-ray halos

• Contradiction to Irwin et al. `99 ?: no such connection between radio halo and SF level in disk - BUT: different object classes (Sy-2 nuclei, magellanic irregulars, interacting galaxies, unresolved emission)

• add HI observations (VLA & ATCA, ongoing)

info on inclination angle, intrinsic absorbing gas distribution & kinematics, search for extraplanar HI (tracers of tidal interactions)

• all physically small galaxies (D25 20 kpc), even with f60 / f100 < 0.4, have prominent (radio) halos; low total mass CR electrons (and hot gas?) escape easier from disks

• spatial resolution & sensitivity of XMM-Newton allows detailed comparisons with optical/radio filaments (originating in strongest SF regions); energy budget of different ISM components

• spectral sensitivity allows separation of starburst/AGN & detailed study of hot gas (CIE versus NIE)

• Final goal: to create galaxy sample of sufficient size to study dependence of halo properties on several parameters

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NGC 4666NGC 4666

NGC 4668 NGC 4668 (undet. ROSAT)(undet. ROSAT)

companioncompanion

companioncompanion

NGC 4666: a “Superwind” galaxyNGC 4666: a “Superwind” galaxyHI HI (VLA) map(VLA) map (Walter et al., ApJ subm.) && 0.5-0.9 keV XMM-Newton EPIC 0.5-0.9 keV XMM-Newton EPIC

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NGC 3628: fit to NGC 3628: fit to the the luminous sourceluminous source

Chandra Chandra ((Strickland et al. 2001)) XMM-Newton pnXMM-Newton pn

best fit model: wabs powl NH FX,0.3-8keV FX,0.3-2keV F X,2-8keV

Chandra: 8.0+1.2-1.11021 1.82+0.21

-0.20 9.40 10-13 4.75 10-13 4.65 10-13

XMM-pn: 6.6+0.8-0.61021 1.74+0.10

-0.09 8.49 10-13 4.00 10-13 4.49 10-13

xmm-newton observations of nearby edge-on starburst galaxies

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