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