ix reunión de la sea · 2010-09-20 · basic propertiesbasic properties • haro 2/mrk 33 • blue...

IX Reunión de la SEAEvolutionary state of the Lyman Alpha

Emitter Haro 2Emitter Haro 2

Héctor Otí FloranesHéctor Otí FloranesJose Miguel Mas Hesse

Centro de Astrobiología (CSIC-INTA) 17 de septiembre 2010

LINK LOCAL EMITTERS →HIGH-REDSHIFT SOURCES

• Lyα is an intense line observed in the optical in high-z sourcesy p g– Used to quantify Star Formation Intensity– Relevant for Cosmology

H th t i t t i i l L f i th• However, that is not trivial: Lyα escape from source is a rather complex issue due to resonance scattering in neutral hydrogen

• Therefore, it is crucial to understand how Lyα photons are produced, , y p p ,absorbed, scattered and finally escape from the source

• Haro 2 Lbol is similar to LAEs at z=3.1 (Gawiser et al. 2007; Gronwall et al 2007) which are a proxy of the low L end of LBGset al. 2007), which are a proxy of the low-L end of LBGs

• Hence, Haro 2 is the best local prototype of Lyα-emitting galaxies at high z

Héctor Otí IX Reunión de la Sociedad Española de Astronomía 13-17/09/2010 2

BASIC PROPERTIESBASIC PROPERTIES

• Haro 2/Mrk 33• Blue Compact Dwarf Galaxy• Distance = 20.5 Mpc• 1arcsec 100 pc• 1arcsec ∼ 100 pc• Galactic E(B-V) ∼ 0.012• High Z for BCDGs:

12+log(O/H) = -3.5 => Z ∼Zo/2


Lyα EMISSIONLyα EMISSION

• Lequeux et al. (1995)q ( )

P P CygCyg

• Despite being a metal-rich, dusty galaxy, Lyα emission was found• Neutral gas is expanding as a superbubble at ∼ 200 km s-1, which

allows the red wing of the line to escape with a P Cyg profileallows the red wing of the line to escape, with a P Cyg profile


STAR-FORMING KNOTSSTAR-FORMING KNOTS

Knot SE Knot NWCompact source

Age ∼ 4 MyrHST/FOC HST/FOC

imageimage

Knot NWRather extended

sourceM ∼ 7×105 Mo

E(B-V)=0.05050% UV continuum at

Age ∼ 5 MyrM ∼ 1.3×106 Mo

50% UV continuum at Lyα absorbed

E(B-V)=0.02025% UV continuum at

Lyα absorbedLyα absorbed

IMFSalpeter2-120 Mo

Starburst total massM ∼ 2e+6 Mo

Stellar mass of the galaxyM 3e+9 M


M 2e 6 Mo M ∼ 3e+9 Mo

PROPERTIES OF KNOTSPROPERTIES OF KNOTS

SiIVSiIV CIVCIV SiIVSiIV CIVCIV

• There is a temporal shift of ∼1 Myr between both knotsThere is a temporal shift of 1 Myr between both knots• Age was calculated fitting SiIV and CIV UV lines (following the method by R. González-Delgado)

in the normalized spectra with the available Starburst99 UV spectral libraries: Zo and SMC/LMC• Different metal content in knots?

S• Knot SE– UV line spectrum could only be fitted with Zo library

• Knot NW– On the other hand, knot NW could be fitted with both libraries, finding a similar value of ∼5 Myr


g y

Lyα EMISSION: MINOR AXISLyα EMISSION: MINOR AXIS

HST/STISHST/STISspectralspectralimageimage

SWSW

λλ

LyLyαα


Lyα PROFILE: MINOR AXISLyα PROFILE: MINOR AXIS

• Mas-Hesse et al. (2003): Lyα emission not ( ) yspatially coupled to stellar continuum in knot SE

Compact Lyαcomponent ∼ 250 pc

Extended, diffuse Lyαcomponent 350 pc

P-Cygni profile High resolutionspectrum: 0 053 Å


component ∼ 350 pc spectrum: 0.053 Å

Lyα EMISSION: MAJOR AXIS

NWNW

λλ

LyLyαα

HST/STISHST/STISspectralspectralimageimage


Lyα PROFILE: MAJOR AXISLyα PROFILE: MAJOR AXIS

SESENWNW

• Emission profile isEmission profile is rather complex, with several emitting and absorbing regionsabsorbing regions

• Diffuse emission is very extended: > 600 pc



• Different profiles of FUV and NUV continuum

• De-coupling between Lyαp g yemission and continuum

• Absence of continuum in region showing diffuse Lyα emission → Lyα photons escape after multiple scattering?

• In knot NW there is a weak Lyαemission (NW B) within aemission (NW B) within a continuum-dominated region NW ANW A

NW BNW B

SESE



• Hα is produced in the regionsgdominated by the stellarcontinuum → gas ionized by massive stars→ recombinations→ recombinations

• Only NW B Lyα emissioncoincides with Hα emission→ HI is efficiently pushed→ s e c e t y pus ed

outwards allowing the escape of Lyα photons

• NW A: diffuse Lyα emission. Highly scattered or due tocollisional excitation?

• Luminosity of diffuse componentNW A is as high as intensity of

NW ANW A

NW BNW B

SESE

NW A is as high as intensity of compact SE emission


X-RAY IMAGEX-RAY IMAGE

• X-ray emission is confined in aX ray emission is confined in a region of radius ∼600 pc

• Hard X-ray emission is located around the SE knot

• Soft X-ray emission is extended, especially to the NW

• Older burst NW (→ more time the NWsuperbubble to expand) shows

larger diffuse emission NW

SE


X-RAY SPECTRUMX-RAY SPECTRUM

Model: Gal. Abs. * Intr. Abs. * ( Hot plasma + Power Law(fixed Γ) )• Fixed parameters:

– Galactic absorption: N(HI)=6.3×1019 cm-2

– Intrinsic absorption: N(HI)=7.0×1019 cm-2

P l i d Γ 1 0 1 2– Power law index: Γ=1.0 - 1.2

• Values of the free parameters:– Hot plasma temperature: kT=0.73±0.1 keVp p

• Values of the luminosities (D=20.5 Mpc) when integrating over the whole region:

L(0 4 2 4 keV)=2 3×1039 erg s-1– L(0.4-2.4 keV)=2.3×1039 erg s 1

– L(2.0-10.0 keV)=2.3×1039 erg s-1

Soft X-ray emission is consistentSoft X-ray emission is consistentwith predictions by CMHK02 models with εXeff∼1-5%


X-RAY IMAGEX-RAY IMAGE

• Our CMHK02 synthesis evolutionary models predict the LsoftX with εXeff ∼ 1-5%

– Summers et al. (2001) derived ε ∼2% for Haro 2εXeff∼2% for Haro 2

– Typical range for similar sources (Strickland & Stevens 1999; Summers et al. 2001, 2004; Mas-Hesse et al 2008)Hesse et al. 2008)

• On the other hand, LhardX is underestimated by one order ofunderestimated by one order of magnitude. LhardX is associated toa single compact source

– Given the high value of LhardX, the hard source on knot SE may be a ULX (>1e+39 erg s-1)


SOFT X-RAY EMISSIONSOFT X-RAY EMISSION

Diff L i i i• Diffuse Lyα emission is always found in soft X-ray emitting regions

– Same physical origin for both emissions: collisional heating

diffdiffcollisional heating

– Lyα is produced by collisional excitation of H atoms

diffusediffuse

LyLyαα– Collisional nature of Lyα

is supported by the lack of Hα component

yy


CONCLUSIONSCONCLUSIONS• We identify in Haro 2 two starbursting knots

NW 5 M M 1 3 6 M d E(B V) 0 020– NW: 5 Myr, M∼1.3e+6 Mo and E(B-V)=0.020– SE: 4 Myr, M∼7e+5 Mo and E(B-V)=0.050

• Lyα emission along its minor axis– Compact Lyα component ∼ 250 pc– Extended, diffuse Lyα component ∼ 350 pc

• A rather complex spatial profile of Lyα emission along its major axis– A large, strong diffuse emission extending > 600 pc northwest of knot NW– A weak emission within continuum region of knot NW– A strong, compact emission close to knot SEg p

• X-ray data– Fitting: hot plasma (heated gas) and a power law (HMXBs or ULX?)– εXeff ∼ 1-5% → in agreement with previous results in star-forming galaxiesεXeff 1 5% → in agreement with previous results in star forming galaxies

• Diffuse, soft X-ray emission coinciding spatially with the diffuse Lyαradiation → same physical origin for both emissions → diffuse Lyαcomponents are produced through collisional excitationscomponents are produced through collisional excitations


ix reunión de la sea · 2010-09-20 · basic propertiesbasic properties • haro 2/mrk 33 • blue...

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