collisionalionizationandexcitation.ppt

1、Evolution in Lyman-alpha Emitters and Lyman-break Galaxies,Masao MoriTheoretical Astrophysics division,Center for Computational Sciences, University of TsukubaCollaboration withMasayuki UmemuraHidenobu Yajima,Presentation Outline,Three-dimensional Hydrodynamic Model of Bright Lyman Alpha Emitters (L

2、yman Alpha Blobs) Mori & Umemura, Nature, 440, 644 (2006) Evolutionally sequence among bright Lyman alpha emitters, Lyman break galaxies, and elliptical galaxiesApplication to Faint Lyman Alpha Emitters Mori, Yajima & Umemura in prep.Star formation histories of LAEs with different massesDynamical an

3、d chemical evolution of LAEsEmission process of Lyman alpha photons (photo ionization vs collisional ionization),Compact LAE and Extended LAE,Private communication with Hayashino, Mastuda, Yamada et eal.,Extended LAE,Compact LAE,Matsuda et al. 2004,Observational properties,Compact LAEs Extended LAEs

4、Lya luminosity: 1042-43 1042-44 erg s-1 Size (Lya): a few kpc 10-100 kpcMorphology: UV: compact scattered Lya: extended very extendedStellar mass: 108-10 M 1010-11 M SFR: 110 M yr-1 10 100 M yr-1,Part IThree-dimensional Hydrodynamic Model of Bright LAEs,Images of Bright Lyman Alpha Emitters (Lyman a

5、lpha blobs),190 kpc at z = 3.1,Matsuda et al., AJ, 128, 569 (2004) observed the 35 extended Ly emitters in and around the SSA22a field at z=3.09. The luminosity range of Ly emission is 6x1042 to 1044 erg s-1. They have bubble-like features, and filamentary and clumpy structures. One third of them ar

6、e apparently not associated with UV continuum sources that are bright enough to produce Ly emission.,Possible Models of Lyman Alpha Emission,Photo-ionization by obscured UV sources like an AGN or starburst Chapman et al. ApJ, 606, 85 (2004)Cooling radiation from gravitationally heated gas in collaps

7、ed halos Haiman, Spaans & Quataert, ApJ, 537, L5 (2000) Fardal et al., ApJ, 562, 605 (2001)Shock heating by supernova driven galactic outflows Taniguchi & Shioya, ApJ, 532, L13 (2000) Mori, Umemura & Ferrara, ApJ, 613, L97 (2004) Mori & Umemura, Nature, 440, 644 (2006),We consider a forming galaxy u

8、ndergoing multitudinous SN explosions as a possible model of bright extended LAEs. To verify this model, an ultra-high-resolution hydrodynamic simulation is performed using 10243 grid points, where SN remnants are resolved with sufficient accuracy. Three-dimensional hydrodynamics (AUSM-DV)Gravity of

9、 dark matter halosRadiative cooling (including H2 molecule and metals)Star formation Supernova feedback (thermal energy and metals)Stellar emission: population synthesis model by Fioc 1997 (PGASE)Gas emission: Optically thin and collisional ionization equilibrium Sutherland & Dopita 1993 (MAPPING II

10、I),Three-dimensional Hydrodynamic Model of Bright Lyman-alpha Emitters,Parameters,Total mass : 1011 M , Total gas mass: 1.3x1010 M (M=0.3, =0.7, h=0.7, z=7.8, b=0.024 h-2)Sub-galactic system: N-body dynamics (20 bodies ) According to the general picture of bottom-up scenarios for galaxy formation, w

11、e model a proto-galaxy as an assemblage of numerous sub-galactic condensations building up the total mass of a galaxy. This sub-galactic unit has a mass of 5x109 M and virialize at z=7.8.Star formation : Shmidt law cool ff cros d* / dt = C* g / ff Local star formation efficiency: C*=0.1 Salpeters IM

12、FSupernova feedback: ESN = 1051 erg / SN (thermal energy) Oxygen : 2.4 M / SN,These bubbly structures (middle panels in right fig.) suggest that supernova events could be closely related to observed LAEs. So we think these complexes of various super-bubbles driven by multiple supernovae are an attra

13、ctive explanation for LAEs.,Simulation result,Movie http:/www.ccs.tsukuba.ac.jp/Astro/Members/mmori/nature/Mori.mpg,SED : Gas and Stars,The red (blue) lines indicate the emission from gas (stellar) component. In the first 300 Myr, the resultant Ly luminosity from gas component is more than 1043 erg/

14、s . This completely matches the observed Ly luminosities of Bright Ly emitters.After 300 Myr, the luminosity declines to less than the observed level. Then, the SED becomes dominated by stellar continuum emission.,Matsuda et al. 2004,Smoothed image,Upper: Projected distribution of Ly emission derive

15、d by numerical results.Lower left: Simulation result smoothed with a Gaussian kernel with a FWHM of 1.0”Lower right: Ly image of the LABs observed by Matsuda et al. (2004),Comparison of simulation and observation,L Ly LUV LAE phase,Evolution of Ly emission andstellar continuum emission,The results o

16、f our simulation indicate the possible link among LAEs and LBGs. The simulated post-starburst galaxy with the age of 1 Gyr can correspond to LBGs. It is implied that LBGs are the subsequent phase of LAEs.,Subsequent dynamical evolution with N-body simulation containing million particles,The virializ

17、aion of the total system is almostcompleted 3 Gyrs. Stellar mass: 1.11010 M Velocity dispersion: 133 km s-1 Effective radius: 3.97 kpc MB= -17.2, MV= -18.0, U-V=1.15, V-K=2.85,Surface brightness profile,Mori & Umemura 2006,Part IIExtended model,Observational properties,Compact LAEs Extended LAEsLya

18、luminosity: 1042-43 1042-44 erg s-1 Size (Lya): a few kpc 10-100 kpcMorphology: UV: compact scattered Lya: extended very extendedStellar mass: 108-10 M 1010-11 M SFR: 110 M yr-1 10 100 M yr-1,3D hydrodynamics model,We consider a forming galaxy undergoing multitudinous supernova explosions as a possi

19、ble model of Lyman emitters. Three-dimensional hydrodynamics Gravity of DM halos (fixed potential in each halo)Radiative cooling (metals dependent)Star formation and supernovaTotal mass : 108-12 M , Total gas mass: 1.3x107-11 MDark Matter: NFW profile, Gas: Constant densityStar formation : cool ff c

20、ros crit=0.1 cm-3 d* / dt = C* g / ff , Salpeters IMFSupernova feedback: ESN = 1051 erg, Oxygen : 2.4 M,Evolution of mass and metallicity,Stellar mass Gas mass Gas metallicity,Lyman alpha emission,1012,1011,1010,109,108,Gas cooling radiation Stellar origin (HII),Llya , Case B = SFR / 9.1x10-43 (Kenn

21、icutt 1998),Collisional ionization and excitation,Origin of Lyman alpha photons,Red: cooling radiation (collisional ionization and excitation) Blue: Prediction by Kennicutts relation : SFR = 9.1x10-43 Llya (Kennicutt 1998),Spatial distribution of Lyman alpha emission,M=109M z=8.1 M=1010M z=6.2 M=101

22、2M z=3.0 1 arcsec=4.8 kpc 5.6 kpc 7.7 kpc,Theoretical Ly emission comes mainly from high density regions. The filamentary structures are produced by the galaxy merger and multiple SN explosions. At the lower redshift, these galaxies with the complicated structures are observed as Lyman alpha blobs.

23、But the higher redshift, most of structures become unclear due to the limited resolution.,Summary,We have suggested that Ly emitters can be identified with primordial galaxies catched in a supernova-dominated phase. The bubbly structures produced by multiple SN explosions are quite similar to the ob

24、served features in Ly surface brightness of Ly emitters. The resultant Ly luminosity can account for the observed luminosity of Ly emitters. After 1 Gyr the simulated galaxy is dominated by stellar continuum radiation and looks like the Lyman break galaxies. At this stage, the metal abundance reache

25、s already the level of solar abundance. As a result of purely dynamical evolution over 13 billion years, the properties of this galaxy match those of present-day elliptical galaxies well. The results of our simulation indicates the possible link between Ly emitters and Lyman break galaxies. The major episode of star formation and chemical enrichment in elliptical galaxies is almost completed in the evolutionary path from bright Ly emitters to Lyman break galaxies.,