the effects of x rays on star formation and black hole growth in young galaxies
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The Effects of X- rays on Star Formation and Black Hole Growth in Young Galaxies. Marco Spaans (Kapteyn, Netherlands). Ayçin Aykutalp (Kapteyn), John Wise (Georgia), Rowin Meijerink (Kapteyn/Leiden ). BHs.

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the effects of x rays on star formation and black hole growth in young galaxies

The Effects of X-rays on Star FormationandBlack Hole Growth in Young Galaxies

Marco Spaans

(Kapteyn, Netherlands)

AyçinAykutalp (Kapteyn), John Wise (Georgia), Rowin Meijerink (Kapteyn/Leiden)

  • ManygalaxiescontainBHs : MBH~10-3Mbulge
  • NeedaccretionontoseedBHsand the formation of Pop III andPopII/I at earlytimes
  • Even z~6 SMBHs of 109 Mexist
  • Possibleevolution in Magorrian rel. at high z(Walter ea 04)
  • BHsproduce UV and X-rayradiation: feedback
  • SeedBHsformed as remnants of Pop III stars or throughsingularcollapse in primordialatomiccoolinghalos. The latterrequires a strong UV background (103-5 J21) and/or Lyman α trapping(Bromm & Loeb 03, Spaans & Silk06, Shangea 08, Dijsktraea 08, Inayoshi & Omukai12)
  • σ ~ E-3

1keV  1022 cm-2 penetration

    • Secondary Ionizations Dominate
  • FX =84 L44 r100-2 erg cm-2 s-1
  • X-ray flux over 1-100 keV with a power law E-0.9

 think of a Seyfert AGN at 100 pc

e 1 kev
E > 1 keV
  • Heating: X-rayphoto-ionizationfastelectrons; 10-50% H and H2vibexcitation; UV emission (Ly α, Lyman-Werner)
  • Cooling: [FeII] 1.26, 1.64; [OI] 63; [CII] 158; [SiII] 35 μm; CO thermalH2 vib; gas-dust
  • 1 keVphotonpenetrates 1022 cm-2 of NH
  • Heating efficiency 10-50%
  • X-rays penetrate further than UV
  • High opacity of metal-rich gas  Large energy deposition rate (~FX/nH)
  • X-rays ionize and drive the ion-molecule chemistry, hence the H2 formation
simulations 1
  • Box sizeof 3Mpc/h
  • 3.6 pcproperresolution
  • Include X-ray chemistry by porting XDR code (Meijerink&Spaans 05): dust & ion-molecule chemistry, heating, cooling (escape probability for lines); pre-computed tables in nH, NH, FX, and Z/Z(176 species, more than 1000 reactions)
  • Employ Moray(Wise et. al. 12): UV and X-ray radiation transport (polychromatic spectrum) around the seed BH and every star particle
  • XDR (metallicity dependent) + Enzo non-equilibrium chemistry (9 species) run in parallel
simulations 2
  • Considersingularcollapsescenariofor UV backgrounds of 103 J21and 105 J21, whichfacilitatedestruction of H2andsuppressesfragmentation
  • Introduceseed BH M=5 x 104 M at z=15
  • BH at 10% Eddington(Kim et. al. 11 prescrip.) produces UV (90%) and X-ray (10%)
  • Star formationrecipesfor Pop III (H2 > 5 x 10-4) and Pop II/I (Z > 10-3.5 Z) from z=30
  • SN feedback, metal enrichmentfollowed

High opacity effect of metal enriched gas









Density-temperature (left) and column density-radius (right) profiles for zero and solar metallicity cases at z=14.95 (top) and z=14.54 (bottom).

h 2 fraction


H2 Fraction


Low (103 J21) and high (105J21) UV bg. cases at z=14.95 (left), 14.86 (middle), and 14.78 (right).

pop iii stars
Pop III stars

Low UV bg, at z=14.95!!!

accretion rate
Accretion rate
  • High UV bg case: 105 J21
  • Low UV bg case: 103 J21
bh growth
BH growth

Strong UV background prevents growth to a SMBH!

X-ray feedback/BH growth self-regulating

x ray flickering
X-ray flickering







hii region
HII region

High UV bg case,

at z=12.86

  • X-rays important & metals boost X-rayopacity heating
  • Weaker 103 J21 UV background allows Pop III star formationandenrich the medium withmetals
  • X-ray feedback/BH growth is self-regulating
  • Singularcollapse scenario does notyieldSMBHs at z=6 for 105 J21 UV background
  • Interestingthoughforslowlyevolvingdwarfstoday, unlessthere is later time UV weakeningand/or metal enrichment
  • For low UV bg, 105 M MBH grows at 10-3 M/yr, doubles in mass in Edd. time (usual suspects forSMBHs at z=6)
  • 3 Mpc/h box size: Merger rate, maximum halo mass underestimated
  • No Jets included
  • Self-shielding approximated locally
  • No UV background evolution
  • The simulations are still running!!!