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Super- Eddington Accreting Massive Black Holes as Long-Lived Cosmological Standards

Super- Eddington Accreting Massive Black Holes as Long-Lived Cosmological Standards. Background. The maximum brightness of type Ia supernovae are nearly the same which makes them standard rulers. However, SNe Ia beyond are rare.

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Super- Eddington Accreting Massive Black Holes as Long-Lived Cosmological Standards

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  1. Super-Eddington Accreting Massive Black Holes as Long-Lived Cosmological Standards

  2. Background • The maximum brightness of type Ia supernovae are nearly the same which makes them standard rulers. • However, SNeIa beyond are rare. • We need new distance indicators to further probe dynamics of the acceleration.

  3. The new ruler – SEAMBH • Super-Eddington accretion onto black hole is feasible in slim disk. • Photons are trapped inside the accretion flows and are advected into the black holes. • Photon trapping results in a saturated luminosity: ①

  4. Two essential issues • How to identify SEAMBH? • How to test ① and its uncertainties through observation?

  5. Identify SEAMBH • They are predicted to have unique optical-UV spectral characteristics, but cannot be identified only in optical-UV. • X-ray spectroscopy allows such identification for their two properties which are easy to measure with modern observations.

  6. There is a positive correlation between the 2-10 keV x-ray spectral index Γ and the Eddington ratio . • Higher sources emit a smaller fraction of their total radiation at hard x-ray energies.

  7. The simplest model for the slim disks of SEAMBHs assumes a spherical hot corona. • The x-ray photon index can be approximated by . • The coronae having a Comptonization parameter of , then the SEAMBHs are characterized by .

  8. The best group of AGNs where such processes have been studied are NLS1. • We selected a large number of NLS1s with hard x-ray observations by ASCA, XMM-Newton, Chandra, Swift. • We examined the in our sample and found many of them indicate super-Eddingtonratios, up to 5 or even more.

  9. Test the basic equation ① • We have to estimate which can be measured by reverberation mapping technique, but now such mappings are not available.

  10. We can use the empirical correlation between BLR and the continuum luminosity acquired from about 35 AGN: ② • ② enable us to obtain the BH mass: ③

  11. Noting that , we obtain the expression : ④

  12. We use the distance modulus and compare it with the standard luminosity distance . • We predict to get smaller for larger Γ, and this can be understood by:

  13. Advantages of SEAMBHs • The saturated luminosity have no potential cosmic evolution. • They are abundant at high-z and are very luminous. • Repeated observations can be made to improve the observational accuracy.

  14. Observational issues • is the one obtained for all AGNs, not NLS1 or SEAMBH. • The 2-10 keV luminosity and slope are variable which need longterm averaged value to improve accuracy.

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