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X-ray Bright, Optically Normal Galaxies - XBONGS Forman, Anderson, Hickox, Jones, Murray, Vikhlinin, Kenter and the Bo

X-ray Bright, Optically Normal Galaxies - XBONGS Forman, Anderson, Hickox, Jones, Murray, Vikhlinin, Kenter and the Bootes Team . Bootes Survey 9.3 sq. degrees with Chandra 4632 X-ray sources 1600 optical spectra NOAO Deep Wide Field Survey AGES Optical Spectroscopic Survey

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X-ray Bright, Optically Normal Galaxies - XBONGS Forman, Anderson, Hickox, Jones, Murray, Vikhlinin, Kenter and the Bo

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  1. X-ray Bright, Optically Normal Galaxies - XBONGS Forman, Anderson, Hickox, Jones, Murray, Vikhlinin, Kenterand the Bootes Team Bootes Survey 9.3 sq. degrees with Chandra 4632 X-ray sources 1600 optical spectra NOAO Deep Wide Field Survey AGES Optical Spectroscopic Survey 20,000 galaxy spectra Key to success is contiguous area and efficient spectroscopy with Hectospec XBONGS - debated nature since Einstein Obs. (Elvis et al. 1981) Dilution of optical AGN signature by galaxy light Absorption Radiatively inefficient accretion flow (little optical/UV)

  2. The XBootes Survey • 126 ACIS 5 ksec pointings • Joint GTO (Murray) and GO (Jones) program • 14h 32m +34 06’ • 4642 sources detected (>=2 cts) • 625 spurious • 3293 sources detected (>=4 cts) • 22 spurious • 42 extended sources (>=10 cts) • fmin= 4(8)x10-15 erg cm-2 s-1 (0.5-7 keV) • 98% sources 4 cts matched to NDWFS candidates (R26) Murray et al. ApJ S 163, 2005 Kenter et al. ApJ S 163, 2005 Brand et al. ApJ, 2006

  3. Spectroscopy in Bootes • MMT/Hectospec fiber spectrograph • 300 fibers • 6 A resolution, 4000-8000A • Spectroscopy • Complete X-ray >4 cts and I<21.5 and galaxies I<19.5 • 1,531 X-ray selected and ~19,000 galaxies • 1175 Broad Line Galaxies • 50 Narrow Line Galaxies • 258 XBONGS • Huge sample • 17% of total • 0 < z < 1

  4. Heterogeneous Class of Objects From optical SED’s and morphology • Red Ellipticals 60 • Blue Ellipticals 84 • Interacting 21 • Spirals 9 • “AGN” 12 (Fioc &Rocca-Volmerange 1997; Francis et al. 1991)

  5. Redshift Distribution XBONGS Broad line AGN Narrow line AGN XBONGS and NL AGN same distribution

  6. XBONG Magnitude Distribution XBONG BL (z<1) NL XBONG counterparts similar to NL/BL AGN possibly somewhat fainter than NL AGN Argues against significant dilution of lines by underlying host galaxy for all of sample

  7. Luminosity Distributions • 200 XBONGs with Lx>1042 erg/s • 50% with Lx>1043 erg/s • XBONG’s and NL AGN • Similar Lx • Similar Fx/FR • Argues against dilution for all of • sample XBONG BL(z<1) NL

  8. Merged X-ray Spectra Type (90% error) and no absorption Red Ellipticals 1.12-1.32 Blue Ellipticals 1.55-1.73 “AGN” 1.83-2.25 Interacting 1.28-1.56 (confirmed by hardness ratios) Red ellipticals - for an assumed=1.9 power law nH ~ 0.7-1.1 x 10 22 cm-2(90% confidence) • Some “types” absorbed, some not absorbed

  9. IRAC Color-Color Diagrams (following Stern et al.) BL AGN XBONGS BL AGN NL AGN 0.45<Z<0.60 Z<0.15 0.60<Z<0.75 0.15<Z<0.30 RedBlue 0.75<Z<1.00 0.30<Z<0.45 z<0.3 Dilution - about 30%; consistent with Georgantopoulos et al. dilution criterion z>0.3 XBONGS concentrated under AGN wedge

  10. Radiatively Inefficient Accretion Flows (RIAF) • At low accretion rates (Yuan & Narayan) • - Optically thick disk is truncated at Rtrans • - Interior to Rtrans flow is RIAF (radiatively inefficient; optically thin) • - Observed in high state galactic black holes • X-rays from inverse Compton in RIAF • Little optical or UV since no disk at small radii • model requires L/Ledd < 0.03 • Test RIAF model with spheroidal sample of XBONGS • -Use optical luminosity as proxy for MBH (108-109 Msun) • - MBH yields Ledd • -Derive AGN LBOL from SED (Elvis et al.) • -For 46 XBONGS, LBOL /Ledd < 0.01 • VIABLE MODEL - needs detailed SED’s

  11. Conclusions • Large XBONG sample • 258 with redshifts to 1 • Variety of optical morphologies • Origin of XBONG signature • Some dilution at low z (small fx/fR) • Some absorption - esp. red ellipticals with nH~1022 cm-2 • Many sources show little (<1022 cm-2) absorption • RIAF (radiatively inefficient accretion flow) • Spheroidal sample has low Eddington ratio (Lbol/Ledd<0.01) • Probably some BL Lac’s XBONG’s are a heterogeneous class

  12. Future Work • Deeper & Wider • Chandra and XMM-Newton • Larger samples, better S/N • X-ray spectra • Better models applied to ensemble of spectra • Optical spectra for fainter sources • Probe to higher z • Detailed analysis of optical spectra • Derive equivalent widths and line strength limits • Model NL galaxies, compare to XBONGS • Derive SED’s for different classes to test e.g., RIAF models • Study local environment • 20,000 galaxy redshifts • Measure local density, compare to other AGN classes Remarkable class Promises new insights into accretion process

  13. MMT Bootes survey Optical spectroscopy: AGES survey w/ MMT/Hectospec The first sample contains ~1000 broad line AGNs, 80 narrow-line AGNs, and 27,000 “normal” galaxies.

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