Title: X-ray%20Bright,%20Optically%20Normal%20Galaxies%20-%20XBONGS%20Forman,%20Anderson,%20Hickox,%20Jones,%20Murray,%20Vikhlinin,%20Kenter%20and%20the%20Bootes%20Team
1X-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)
2The XBootes Survey
- 126 ACIS 5 ksec pointings
- Joint GTO (Murray) and GO (Jones) program
- 14h 32m 34? 06
- 4642 sources detected (gt2 cts)
- 625 spurious
- 3293 sources detected (gt4 cts)
- 22 spurious
- 42 extended sources (gt10 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
3Spectroscopy in Bootes
- MMT/Hectospec fiber spectrograph
- 300 fibers
- 6 A resolution, 4000-8000A
- Spectroscopy
- Complete X-ray gt4 cts and Ilt21.5 and galaxies
Ilt19.5 - 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 lt z lt 1
4Heterogeneous Class of Objects
- From optical SEDs and morphology
- Red Ellipticals 60
- Blue Ellipticals 84
- Interacting 21
- Spirals 9
- AGN 12
- (Fioc Rocca-Volmerange 1997 Francis et al. 1991)
5Redshift Distribution
XBONGS Broad line AGN Narrow line AGN
XBONGS and NL AGN same distribution
6XBONG Magnitude Distribution
XBONG BL (zlt1) 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
7Luminosity Distributions
- 200 XBONGs with Lxgt1042 erg/s
- 50 with Lxgt1043 erg/s
- XBONGs and NL AGN
- Similar Lx
- Similar Fx/FR
- Argues against dilution for all of
- sample
XBONG BL (zlt1) 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
9IRAC Color-Color Diagrams (following Stern et al.)
BL AGN
XBONGS BL AGN NL AGN
0.45ltZlt0.60
Zlt0.15
0.60ltZlt0.75
0.15ltZlt0.30
Red Blue
0.75ltZlt1.00
0.30ltZlt0.45
zlt0.3 Dilution - about 30 consistent with
Georgantopoulos et al.
dilution criterion zgt0.3 XBONGS
concentrated under AGN wedge
10Radiatively 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 lt 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 lt 0.01
- VIABLE MODEL - needs detailed SEDs
11Conclusions
- 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
nH1022 cm-2 - Many sources show little (lt1022 cm-2) absorption
- RIAF (radiatively inefficient accretion flow)
- Spheroidal sample has low Eddington ratio
(Lbol/Leddlt0.01) - Probably some BL Lacs
- XBONGs are a heterogeneous class
12Future 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 SEDs 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
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14MMT 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.