November 2006 1

Megan E. Eckart

Caltechwith Fiona Harrison, David Helfand,

Daniel Stern, Luke Kotredes

The SEXSI Survey: Recent Progress

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Overview

• Introduction to the SEXSI sample and optical followup

• Highlights of the optical/X-ray sample composition

• Spitzer data – high-z type 2 quasar candidates– SED’s of spectroscopically ID’d sources

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SEXSI Survey

• Study dominant contributors to XRB

• 1034 2-10 keVsources from 27 Chandra pointings; (2 deg2)

• R-band imaging

• 438 spectroscopic redshifts from Keck

Harrison et al. 2003, ApJ, 596, 944-956 (Paper 1)

4Harrison et al. 2003, ApJ, 596, 944-956 (Paper 1)

SEXSI Survey

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Redshift Distribution

• Peak: z ~ 0.7

• 34 narrow-lined Lx>1044 sources(type-2 quasar candidates)

• nine z > 2, obscured type-2 quasar candidates

Eckart et al. 2006, ApJS, 165, 19-56 (Paper 3)

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Fraction Obscured

• SEXSI - excellent statistics over flux range

~50% obscuredindependent of luminosity

log (Unobscured 2-10 keV Luminosity [erg s-1])

Fra

ctio

n w

ith lo

g(N

H)

> 2

2

Eckart et al. 2006, ApJS, 165, 19-56 (Paper 3)

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Spitzer Data

• Spitzer data over five SEXSI fields

(IRAC & MIPS)

• 250 SEXSI X-ray sources covered

• 140 with spectroscopic ID

•62% of total X-ray sources are in “wedge”

• 86% of BLAGN

• 67% of NLAGN

• 28% of ELG

• 15% of sources with Lx<10 43.5 erg s-1

- wedge from Stern et al. (2005)

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High-z QSO 2

- quadrant split from Martinez-Sansigre, Lacy et al. (2005)

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High-z QSO 2

- quadrant split from Martinez-Sansigre, Lacy et al. (2005)

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BLAGN SED’s

• Many BLAGN fit a typical quasar SED (Elvis et al. 1994)

•BUT, there are many that fit a star forming template better in mid-IR/optical (Devriendt et al. 1999 template plotted above)

log ( [Hz]) log ( [Hz])

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NLAGN SED’s

• Fits star forming template in IR • Bad match to both templates

•(would match an absorbedAGN spectrum …)

log ( [Hz]) log ( [Hz])

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ELG SED’s

• Overwhelming majority (but not all) of ELG fit starforming template

log ( [Hz])

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In Progress…

Synthesis of spectrally identified and unidentified SED’s

X-ray stacking of Spitzer sources with Chandra nondetections

Acknowledgements: Fiona Harrison, David Helfand, Dan Stern, Luke Kotredes

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