MSFC. Abstract. WFXT AGN Detections 2.
WFXT AGN Detections2
The Wide Field X-ray Telescope (WFXT)1is a proposed mission that will revolutionize the study of active galactic nuclei (AGN). WFXT will detect 107 AGN over the entire AGN luminosity versus redshift plane, including millions of obscured AGN, thousands of AGN at z > 6, and even hundreds of bona fide Compton-thick AGN at z > 12. Through X-ray spectroscopy, WFXT will measure obscuration for 3×105 AGN and redshifts for 105 AGN. Source identification and The WFXT surveys will be synergistic with other wide-field surveys at other wavelengths like the Large Synoptic Space Telescope and Wide-Infrared Survey Explorer. As X-ray emission is a universal feature of accretion, X-ray selected samples of AGN tens to hundred of times that of SDSS3 will critically probe the earliest stages of black hole and galaxy formation, the dependence of cosmic accretion history on galaxy merging and environment, and the history and duty cycle of nuclear activity in a galaxy lifetime.
Understanding The Growth And Evolution OfSuper Massive Black Holes With The WFXT
Key Question I:When & how did the first supermassive black holes form?
Key Question II:
How does environmentregulate nuclear activity?
Key Question III:
What is the history of nuclear activity in a galaxy lifetime?
What is the lifetime of an AGN?
AGN lifetimes are currently poorly constrained, ranging from 106 − 108 yr16,17. The ratio between the space densities of AGN and the host dark matter halos can constrain this lifetime18.
Observations4,5,6and theory7,8support the coevolution of supermassive black holes and their host galaxies; however, important questions remain.
The role of galactic environment − void, filament, group, or cluster − is still a matter of great debate (e.g., mergers, flyby interactions, different accretion modes), and is one of the largest unanswered questions in AGN science.
How many high redshift AGN exist?
High redshift AGN have had little time to form. Thus, their space density depends critically on several important unknown AGN properties: Where do AGN form? What triggers AGN formation? At what rate do AGN accrete? Such parameters leads to large scatter in predicted space densities9,10,11.
How variable are AGN?
AGN exhibit variability on minute to year timescales. This variability arises from changes in obscuration19 and due to intrinsic properties like black hole mass and luminosity20.
What are the properties of AGN as functions of
[Right] XMM observations of H0557-385, a nearby Seyfert 1 exhibit a factor of ten variability in 4 years19. This is thought to arise from variable absorption.
[Left] Log N - log S (0.5 – 2 keV) measurements of X-ray point sources are overlaid by predictions forz > 6 AGN according to four diﬀerentmodels (magenta lines as labeled). The sensitivity limits of the WFXT surveys are indicated by vertical dashed lines.
G. Sivakoff1, S. Murray2, R. Gilli3, P. Tozzi4, M. Paolillo5, N. Brandt6,P. Rosati7, S. Borgani8, A. Ptak9, R. Hickox10, W. Forman2, & the WFXT Team1UVa, 2CfA, 3INAF-AOB, 4INAF-AOT, 5Univ. Of Naples, 6PSU, 7ESO, 8Univ. Of Trieste, 9JHU, 10Durham Univ.
constrain AGN lifetimes in a variety of AGN subsamples
systematically detect variability (Δf/f > 20%) in 105 AGN
reconstruct mass and accretion rate for ~5000 AGN
Do galaxies grow before black holes, or do black holes grow before galaxies?
Recent comparisons of the black hole mass – bulge mass relation at z~2 to the local relation suggest some galaxies grow before black holes12; however, results at high redshifts suggest the opposite13. Current results have large statistical errors, and there are likely biases to be resolved.
Synergy with other surveys and missions
WFXT is the only X-ray mission that will match the sensitivity and survey area of the next generation wide-area O/IR & radio surveys. WFXT will also serve as the source for targeted follow-up (e.g., ALMA can be used to measure the mass of the host galaxies of the highest redshift AGN).
nSource ID By Combining X-ray/Optical/Infrared/Radio
Wide Survey: PanSTAARS + Euclid sufficient (I~24, K~22)
Deep Survey: LSST + Euclid sufficient (I~27, K~24)
Photo-z (PanSTAARS/LSST) + Spectro-z (BOSS/Euclid)
Redshifted Fe line detected by WFXT -> X-ray redshift for 105 obscured AGN
[Left] Distribution of SDSS DR3 quasar subsample15bolometric luminosity with redshift. The SDSS DR7 quasar catalog contained ~105 AGN, but only covered the most luminous AGN. The sensitivity limits of the three WFXT surveys (assuming a 0.5-2 keV bolometric correction of 20) indicate the large improvement WFXT will provide.
[Left] Black holes in local ULIRGS (purple) and sub-mm selected galaxies (red) are under-massive given their host galaxies when compared to typical local AGN12. This suggests galaxy growth leads black hole growth.[Right] Four high redshift AGN have large black hole masses when compared to typical local AGN13.
[Right] Two SEDs of z=6 quasars are overlaid with the sensitivity of planned O/IR missions and the WFXT Medium survey. There is strong synergy in both sensitivity and survey area.
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