Transcript Document

Black Holes in the Deepest
Extragalactic X-ray Surveys
Chandra X-ray Observatory
Angular res. and positions improved by factor ~ 10.
X-ray Multi-Mirror Mission-Newton
Photon collection improved by factor ~ 10.
50-250 times sensitivity of previous missions.
Both operating well and can likely continue for ~ 5-10 more years.
X-ray Imaging Optics
X-ray CCD Detectors
XMM-Newton EPIC
Chandra ACIS
The Cosmic X-ray Background
X-rays from Active Galaxies
Nuclear Obscuration in Active Galaxies
Obscuring “Torus”
Cut-Through View
Three Important Reasons to Survey in X-rays
1. X-ray emission universal property of accreting supermassive black holes
2. Penetrating; reduced absorption bias
X-ray emission can penetrate and measure large
amounts of absorbing material.
Majority of active galaxies are absorbed.
Absorption bias drops going to high redshift.
3. Low dilution by host-galaxy light
Penetrating Power of X-rays
Many Complementary X-ray Surveys Ongoing
Blue = Chandra
Green = XMM-Newton
Red = ROSAT
About 35 ongoing surveys with
Chandra and XMM-Newton.
Usually performed in regions
with strong multiwavelength
data and / or notable objects.
Together the surveys cover a
broad part of the sensitivity vs.
solid-angle “discovery space”.
I will focus on results from the
deepest X-ray surveys.
Equally important results from
wider X-ray surveys!
Supporting Multiwavelength Data: HST
Supporting Multiwavelength Data: Spitzer
Supporting Multiwavelength Data:
Submillimeter
James Clerk Maxwell Telescope
Mauna Kea, Hawaii
The Deepest X-ray Surveys to Date
The Chandra Deep Field-North (CDF-N)
The CDF-S and Extended CDF-S
250 ks to 2 Ms coverage
1125 arcmin2 (~ 150% Moon)
~ 990 point sources
Matching of X-ray and Optical Sources
Optical Spectroscopic Follow-Up
Observations to Get Redshifts
Keck Observatory
Very Large Telescope
Follow-Up Challenges and Results
X-ray Number Counts for
Chandra Deep Fields
50-70% spectroscopic completeness overall. Good completeness to I ~ 23-24.
Hundreds of very faint sources, often with weak-to-moderate line emission. Further deep spectroscopy
needed to identify these. Likely are obscured AGN at z ~ 1.5-6.
More than 70% of sources are z ~ 0.1-5 AGN. AGN source density ~ 7200 deg-2.
Also many starburst and normal galaxies. Rapidly rising population to faintest X-ray fluxes.
Highlights on Some Key Topics
Number-density and spectral evolution of AGN.
AGN content of distant submillimeter galaxies.
Other great topics: Host galaxies, AGN clustering,
variability, absorption, starburst & normal galaxies,
clusters & groups.
Evolution of Luminous Quasars
Luminosity Dependent AGN Evolution
Number-Density Changes for AGN of Different Luminosities
Probe evolution of moderate
luminosity AGN. More numerous!
Lower luminosity AGN peaked
later. Called “anti-hierarchical
growth” or “cosmic downsizing.”
Basic result appears robust to
incompleteness, but details
still uncertain.
More “frugal” X-ray universe
than some expected before
Chandra and XMM-Newton.
X-ray background not dominated
by many obscured quasars.
AGN make ~ 5-10% of the power
in the Universe since the formation
of galaxies (not ~ 50%).
Black-Hole Accretion Versus
Cosmic Star Formation
SFR density
Scaled SMBH
accretion-rate density
Accretion-rate density and cosmic star-formation rate density similar to first order.
Luminosity Dependence and Evolution of AGN Spectra
X-ray strong
BQS
BQS
SDSS
z>4
snapshots
E-CDF-S
SDSS
Seyfert 1s
X-ray weak
E-CDF-S
BQS
SDSS
SDSS
E-CDF-S
z > 4 snapshots
Luminosity dependence of X-ray vs. total power. X-ray fraction declines with luminosity. Not understood.
No detectable redshift dependence. X-ray-to-optical flux ratios of AGN change by < 30% from z = 0-6.
Despite large number-density changes, individual AGN “unit” is remarkably stable over ~ all of cosmic history.
AGN Content of Distant Submillimeter Galaxies
Submm from dust-shrouded starbursts forming stars at ~ 1000 solar masses / year.
James Clerk Maxwell Telescope
Mauna Kea, Hawaii
About 1000 times more common at z ~ 2 as today.
Likely seeing the epoch of spheroid formation in massive galaxies at z ~ 1.5-4.0.
Submm sources in 2 Ms Chandra Deep Field-North
Green = X-ray detected submm sources (17/20)
Yellow = X-ray undetected submm sources (3/20)
Can we see the black hole growing
inside the forming spheroid?
About 85% of submm galaxies with
precise positions have detections in
Chandra Deep Field-North.
Detection fraction much higher than
for any other coeval galaxy population.
Most appear to contain obscured AGN.
Seeing simultaneous growth of black
hole and spheroid in “pre-quasar”
phase?
0.5-8 keV image
Pushing Back the “Edge” of the X-ray Universe
Chandra has not yet reached its
natural limits.
Can go much deeper while remaining
confusion free and largely photon
limited.
• Heavily
obscured AGN that are currently
missed
• Better photon statistics for better X-ray
spectra and variability
• Normal and starburst galaxies
Prospects for the Long Term
NuSTAR
eROSITA
International X-ray Observatory