Download Massive Disruptions in the Cool Core of MACS J1931.8-2634 Steven Ehlert

Massive Disruptions in the Cool Core
of MACS J1931.8-2634
Steven Ehlert
Kavli Institute for Particle Astrophysics and Cosmology
Stanford University & SLAC
Snowcluster March 31st 2010
MACS J1931 Steven Ehlert
Overview
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Counteracting cooling flows in nearby clusters.
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More extreme cooling rates in MACS 1931.
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Observations of MACS 1931 in X-ray, Optical, and Radio.
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What has happened to the cool core in MACS 1931?
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All figures and results preliminary!
Snowcluster March 31st 2010
MACS J1931 Steven Ehlert
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X-ray:
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Stanford: Steve Allen, Aurora Simionescu, Norbert Werner, Evan
Million, Glenn Morris
Cambridge: Andrew Fabian, Jeremy Sanders, Robert Dunn
Optical:
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Collaborators
Stanford: Anja von der Linden, Patrick Kelly, Doug Applegate,
Mark Allen
University of Hawaii: Harald Ebeling
Radio:
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University of New Mexico: Greg Taylor, Gianfranco Gentile
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MACS J1931 Steven Ehlert
Suppressing Cooling Flows
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Nominal cooling rates based on X-ray luminosities are
usually far larger than spectroscopically measured cooling
rates and observed star formation.
Feedback due to a central AGN seems to play a critical role
in suppressing the expected cooling flows.
Small scale physics of AGN feedback is still ambiguous and
manifests itself through multiple physical processes.
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MACS J1931 Steven Ehlert
Feedback in Virgo
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Nominal cooling rate of 20
-1
M⊙ yr in Virgo balanced
by M87.
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Clear filaments and shocks
here.
Lots more from Norbert
following this talk!
MACS J1931 Steven Ehlert
Feedback in Perseus
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The Perseus Cluster with
NGC 1275 at its center.
Nominal cooling rate of
400 M⊙ yr-1.
Clear ripples, cavities, and
waves heating the ICM.
MACS J1931 Steven Ehlert
Turning the Cooling Rate up to 1000
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What happens in clusters that have even larger nominal
cooling rates?
Can AGN feedback supply enough energy to counteract the
large radiative losses?
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Does a residual cooling flow exist?
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Can we observe smaller scale processes at work?
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To help answer these questions, we have done a detailed
multiwavelength analysis on MACS 1931....
Snowcluster March 31st 2010
MACS J1931 Steven Ehlert
MACS 1931 in a Nutshell
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One of the brightest cooling cores in the sky: bolometric
luminosity is ~1045 erg s-1 within 50 kpc of center.
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At a redshift of z=0.352.
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Large nominal cooling rate: ~1000 M⊙ yr-1.
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Contains an X-ray bright central AGN and clear X-ray
cavities.
We focus our attention on the interplay between the ICM,
star formation, and the central AGN.
Snowcluster March 31st 2010
MACS J1931 Steven Ehlert
Observational Data
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Two Chandra observations with ~100 ks total clean
exposure.
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Deep multiband optical imaging (BVRIz) with Subaru.
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1.4 GHz VLA radio data (A configuration).
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MACS J1931 Steven Ehlert
Chandra Imaging
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Processed, flat-fielded
image in energy range of
0.7-2.0 keV.
General north-south
elliptical symmetry.
MACS J1931 Steven Ehlert
Chandra Imaging: Isophotes
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Isophote centroid is
changing with distance.
Orientation angle of major
axis also changing.
MACS J1931 Steven Ehlert
Chandra Imaging: Residuals
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Model continuum as
elliptical β-model.
After subtracting model
from image, adaptive
smoothing gives the image
on the left.
Bright spiral of gas
indicates oscillatory core
motion.
MACS J1931 Steven Ehlert
Chandra Imaging: Zoom
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What structures exist
around the central AGN?
Zoom in on the box.
MACS J1931 Steven Ehlert
Chandra Imaging: Around the AGN
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Several regions of interest:
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The central AGN point
source.
The X-ray cavities to the
east and west of the AGN.
The bright arcs of ICM
offset from the AGN to the
north and south.
Diffuse emission to the
south.
MACS J1931 Steven Ehlert
Chandra Imaging: Bandpass Filter
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Snowcluster March 31st 2010
High-frequency bandpass
filter was applied to
image to reveal small
scale structures.
MACS J1931 Steven Ehlert
Temperature Structure
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Contour binning (Sanders
2006) used to create
thermodynamic maps.
SN of 30 (~ 1000 counts)
per bin gives 60 regions.
Here is the temperature
map.
Errors ~15-20% based on
temperature.
MACS J1931 Steven Ehlert
Temperature Structure: Spiral
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Spiral in residuals
coincides very well with a
spiral of cool gas to the east
and north.
6 independent regions of
cooler gas correspond to
the spiral.
MACS J1931 Steven Ehlert
Temperature Structure: Zoom
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Looking more carefully at
the center of the cluster...
MACS J1931 Steven Ehlert
Temperature Structure: Around the AGN
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Hot regions to the east and
west of AGN.
Coldest gas to north of
AGN.
White exclusion region at
center is 2.5'' for AGN.
Separation between AGN
and coldest gas is ~25-30
kpc.
MACS J1931 Steven Ehlert
Entropy Structure
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Corresponding entropy map
for MACS 1931.
MACS J1931 Steven Ehlert
Entropy Structure: Zoom
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Zooming in to the central
regions...
MACS J1931 Steven Ehlert
Entropy Structure: Around the AGN
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Lowest entropy gas clearly
separated from the region
around the AGN.
In the same region as the
coolest gas.
MACS J1931 Steven Ehlert
Metallicity Profile
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Anders and Grevesse solar
metallicity model.
Metallicity profile is flat
out to ~400-500 kpc.
Best fit constant value is
0.36 solar.
MACS J1931 Steven Ehlert
Metallicity Profile
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Black line from Leccardi,
Rossetti, & Molendi 2009.
This is the average
metallicity from many
systems with cool cores.
Does a region of enhanced
metallicity exist somewhere
else in the cluster?
Any enhancements are not
azimuthally symmetric.
MACS J1931 Steven Ehlert
The Bright Offset Regions
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Two offset regions have different
thermodynamics:
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North: kT=5.4, Z=0.53
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South: kT=5.6, Z=0.17
Uncertainties: kT ~ 15-20%; Z ~
0.1.
Also measured spectroscopic
cooling rate:
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North: 180 +/- 40 M⊙ yr-1, about
40% of total luminosity in this
region.
South: < 100 M⊙ yr-1 (99% UL)
MACS J1931 Steven Ehlert
Subaru Imaging
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This is MACS 1931 in
Subaru BRz filters.
Blue points are stars in
FOV.
Central galaxy is at the
center of the box.
Highly extended and
elongated intracluster light
around the cD galaxy.
MACS J1931 Steven Ehlert
Star Formation with Subaru
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Same color bands (BRz) with
scaled I-band subtracted.
I-band emission corresponds
primarily to stellar continuum
emission.
Blue corresponds to young
stellar population and recent star
formation.
Pink is young blue stars + zband, coincident with Hα line.
Pink emission is ongoing star
formation.
MACS J1931 Steven Ehlert
Star Formation with Subaru
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This is a unusual and
unique optical morphology!
Indicates that the region of
star formation is changing
with time.
How does the star
formation correspond to the
X-ray emission?
MACS J1931 Steven Ehlert
Star Formation with Subaru
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Previous image with X-ray
contours.
H almost exclusively in
northern bright offset
region.
Star formation rate (SFR)
in northern region ~80-150
M⊙ yr-1.
In agreement with
spectroscopic cooling in
northern X-ray region.
MACS J1931 Steven Ehlert
Investigating the AGN with VLA
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Extended radio emission
surrounding the AGN.
Narrow angle tail galaxy
to the south.
MACS J1931 Steven Ehlert
Investigating the AGN with VLA
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Unusual morphology
around the AGN.
Spatially coincident with
X-ray cavities.
MACS J1931 Steven Ehlert
Calculating the Jet Power
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Calculate the 4PV
enthalpy required to
inflate the cavities (Allen
2006).
Largest source of
uncertainty is choosing
the cavities and their
volumes.
MACS J1931 Steven Ehlert
AGN Energetics
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4PV enthalpy of cavities in previous image is 6 x 1060 erg.
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This corresponds to a jet power of ~1046 erg s-1.
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Uncertainty in cavity volume puts uncertainty of 4PV & jet
power at a factor of ~2-3.
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For comparison, the AGN luminosity is ~8 x 1043 erg s-1.
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This AGN is radiatively inefficient!
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Largest jet power ever observed is ~1.7 x 1046 erg s-1 in
MS0735 (McNamara 2005).
Snowcluster March 31st 2010
MACS J1931 Steven Ehlert
Combining Data: Cool Core
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Bright offset region to the north has all of the properties of a typical
cool core:
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High density/surface brightness.
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Low temperature/entropy, enriched metallicity.
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Appreciable spectroscopic cooling rate (~180 M⊙ yr-1).
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Source of current star formation based on Hα emission consistent with
spectroscopic cooling.
Cool core is separated a large distance (30 kpc) from the central AGN.
Cooling a large contribution (~40%) of emission in the northern offset
region.
Snowcluster March 31st 2010
MACS J1931 Steven Ehlert
Combining Data: Core Motions
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X-ray and optical observations indicate oscillations of the
cool core along the north-south direction:
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Varying isophotes.
Brightness/temperature spiral.
Unusual distribution of metals.
Highly elongated intracluster light.
Snowcluster March 31st 2010
MACS J1931 Steven Ehlert
Combining Data: The Central AGN
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Central AGN is undergoing a massive outburst!
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Extended radio emission around central AGN with unusual
morphology.
Clear X-ray cavities
AGN shines brightly in X-rays.
Jet power of AGN estimated among the highest observed.
Snowcluster March 31st 2010
MACS J1931 Steven Ehlert
The Cool Core Now
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The large oscillatory motions and AGN outburst have
conspired to seriously disrupt the cool core!
Hard to separate contributions from either aspect
individually.
Cooling and star formation rates in the core remnant are
high.
Recent star formation seen to the south as well.
Very similar to what is seen in new observations of the
Ophiuchus cluster.
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MACS J1931 Steven Ehlert
Comparisons with Ophiuchus: Wide
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MACS J1931 Steven Ehlert
Comparisons with Ophiuchus: Zoom
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MACS J1931 Steven Ehlert
Conclusions
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The AGN jet power is sufficient to overcome radiative losses in the
cool core.
It appears that the AGN jets and large N-S oscillatory motion did
considerably more than simply suppress the cooling flow.
Some fraction of the original cool core now resides 30 kpc to the
north of the central AGN with evidence it was previously to the south
as well.
Most pronounced displacement of a cool core yet observed.
Evidence is mounting that cool cores in clusters can be seriously
disrupted or perhaps even outright destroyed by the physical processes
within.
Snowcluster March 31st 2010
MACS J1931 Steven Ehlert
Backup Slide: Temperature Profile
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Temperature profiles
projected and deprojected.
Clear discontinuities at 20
and 80 kpc.
Most likely due to N and S
offset ridges.
Still resolving continuum
structure.
MACS J1931 Steven Ehlert
Backup Slide: Density Profiles
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Electron density peaks off
center!
Contributions from offset
bright regions responsible
for this offset.
Still need to take ridges
into account in the
azimuthally averaged
profiles.
MACS J1931 Steven Ehlert