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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 ➢ Counteracting cooling flows in nearby clusters. ➢ More extreme cooling rates in MACS 1931. ➢ Observations of MACS 1931 in X-ray, Optical, and Radio. ➢ What has happened to the cool core in MACS 1931? ➢ All figures and results preliminary! Snowcluster March 31st 2010 MACS J1931 Steven Ehlert ➢ X-ray: ➢ ➢ ➢ Stanford: Steve Allen, Aurora Simionescu, Norbert Werner, Evan Million, Glenn Morris Cambridge: Andrew Fabian, Jeremy Sanders, Robert Dunn Optical: ➢ ➢ ➢ Collaborators Stanford: Anja von der Linden, Patrick Kelly, Doug Applegate, Mark Allen University of Hawaii: Harald Ebeling Radio: ➢ University of New Mexico: Greg Taylor, Gianfranco Gentile Snowcluster March 31st 2010 MACS J1931 Steven Ehlert Suppressing Cooling Flows ➢ ➢ ➢ 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. Snowcluster March 31st 2010 MACS J1931 Steven Ehlert Feedback in Virgo ➢ Nominal cooling rate of 20 -1 M⊙ yr in Virgo balanced by M87. ➢ ➢ Snowcluster March 31st 2010 Clear filaments and shocks here. Lots more from Norbert following this talk! MACS J1931 Steven Ehlert Feedback in Perseus ➢ ➢ ➢ Snowcluster March 31st 2010 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 ➢ ➢ What happens in clusters that have even larger nominal cooling rates? Can AGN feedback supply enough energy to counteract the large radiative losses? ➢ Does a residual cooling flow exist? ➢ Can we observe smaller scale processes at work? ➢ 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 ➢ One of the brightest cooling cores in the sky: bolometric luminosity is ~1045 erg s-1 within 50 kpc of center. ➢ At a redshift of z=0.352. ➢ Large nominal cooling rate: ~1000 M⊙ yr-1. ➢ ➢ 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 ➢ Two Chandra observations with ~100 ks total clean exposure. ➢ Deep multiband optical imaging (BVRIz) with Subaru. ➢ 1.4 GHz VLA radio data (A configuration). Snowcluster March 31st 2010 MACS J1931 Steven Ehlert Chandra Imaging ➢ ➢ Snowcluster March 31st 2010 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 ➢ ➢ Snowcluster March 31st 2010 Isophote centroid is changing with distance. Orientation angle of major axis also changing. MACS J1931 Steven Ehlert Chandra Imaging: Residuals ➢ ➢ ➢ Snowcluster March 31st 2010 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 ➢ ➢ Snowcluster March 31st 2010 What structures exist around the central AGN? Zoom in on the box. MACS J1931 Steven Ehlert Chandra Imaging: Around the AGN ➢ Several regions of interest: ➢ ➢ ➢ ➢ Snowcluster March 31st 2010 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 ➢ Snowcluster March 31st 2010 High-frequency bandpass filter was applied to image to reveal small scale structures. MACS J1931 Steven Ehlert Temperature Structure ➢ ➢ ➢ ➢ Snowcluster March 31st 2010 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 ➢ ➢ Snowcluster March 31st 2010 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 ➢ Snowcluster March 31st 2010 Looking more carefully at the center of the cluster... MACS J1931 Steven Ehlert Temperature Structure: Around the AGN ➢ ➢ ➢ ➢ Snowcluster March 31st 2010 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 ➢ Snowcluster March 31st 2010 Corresponding entropy map for MACS 1931. MACS J1931 Steven Ehlert Entropy Structure: Zoom ➢ Snowcluster March 31st 2010 Zooming in to the central regions... MACS J1931 Steven Ehlert Entropy Structure: Around the AGN ➢ ➢ Snowcluster March 31st 2010 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 ➢ ➢ ➢ Snowcluster March 31st 2010 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 ➢ ➢ ➢ ➢ Snowcluster March 31st 2010 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 ➢ ➢ ➢ Two offset regions have different thermodynamics: ➢ North: kT=5.4, Z=0.53 ➢ South: kT=5.6, Z=0.17 Uncertainties: kT ~ 15-20%; Z ~ 0.1. Also measured spectroscopic cooling rate: ➢ ➢ Snowcluster March 31st 2010 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 ➢ ➢ ➢ ➢ Snowcluster March 31st 2010 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 ➢ ➢ ➢ ➢ Snowcluster March 31st 2010 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 ➢ ➢ ➢ Snowcluster March 31st 2010 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 ➢ ➢ ➢ ➢ Snowcluster March 31st 2010 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 ➢ ➢ Snowcluster March 31st 2010 Extended radio emission surrounding the AGN. Narrow angle tail galaxy to the south. MACS J1931 Steven Ehlert Investigating the AGN with VLA ➢ ➢ Snowcluster March 31st 2010 Unusual morphology around the AGN. Spatially coincident with X-ray cavities. MACS J1931 Steven Ehlert Calculating the Jet Power ➢ ➢ Snowcluster March 31st 2010 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 ➢ 4PV enthalpy of cavities in previous image is 6 x 1060 erg. ➢ This corresponds to a jet power of ~1046 erg s-1. ➢ Uncertainty in cavity volume puts uncertainty of 4PV & jet power at a factor of ~2-3. ➢ For comparison, the AGN luminosity is ~8 x 1043 erg s-1. ➢ This AGN is radiatively inefficient! ➢ 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 ➢ Bright offset region to the north has all of the properties of a typical cool core: ➢ High density/surface brightness. ➢ Low temperature/entropy, enriched metallicity. ➢ Appreciable spectroscopic cooling rate (~180 M⊙ yr-1). ➢ ➢ ➢ 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 ➢ X-ray and optical observations indicate oscillations of the cool core along the north-south direction: ➢ ➢ ➢ ➢ 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 ➢ Central AGN is undergoing a massive outburst! ➢ ➢ ➢ ➢ 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 ➢ ➢ ➢ ➢ ➢ 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. Snowcluster March 31st 2010 MACS J1931 Steven Ehlert Comparisons with Ophiuchus: Wide Snowcluster March 31st 2010 MACS J1931 Steven Ehlert Comparisons with Ophiuchus: Zoom Snowcluster March 31st 2010 MACS J1931 Steven Ehlert Conclusions ➢ ➢ ➢ ➢ ➢ 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 ➢ ➢ ➢ ➢ Snowcluster March 31st 2010 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 ➢ ➢ ➢ Snowcluster March 31st 2010 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