The Origins and Ionization Mechanisms of Warm Filaments in Cool Core Clusters Michael McDonald Postdoctoral Associate - MIT Kavli Institute In collaboration with: S. Veilleux (UMd), R. Mushotzky (UMd), D. Rupke (Rhodes), C. Reynolds (UMd)

Agenda 6/14/ Structure in Clusters and Groups of Galaxies in the Chandra Era

Introduction  The presence of warm, ionized gas has been noted in the cores of several cooling flow clusters to date. Typically radial filaments centered on the BCG Surface brightness is too high by orders of magnitude to be ICM cooling through 10 4 K. Unanswered questions: Where did the gas come from? What is the ionization source? 6/14/2015Structure in Clusters and Groups of Galaxies in the Chandra Era 3 Perseus A, Conselice et al. 2001

Motivation & Sample Selection  Potential sources of gas: Starburst/AGN wind Stripped from infalling, gas-rich galaxies X-ray cooling flow Buoyant radio bubbles 6/14/2015Structure in Clusters and Groups of Galaxies in the Chandra Era 4  Potential sources of heat: Cosmic ray ionization AGN Young stellar populations Conduction from ICM Ionization by ICM X-rays

A Multiwavelength Database 6/14/2015Structure in Clusters and Groups of Galaxies in the Chandra Era 5 ObservatoryObs TypeWavelengthSource/Ref CXOPhot+SpecX-rayArchive HSTPhotFar UVMcDonald+11b GALEXPhotNear UVArchive MMTFPhotHαMcDonald+10,11a, b MMTFPhot~ 6700 ÅMcDonald+10,11a, b MagellanSpec~ ÅMcDonald in prep. KeckSpec~ ÅMcDonald in prep. 2MASSPhotNear IRArchive SpitzerPhotNear-mid IRArchive HerschelPhot+SpecMid-far IRMcDonald in prep. CARMAPhot+SpecSub-mmMcDonald in prep. VLAPhot1.4 GHzArchive

6/14/2015Structure in Clusters and Groups of Galaxies in the Chandra Era 6 A Multiwavelength Database (Optical) (X-ray) (Ha)

RESULTS: X-ray – Ha Correlations 6/14/2015Structure in Clusters and Groups of Galaxies in the Chandra Era 7 L Hα kT (<100kpc) dM/dt spec R Hα (kpc) R cool (kpc) kT in /kT out n in /n out K in /K out t c,in /t c,out THE WARM, IONIZED GAS IS A BYPRODUCT OF THE COOLING ICM!

RESULTS : The Role of Environment 6/14/2015Structure in Clusters and Groups of Galaxies in the Chandra Era 8  We examine the frequency of Hα emission versus various quantities at R 2500 Weak trends with mass, temperature Stronger trends with gas fraction & entropy Hα emission seen in low-entropy systems with high gas mass fraction The presence of warm gas is more dependent on the core properties than the global properties. kT 2500 [keV]M 2500 [10 13 M  ] K 2500 [10 2 keV cm 2 ]f gas,2500 Fraction of Clusters w/ Hα Emission

RESULTS : Star-forming Filaments 6/14/2015Structure in Clusters and Groups of Galaxies in the Chandra Era 9  Ha emission is spatially correlated w/ clumpy FUV emission (HST)  Ha flux is correlated w/ FUV flux and is consistent w/ ongoing star formation  SFR is correlated w/ X-ray cooling rate * average efficiency of ~15% is consistent w/ Universal baryon fraction STARS ARE FORMING OUT OF THE COOLING ICM AND PHOTO- IONIZING THE COOLING GAS! SFE = SFR/(dM/dt) L Hα [erg/s] L FUV [erg/s/Hz]

Summary  Warm (10 4 K), Hα-emitting gas is a byproduct of the cooling intracluster medium McDonald et al. (2010) Hα mass is correlated with the X-ray cooling rate Warm gas only seen in clusters with cool cores Hα filaments live in regions cooling an order of magnitude faster than surrounding ICM  The presence of multiphase gas is only weakly dependent on the global mass/temperature of the cluster, and strongly dependent on entropy gas fraction McDonald et al. (2011a)  In ~ 2/3 of cases, the Hα filaments are star-formation-heated McDonald et al. (2011b) Strong correlation between FUV and Hα flux and morphology Mid-IR, UV and Hα-determined star formation rates are consistent with a conversion of 15% of the X-ray cooling flow into stars. 6/14/2015Structure in Clusters and Groups of Galaxies in the Chandra Era 10

A Sneak Peak…  McDonald et al. (2011; in prep) Combining long-slit spectroscopy from Keck & Magellan w/ Hα imaging to produce pseudo-2D spectra E.g., spatial distribution of velocity dispersion Extended, thin filaments have narrow emission lines Nuclei and “disturbed” filaments have significantly broader lines. 6/14/2015Structure in Clusters and Groups of Galaxies in the Chandra Era 11 σvσv

A Sneak Peak…  McDonald et al. (2011; in prep) E.g., spatial distribution of [N II]/Hα ratio Filaments with UV emission have low [N II]/Hα ratios Nuclei and systems without UV emission have [N II]/Hα ratios and UV/Hα ratios consistent with fast shocks 6/14/2015Structure in Clusters and Groups of Galaxies in the Chandra Era 12 [N II]/Hα