The Energy Source of the Filaments Around the Giant Galaxy NGC 1275

The brightest galaxy in the nearby Perseus cluster, NGC 1275, is surrounded by a network of filaments. These were first observed through their Hα emission but are now known to have a large molecular component with a total mass approaching 10 11 Mof gas. The filaments are embedded in hot intracluster gas and stretch over 80 kpc. They have an unusually low excitation spectrum which is well modelled by collisional heating and ionization by secondary electrons. Here we note that the surface radiative flux from the outer filaments is close to the energy flux impacting on them from particles in the hot gas. We propose that the secondary electrons within the cold filaments, which excite the observed submillimetre through ultraviolet emission, are due to the hot surrounding gas efficiently penetrating the cold gas through reconnection diffusion. Some of the soft X-ray emission seen from the filaments is then due to charge exchange, although this is insufficient to account for all the observed X-ray flux. The filaments are complex with multiphase gas. Interpenetration of hot and cold gases leads to the filaments growing in mass, at a rate of up to 100 Myr −1 . The lack of soft X-ray cooling emission in cool core clusters is then due to the non-radiative cooling of hot gas on mixing with cold gas around and within the central galaxy.

[1]  G. Kowal,et al.  Fast magnetic reconnection and energetic particle acceleration , 2010, 1003.2637.

[2]  A. Lazarian,et al.  Particle reacceleration by compressible turbulence in galaxy clusters: effects of a reduced mean free path , 2010, 1011.1198.

[3]  S. Okamura,et al.  A DOZEN NEW GALAXIES CAUGHT IN THE ACT: GAS STRIPPING AND EXTENDED EMISSION LINE REGIONS IN THE COMA CLUSTER , 2010, 1005.3874.

[4]  Cambridge,et al.  Star formation in the outer filaments of NGC 1275 , 2010, 1002.1056.

[5]  R. Davies,et al.  Astronomical Society of the Pacific Conference Series , 2010 .

[6]  R. Elsner,et al.  X-rays from Saturn: A study with XMM-Newton and Chandra , 2009, 0911.5283.

[7]  M. Donahue,et al.  SPECTACULAR X-RAY TAILS, INTRACLUSTER STAR FORMATION, AND ULXs IN A3627 , 2009, 0910.0853.

[8]  M. Donahue,et al.  DISCOVERY OF C iv EMISSION FILAMENTS IN M87 , 2009, 0909.2063.

[9]  G. Kowal,et al.  NUMERICAL TESTS OF FAST RECONNECTION IN WEAKLY STOCHASTIC MAGNETIC FIELDS , 2009, 0903.2052.

[10]  G. Ferland,et al.  Collisional heating as the origin of filament emission in galaxy clusters , 2008, 0810.5372.

[11]  R. Kelley,et al.  Studies of X-ray production following charge exchange recombination between highly charged ions and neutral atoms and molecules , 2008 .

[12]  C. Conselice,et al.  Magnetic support of the optical emission line filaments in NGC 1275 , 2008, Nature.

[13]  A. Edge,et al.  Cold gas in the Perseus cluster core: excitation of molecular gas in filaments , 2008, 0804.2113.

[14]  G. Ferland,et al.  The origin of molecular hydrogen emission in cooling‐flow filaments★ , 2008, 0802.2535.

[15]  A. Fabian,et al.  A deeper X‐ray study of the core of the Perseus galaxy cluster: the power of sound waves and the distribution of metals and cosmic rays , 2007, 0705.2712.

[16]  G. Ferland,et al.  Discovery of Atomic and Molecular Mid-Infrared Emission Lines in Off-Nuclear Regions of NGC 1275 and NGC 4696 with the Spitzer Space Telescope , 2007, astro-ph/0702431.

[17]  A. Lazarian.  Enhancement and Suppression of Heat Transfer by MHD Turbulence , 2006, astro-ph/0608045.

[18]  J. Bregman,et al.  O VI Observations of Galaxy Clusters: Evidence for Modest Cooling Flows , 2006, astro-ph/0602323.

[19]  C. Crawford,et al.  On the origin and excitation of the extended nebula surrounding NGC 1275 , 2005, astro-ph/0512331.

[20]  A. Lazarian,et al.  Production of the large scale superluminal ejections of the microquasar GRS 1915+105 by violent magnetic reconnection , 2005 .

[21]  A. Lazarian,et al.  Magnetic fields in the universe : from laboratory and stars to primordial structures, Angra dos Reis, Brazil, 28 November - 3 December 2004 , 2005 .

[22]  C. Crawford,et al.  Detections of molecular hydrogen in the outer filaments of NGC 1275 , 2004, astro-ph/0411446.

[23]  R. Lallement,et al.  On the contribution of charge-exchange induced X-ray emission in the ISM and ICM , 2004 .

[24]  J. Binney,et al.  Cold filaments in galaxy clusters: effects of heat conduction , 2004, astro-ph/0401106.

[25]  J. Brackbill,et al.  The Kelvin–Helmholtz instability, differential rotation, and three-dimensional, localized, magnetic reconnection , 2002 .

[26]  Durham,et al.  Exciting molecular hydrogen in the central galaxies of cooling flows , 2002, astro-ph/0206382.

[27]  Leiden,et al.  A survey of molecular hydrogen in the central galaxies of cooling flows , 2002, astro-ph/0206379.

[28]  A. Lazarian,et al.  Compressible sub-Alfvénic MHD turbulence in low-beta plasmas. , 2002, Physical review letters.

[29]  C. Crawford,et al.  The missing soft X-ray luminosity in cluster cooling flows , 2002 .

[30]  C. Conselice,et al.  On the Nature of the NGC 1275 System , 2001, astro-ph/0108019.

[31]  A. Edge.  The detection of molecular gas in the central galaxies of cooling flow clusters , 2001, astro-ph/0106225.

[32]  M. Bremer,et al.  Infrared spectra of cooling flow galaxies , 2000, astro-ph/0009418.

[33]  M. Donahue,et al.  Hubble Space Telescope Observations of Vibrationally Excited Molecular Hydrogen in Cluster Cooling Flow Nebulae , 2000, astro-ph/0007062.

[34]  A. Dalgarno,et al.  Electron Energy Deposition in a Gas Mixture of Atomic and Molecular Hydrogen and Helium , 1999 .

[35]  Institute for Astronomy,et al.  The ROSAT Brightest Cluster Sample — III. Optical spectra of the central cluster galaxies , 1999, astro-ph/9903057.

[36]  A. Lazarian,et al.  Reconnection in a Weakly Stochastic Field , 1998, astro-ph/9811037.

[37]  S. Shore,et al.  Production of Energy-dependent Time Delays in Impulsive Solar Flare Hard X-Ray Emission by Short-Duration Spectral Index Variations , 1998 .

[38]  Konrad Dennerl,et al.  X-ray Emissions from Comets Detected in the Röntgen X-ray Satellite All-Sky Survey , 1997 .

[39]  S. Sridhar,et al.  Toward a theory of interstellar turbulence. 2. Strong Alfvenic turbulence , 1994 .

[40]  C. Crawford,et al.  Emission-line nebulae around central cluster galaxies in cooling flows , 1992 .

[41]  H. Böhringer,et al.  Heat conduction boundary layers of condensed clumps in cooling flows , 1989 .

[42]  Patrick J. McCarthy,et al.  Dynamical, physical, and chemical properties of emission-line nebulae in cooling flows , 1989 .

[43]  A. Fabian,et al.  The optical spectra of central galaxies in southern clusters: evidence for star formation , 1987 .

[44]  L. Cowie,et al.  The evaporation of spherical clouds in a hot gas. I - Classical and saturated mass loss rates , 1977 .

[45]  R. Lynds.  IMPROVED PHOTOGRAPHS OF THE NGC 1275 PHENOMENON. , 1970 .

[46]  M. Tomasko,et al.  Heating of H i Regions by Energetic Particles , 1968 .

[47]  W. Baade,et al.  On the Identification of Radio Sources. , 1954 .