Collisional heating as the origin of filament emission in galaxy clusters

Ferland, Gary J.; Fabian, A. C.; Hatch, N. A.; Johnstone, R. M.; Porter, R. L.; Hoof, P. A. M. van; Williams, R. J. R.

doi:10.1111/j.1365-2966.2008.14153.x

Cited by 152 publications

(232 citation statements)

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“…The required heating rates per particle due to dissipation and/or cosmic ray induced ionisation found by Ferland et al (2009) are several orders of magnitude higher than those in the nearest Milky Way giant molecular clouds, and the required thermal pressures identified by Ferland et al (2009) (see also Sanders et al 2004;Sanders & Fabian 2007) are about an order of magnitude higher than those of the envelopes of dense cores associated with low mass star formation. Though the heating and ionisation rates in the cold molecular regions of the NGC 1275 filaments may be lower than those in the corresponding optical emission regions, they still may greatly exceed those relevant to the nearby Milky Way dense cores.…”

Section: Introductionmentioning

confidence: 91%

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Molecular tracers of filamentary CO emission regions surrounding the central galaxies of clusters

Bayet

Hartquist²,

Viti

et al. 2010

A&A

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Context. Optical emission is detected from filaments around the central galaxies of clusters of galaxies. These filaments have lengths of tens of kiloparsecs. The emission is possibly due to heating caused by the dissipation of mechanical energy and by cosmic ray induced ionisation. CO millimeter and submillimeter line emissions as well as H 2 infrared emission originating in such filaments surrounding NGC 1275, the central galaxy of the Perseus cluster, have been detected. Aims. Our aim is to identify those molecular species, other than CO, that may emit detectable millimeter and submillimeter line features arising in these filaments, and to determine which of those species will produce emissions that might serve as diagnostics of the dissipation and cosmic ray induced ionisation. Methods. The time-dependent UCL photon-dominated region modelling code was used in the construction of steady-state models of molecular filamentary emission regions at appropriate pressures, for a range of dissipation and cosmic ray induced ionisation rates and incident radiation fields. Results. HCO + and C 2 H emissions will potentially provide information about the cosmic ray induced ionisation rates in the filaments. HCN and, in particular, CN are species with millimeter and submillimeter lines that remain abundant in the warmest regions containing molecules. Conclusions. Detections of the galaxy cluster filaments in HCO + , C 2 H, and CN emissions and further detections of them in HCN emissions would provide significant constraints on the dissipation and cosmic ray induced ionisation rates.

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Section: Introductionmentioning

confidence: 91%

“…The additional heating mechanism, is here -following Ferland et al (2009) -assumed to be dissipation. We incorporate it by adding a heat source term, H, to the equation of thermal balance.…”

Section: The Modelsmentioning

confidence: 99%

Molecular tracers of filamentary CO emission regions surrounding the central galaxies of clusters

Bayet

Hartquist²,

Viti

et al. 2010

A&A

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“…Ferland, Fabian & Johnstone 1994;Ferland et al 2009). Dust grains are sputtered rapidly (< 1 Myr) in the X-ray atmosphere (Draine & Salpeter 1979;Dwek & Arendt 1992) so cooling X-ray gas is likely dust-free.…”

Section: Forming Molecular Gas In Extended Filamentsmentioning

confidence: 99%

ALMA observations of cold molecular gas filaments trailing rising radio bubbles in PKS 0745−191

Russell

McNamara

Fabian

et al. 2016

Mon. Not. R. Astron. Soc.

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105

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We present ALMA observations of the CO(1-0) and CO(3-2) line emission tracing filaments of cold molecular gas in the central galaxy of the cluster PKS 0745-191. The total molecular gas mass of 4.6±0.3×10 9 M , assuming a Galactic X CO factor, is divided roughly equally between three filaments each extending radially 3 − 5 kpc from the galaxy centre. The emission peak is located in the SE filament ∼ 1 arcsec (2 kpc) from the nucleus. The velocities of the molecular clouds in the filaments are low, lying within ±100 km s −1 of the galaxy's systemic velocity. Their FWHMs are less than 150 km s −1 , which is significantly below the stellar velocity dispersion. Although the molecular mass of each filament is comparable to a rich spiral galaxy, such low velocities show that the filaments are transient and the clouds would disperse on < 10 7 yr timescales unless supported, likely by the indirect effect of magnetic fields. The velocity structure is inconsistent with a merger origin or gravitational free-fall of cooling gas in this massive central galaxy. If the molecular clouds originated in gas cooling even a few kpc from their current locations their velocities would exceed those observed. Instead, the projection of the N and SE filaments underneath X-ray cavities suggests they formed in the updraft behind bubbles buoyantly rising through the cluster atmosphere. Direct uplift of the dense gas by the radio bubbles appears to require an implausibly high coupling efficiency. The filaments are coincident with low temperature X-ray gas, bright optical line emission and dust lanes indicating that the molecular gas could have formed from lifted warmer gas that cooled in situ.

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“…O'Dea et al 2010;McDonald et al 2011b), we reiterate that another heat source (acting either alone or in concert with the young stars) is needed (e.g. Voit & Donahue 1997;Ferland et al 2009;Fabian et al 2011a;Oonk et al 2011;Johnstone et al 2012;Mittal et al 2012;Canning et al 2015).…”

Section: Comparison Of Fuv Lyα and Hα Morphologymentioning

confidence: 99%

“…The ionization states of the nebulae have been a mystery for three decades, and debate continues over the roles played by stellar photoionization, shocks, thermal conduction, mixing, and cosmic ray heating (e.g. Voit & Donahue 1997;Ferland et al 2009;Sparks et al 2009Sparks et al , 2012McDonald et al 2010;O'Dea et al 2010;Fabian et al 2011b;McDonald, Veilleux & Rupke 2011a;Mittal et al 2011;Oonk et al 2011;Tremblay 2011;Johnstone et al 2012). Whatever the case, there is strong evidence that young stars might play an important (although not exclusive) role in dictating the physics of both the warm (∼10 4 K) and cold (∼100 K) phases of the filaments (Voit & Donahue 1997;Canning et al 2010Canning et al , 2014McDonald et al 2010McDonald et al , 2011aO'Dea et al 2010).…”

mentioning

confidence: 99%

Far-ultraviolet morphology of star-forming filaments in cool core brightest cluster galaxies

Tremblay

O’Dea

Baum

et al. 2015

Mon. Not. R. Astron. Soc.

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We present a multiwavelength morphological analysis of star forming clouds and filaments in the central (< ∼ 50 kpc) regions of 16 low redshift (z < 0.3) cool core brightest cluster galaxies (BCGs). The sample spans decades-wide ranges of X-ray mass deposition and star formation rates as well as active galactic nucleus (AGN) mechanical power, encompassing both high and low extremes of the supposed intracluster medium (ICM) cooling and AGN heating feedback cycle. New Hubble Space Telescope (HST) imaging of far ultraviolet continuum emission from young (< ∼ 10 Myr), massive (> ∼ 5 M ) stars reveals filamentary and clumpy morphologies, which we quantify by means of structural indices. The FUV data are compared with X-ray, Lyα, narrowband Hα, broadband optical/IR, and radio maps, providing a high spatial resolution atlas of star formation locales relative to the ambient hot (∼ 10 7−8 K) and warm ionised (∼ 10 4 K) gas phases, as well as the old stellar population and radio-bright AGN outflows. Nearly half of the sample possesses kpc-scale filaments that, in projection, extend toward and around radio lobes and/or X-ray cavities. These filaments may have been uplifted by the propagating jet or buoyant X-ray bubble, or may have formed in situ by cloud collapse at the interface of a radio lobe or rapid cooling in a cavity's compressed shell. Many other extended filaments, however, show no such spatial correlation, and the dominant driver of their morphology remains unclear. We nevertheless show that the morphological diversity of nearly the entire FUV sample is reproduced by recent hydrodynamical simulations in which the AGN powers a self-regulating rain of thermally unstable star forming clouds that precipitate from the hot atmosphere. In this model, precipitation triggers where the cooling-to-freefall time ratio is t cool /t ff ∼ 10. This condition is roughly met at the maxmial projected FUV radius for more than half of our sample, and clustering about this ratio is stronger for sources with higher star formation rates.

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Collisional heating as the origin of filament emission in galaxy clusters

Cited by 152 publications

References 68 publications

Molecular tracers of filamentary CO emission regions surrounding the central galaxies of clusters

Molecular tracers of filamentary CO emission regions surrounding the central galaxies of clusters

ALMA observations of cold molecular gas filaments trailing rising radio bubbles in PKS 0745−191

Far-ultraviolet morphology of star-forming filaments in cool core brightest cluster galaxies

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