<i>Herschel</i>observations of extended atomic gas in the core of the Perseus cluster

Mittal, R.; Oonk, J. B. R.; Ferland, Gary J.; Edge, A. C.; O’Dea, C. P.; Baum, Stefi A.; Whelan, J. T.; Johnstone, R. M.; Combes, F.; Salomé, P.; Fabian, A. C.; Tremblay, G. R.; Donahue, M.; Russell, H. R.

doi:10.1111/j.1365-2966.2012.21891.x

Cited by 49 publications

(55 citation statements)

References 104 publications

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“…Although radiative trapping, in particular, can contribute appreciably to exciting molecules at high optical depths (e.g., see Shirley 2015), in Galactic GMCs collisions with H 2 dominate the excitation of CO. Using Herschel, Mittal et al (2012) detected far-IR emission from dust in the filaments at the inner regions of NGC 1275. They infer two bulk (albeit highly uncertain) temperatures for this dust, one at about 30-40 K and the other at about 100 K. The cooler component has an inferred mass somewhat less than 10 7 M , and the warmer component somewhat less than 10 5 M .…”

Section: Radiative Excitationmentioning

confidence: 99%

The Role of Electron Excitation and Nature of Molecular Gas in Cluster Central Elliptical Galaxies

Lim

Dinh-V-Trung

Vrtilek³

et al. 2017

ApJ

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We present observations in CO(3-2) that, combined with previous observations in CO(2-1), constrain the physical properties of the filamentary molecular gas in the central ∼6.5 kpc of NGC 1275, the central giant elliptical galaxy of the Perseus cluster. We find this molecular gas to have a temperature 20 K and a density ∼10 2 -10 4 cm −3 , typically warmer and denser than the bulk of Giant Molecular Clouds (GMCs) in the Galaxy. Bathed in the harsh radiation and particle field of the surrounding intracluster X-ray gas, the molecular gas likely has a much higher ionization fraction than that of GMCs. For an ionization fraction of ∼10 −4 , similar to that of Galactic diffuse ( 250 cm −3 ) partially-molecular clouds that emit in HCN(1-0) and HCO + (1-0), we show that the same gas traced in CO can produce the previously reported emissions in HCN(3-2), HCO + (3-2), and CN(2-1) from NGC 1275; the dominant source of excitation for all the latter molecules is collisions with electrons. To prevent collapse, as evidenced by the lack of star formation in the molecular filaments, they must consist of thin strands that have crosssectional radii 0.2-2 pc if supported solely by thermal gas pressure; larger radii are permissible if turbulence or poloidal magnetic fields provide additional pressure support. We point out that the conditions required to relate CO luminosities to molecular gas masses in our Galaxy are unlikely to apply in cluster central elliptical galaxies. Rather than being virialized structures analogous to GMCs, we propose that the molecular gas in NGC 1275 comprises pressure-confined structures created by turbulent flows.

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Section: Radiative Excitationmentioning

confidence: 99%

The Role of Electron Excitation and Nature of Molecular Gas in Cluster Central Elliptical Galaxies

Lim

Dinh-V-Trung

Vrtilek³

et al. 2017

ApJ

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“…One mysterious feature is an extensive "web" of gaseous, emission line filaments, strongly emitting in Hα (Minkowski 1955;Lynds 1970). Observations of H2 and CO have shown a substantial mass of molecular gas exists in the core of NGC 1275 (Bridges & Irwin 1998;Donahue et al 2000;Edge et al 2002) and is also entrained in the filaments (Hatch et al 2005;Salomé et al 2006;Johnstone et al 2007;Salomé et al 2011;Lim et al 2012), and recent far infrared (FIR) observations with the Herschel space telescope are allowing us to probe the nature of this cold gas reservoir (Mittal et al 2012). The most promising mechanism for heating these multiphase filaments is supra-thermal particle heating from the surrounding hot X-ray ICM (Ferland et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Filamentary star formation in NGC 1275

Canning

Ryon

Gallagher

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We examine the star formation in the outer halo of NGC 1275, the central galaxy in the Perseus cluster (Abell 426), using far ultraviolet and optical images obtained with the Hubble Space Telescope. We have identified a population of very young, compact star clusters with typical ages of a few Myr. The star clusters are organized on multiple-kiloparsec scales. Many of these star clusters are associated with "streaks" of young stars, the combination of which has a cometary appearance. We perform photometry on the star clusters and diffuse stellar streaks, and fit their spectral energy distributions to obtain ages and masses. These young stellar populations appear to be normal in terms of their masses, luminosities and cluster formation efficiency; <10% of the young stellar mass is located in star clusters. Our data suggest star formation is associated with the evolution of some of the giant gas filaments in NGC 1275 that become gravitationally unstable on reaching and possibly stalling in the outer galaxy. The stellar streaks then could represent stars moving on ballistic orbits in the potential well of the galaxy cluster. We propose a model where star-forming filaments, switched on ∼50 Myr ago and are currently feeding the growth of the NGC 1275 stellar halo at a rate of ≈2-3 M yr −1 . This type of process may also build stellar halos and form isolated star clusters in the outskirts of youthful galaxies.

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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%

“…Eleven of these targets constitute the Herschel CC clusters Open Time Key Project sample of A. Edge and collaborators (Edge et al 2010a,b;Mittal et al 2011Mittal et al , 2012Rawle et al 2012;Tremblay et al 2012a,b;Hamer et al 2014), selected to span a wide range of both cooling flow and BCG physical properties. The remaining five targets are from the non-overlapping sample of O'Dea et al (2010), selected from the Quillen et al (2008) sample on the basis of elevated infrared-estimated SFRs.…”

Section: Sample Selectionmentioning

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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Herschelobservations of extended atomic gas in the core of the Perseus cluster

Cited by 49 publications

References 104 publications

The Role of Electron Excitation and Nature of Molecular Gas in Cluster Central Elliptical Galaxies

The Role of Electron Excitation and Nature of Molecular Gas in Cluster Central Elliptical Galaxies

Filamentary star formation in NGC 1275

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

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