Emission-Line Properties of the Optical Filaments of NGC 1275

Abstract

Extended nebular filaments are seen at optical wavelengths in NGC 1275, the central galaxy in the Perseus cluster. The agents responsible for the excitation of these filaments remain poorly understood. In this paper we investigate possible mechanisms for powering the filaments, using measurements from an extensive spectroscopic data set acquired at the Lick Observatory 3-m Shane telescope. The results show that the filaments are in an extremely low ionization and excitation state. The high signal-to-noise ratio of the spectra allows us to measure or place sensitive upper limits on weak but important diagnostic lines. We compare the observed line intensity ratios to the predictions of various ionization models, including photoionization by an active galactic nucleus, shock heating, stellar photoionization, and photoionization by the intracluster medium. We also investigate possible roles for cluster extreme-ultraviolet emission, and filtering of cluster soft X-ray emission by an ionized screen, in the energetics of the filaments. None of these mechanisms provides an entirely satisfactory explanation for the physical state of the nebulae. Heating and ionization by reconnection of the intracluster magnetic field remains a potentially viable alternative, which merits further investigation through Faraday rotation studies.

Accepted for publication in ApJ

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Cited by in corpus (28)

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• The relationship between the optical Halpha filaments and the X-ray emission in the core of the Perseus cluster
• On the origin and excitation of the extended nebula surrounding NGC 1275
• Stochastic Acceleration of ${}^3$He and ${}^4$He in Solar Flares by Parallel Propagating Plasma Waves: General Results
• Optical Spectroscopy of Halpha Filaments in Cool Core Clusters: Kinematics, Reddening, and Sources of Ionization
• Cosmic Chronometers: Constraining the Equation of State of Dark Energy. II. A Spectroscopic Catalog of Red Galaxies in Galaxy Clusters
• Kinematics and Excitation of the Molecular Hydrogen Accretion Disc in NGC 1275
• Discovery of atomic and molecular mid infra-red emission lines in off-nuclear regions of NGC 1275 and NGC 4696 with the Spitzer Space Telescope
• Ionized nebulae surrounding brightest cluster galaxies
• Optical IFU Observations of the Brightest Cluster Galaxy NGC 4696: The Case for a Minor Merger and Shock-excited Filaments
• Stellar populations in NGC 5128 with the VLT: evidence for recent star formation
• SDSSJ092712.65+294344.0: NGC 1275 at z=0.7?
• Cold filaments in galaxy clusters: effects of heat conduction
• Discovery of CIV Emission Filaments in M87
• Feedback in the cores of clusters Abell 3581, 2A 0335+096, and Sersic 159-03
• Central galaxy growth and feedback in the most massive nearby cool core cluster
• A deep spectroscopic study of the filamentary nebulosity in NGC4696, the brightest cluster galaxy in the Centaurus cluster
• Cooling of X-ray Emitting Gas by Heat Conduction in the Center of Cooling Flow Clusters
• Multiple Radial Cool Molecular Filaments in NGC 1275
• Unravelling the enigmatic ISM conditions in Minkowski's Object
• Powering of H$\alpha$ filaments by cosmic rays
• Detection of optical coronal emission from 10^6 K gas in the core of the Centaurus cluster
• Collisional excitation of [C II], [O I] and CO in Massive Galaxies
• Polarization Diagnostics for Cool Core Cluster Emission Lines
• Heating by Acoustic Waves of Multiphase Media
• High-spectral-resolution Observations of the [S II] Emission-line Doublet in the Filamentary Nebula Surrounding NGC 1275