High-spectral-resolution Observations of the [S II] Emission-line Doublet in the Filamentary Nebula Surrounding NGC 1275

Abstract

We analyze new high-spectral resolution SITELLE observations (R = $\lambda /\Delta \lambda$ = 7000) of the filamentary nebula surrounding NGC 1275, central galaxy of the Perseus cluster. We present here analysis of the \sii$\lambda 6716$ and \sii$\lambda 6731$ emission line doublet, using its ratio to determine the electron density of the optically emitting filaments. We compare these measurements with electron densities derived from deep Chandra X-ray observations of the intra-cluster medium (ICM) to determine if any correlations in density can be found. We report the detection of a clear dichotomy between the outer filaments, displaying on average lower \sii\text{ }emission line ratio of $\sim 1.1$ and the inner filaments displaying higher ratios of $\sim 1.3$. These results indicate that most of the gaseous filaments lie close to the low-density threshold for the density measurement of $\sim 10^2{\text{ cm}}^{-3}$. Using radial profiles, we find that the inner filaments have a roughly constant density, whereas the ICM density decreases with radius. In the outer filaments, we observe hints of local connections between the densities of the ICM and optical filaments, but no clear correlation seems to be observed overall. We also combined these density measurements with cold molecular CO gas observations to derive a relationship between temperature, density and pressure for the multiphase environment surrounding NGC 1275. Finally, we investigated potential models to explain the observed density measurements and explored similar studies of filamentary nebula around other central galaxies of cool-core galaxy clusters.

22 pages, 7 figures, published in ApJ

References in corpus (20)

• Array Programming with NumPy
• Turbulent Heating in Galaxy Clusters Brightest in X-rays
• On the prevalence of radio-loud AGN in brightest cluster galaxies: implications for AGN heating of cooling flows
• Magnetic support of the optical emission line filaments in NGC 1275
• A Very Deep Chandra Observation of the Galaxy Group NGC 5813: AGN Shocks, Feedback, and Outburst History
• Cooling Time, Freefall Time, and Precipitation in the Cores of ACCEPT Galaxy Clusters
• Conduction and the Star-Formation Threshold in Brightest Cluster Galaxies
• Galaxy cluster mass profiles
• Optical IFU Observations of the Brightest Cluster Galaxy NGC 4696: The Case for a Minor Merger and Shock-excited Filaments
• The Weak Shock in the Core of the Perseus Cluster
• Hidden Cooling Flows in Clusters of Galaxies
• Machine Learning Approach to Integral Field Unit Spectroscopy Observations: I. HII Region Kinematics
• Radio jet-ISM interaction and positive radio-mechanical feedback in Abell 1795
• H$\alpha$-X-ray Surface Brightness Correlation for Filaments in Cooling Flow Clusters
• The VLT-MUSE and ALMA view of the MACS 1931.8-2635 brightest cluster galaxy
• High-Spectral Resolution Observations of the Optical Filamentary Nebula in NGC 1275
• A Machine Learning Approach to Integral Field Unit Spectroscopy Observations: II. HII Region LineRatios
• Inquiring into the nature of the Abell 2667 Brightest Cluster Galaxy: physical properties from MUSE
• A Novel Machine Learning Approach to Disentangle Multi-Temperature Regions in Galaxy Clusters
• Discovery of inverse-Compton X-ray emission and estimate of the volume-averaged magnetic field in a galaxy group