Open AccessDetections of molecular hydrogen in the outer filaments of NGC 1275
Author(s) -
Hatch N. A.,
Crawford C. S.,
Fabian A. C.,
Johnstone R. M.
Publication year - 2005
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2005.08787.x
Subject(s) - physics , intracluster medium , astrophysics , molecular cloud , galaxy , excited state , line (geometry) , excitation , nucleus , active galactic nucleus , cluster (spacecraft) , astronomy , spectral line , collisional excitation , galaxy cluster , atomic physics , stars , ionization , ion , quantum mechanics , geometry , mathematics , computer science , biology , programming language , microbiology and biotechnology
We present clear spectroscopic detections of molecular hydrogen in the outer filaments of the Hα nebula surrounding the central galaxy of the Perseus cluster, NGC 1275. This implies the presence of warm molecular gas clouds at projected distances up to 24 kpc from the nucleus of the host galaxy, embedded in the hot intracluster medium. The emission‐line intensity ratios reveal that the H 2 is predominately thermally excited with excitation temperatures of 1600–2200 K, suggesting a lack of pressure balance between the molecular component and its surrounding medium. Excitation by stellar ultraviolet or by the central active galactic nucleus is shown to be unlikely, while thermal excitation by X‐rays or conduction from the ICM or shocks are all possibilities. Evidence for a non‐thermal component is found in the spectra of some regions based on a low ortho‐to‐para ratio.