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eDIG-CHANGES. II. Project Design and Initial Results on NGC 3556

Authors :
Jiang-Tao Li
Li-Yuan Lu
Zhijie Qu
Robert A. Benjamin
Joel N. Bregman
Ralf-Jürgen Dettmar
Jayanne English
Taotao Fang
Judith A. Irwin
Yan Jiang
Hui Li
Guilin Liu
Paul Martini
Richard J. Rand
Yelena Stein
Andrew W. Strong
Carlos J. Vargas
Q. Daniel Wang
Jing Wang
Theresa Wiegert
Jianghui Xu
Yang Yang
Source :
The Astrophysical Journal, Vol 967, Iss 2, p 78 (2024)
Publication Year :
2024
Publisher :
IOP Publishing, 2024.

Abstract

The extraplanar diffuse ionized gas (eDIG) represents ionized gases traced by optical/UV lines beyond the stellar extent of galaxies. We herein introduce a novel multislit narrow-band spectroscopy method to conduct spatially resolved spectroscopy of the eDIG around a sample of nearby edge-on disk galaxies (eDIG-CHANGES). In this paper, we introduce the project design and major scientific goals, as well as a pilot study of NGC 3556 (M108). The eDIG is detected to a vertical extent of a few kiloparsecs above the disk, comparable to the X-ray and radio images. We do not see significant vertical variation of the [N ii ]/H α line ratio. A rough examination of the pressure balance between different circumgalactic medium phases indicates the magnetic field is in a rough pressure balance with the X-ray emitting hot gas and may play an important role in the global motion of both the eDIG and the hot gas in the lower halo. At the location of an Hubble Space Telescope/Cosmic Origins Spectrograph observed UV bright background active galactic nucleus ∼29 kpc from the center of NGC 3556, the magnetic pressure is much lower than that of the hot gas and the ionized gas traced by UV absorption lines, although the extrapolation of the pressure profiles may cause some biases in this comparison. By comparing the position–velocity diagrams of the optical and CO lines, we also find the dynamics of the two gas phases are consistent with each other, with no evidence of a global inflow/outflow and a maximum rotation velocity of ∼150 km s ^−1 .

Details

Language :
English
ISSN :
15384357
Volume :
967
Issue :
2
Database :
Directory of Open Access Journals
Journal :
The Astrophysical Journal
Publication Type :
Academic Journal
Accession number :
edsdoj.bbc0a9f0de6428f95552c808aadfb2a
Document Type :
article
Full Text :
https://doi.org/10.3847/1538-4357/ad3cd8