2003/01/07 by S. Ciroi, M. Contini, P. Rafanelli +1 · 1 citation
Physics and Astronomy · #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1051/0004-6361:20030008
published as Astron.Astrophys. 400 (2003) 859-870 · Accepted for publication in Astronomy & Astrophysics
arxiv created 2003/01/07 · openalex publication_date 2003/03/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We present recent results from spectroscopic data and modeling of the biconical ionized gas in the Seyfert-2 galaxy NGC 4388. A field of kpc centered on the nucleus has been observed by means of the modern technique of integral field spectroscopy. The analysis of more than two hundred spectra allowed to study the physical characteristics of the gas in the surroundings of the active nucleus. The South-West ionization cone, revealed by the [] λ5007/Hβ excitation map, shows high emission line ratios not completely supported by simple photoionization. Composite models which account for the combined effects of photoionization and shock show that such high []/Hβ line ratios are emitted by low density ( ) gas inside large ( pc) shocked clouds ( ) reached by a relatively low flux from the active nucleus. The data of the VEELR in the North-East cone by Yoshida et al. (2002) have been modeled. The results confirm that photoionization is the prevailing mechanism, but nontheless weak shocks are under way between colliding clouds with small (<1 pc) sizes and low densities , moving outward at relatively low velocities ( ).