Program: GN-2022A-Q-221

Title:Mechanism behind co-existence of extreme outflows and starbursts in ULIRGs
PI:Xiaoyang Chen
Co-I(s): Masayuki Akiyama, Kohei Ichikawa, Yoshiki Toba, Toshihiro Kawaguchi, Hirofumi Noda, Issei Yamamura, Mitsuru Kokubo, Abdurrouf Abdurrouf, Klod Vijarnwannaluk

Abstract

Ultra-luminous IR galaxies (L_IR > 1E12 Lsun, ULIRGs) are thought to represent the rapidly growing phase of massive galaxies before quenching of their star formation by powerful AGN-driven outflows. In order to examine the statistical AGN and outflow properties of ULIRGs, we have constructed an AKARI 90 micron flux limited catalog of 1028 ULIRGs at z = 0.1-1.0. Five ULIRGs in the sample show extremely fast outflows (v_out > 1500 km/s), which are the most powerful outflows observed among ULIRGs/AGNs at z < 1. However, the star formation in the five ULIRGs are highly intense with SFR of 300-2000 Msun/yr, comparable to the SFR of high-z ULIRGs. The co-existence of the extremely fast outflows and high SFR is conflicting with the classical AGN feedback scenario. One possibility is that although the AGN-driven wind is powerful, it has not affected the entire star-forming region. In order to understand the interplay between the extreme outflows and starbursts, we propose to map the outflows and star-forming regions in the ULIRGs with IFU observations. The proposed observation is important to constrain the spatial extent of the strong outflows, and to further estimate the timescale and mass-loss rate of the AGN feedback effect.