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The strong gravitationally lensed Herschel galaxy HLock01: optical spectroscopy reveals a close galaxy merger with evidence of inflowing gas

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journal contribution
posted on 2023-06-12, 08:49 authored by Rui Marques-Chaves, Ismael Perez-Fournon, Raphael Gavazzi, Paloma Martinez-Navajas, Dominik Riechers, Dimitra Rigopoulou, Seb OliverSeb Oliver, Alain Omont, Douglass Scott, Yiping Shu, Julie Wardlow
The submillimeter galaxy (SMG) HERMES J105751.1+573027 (hereafter HLock01) at z = 2.9574±0.0001 is one of the brightest gravitationally lensed sources discovered in the Herschel Multi-tiered Extragalactic Survey. Apart from the high flux densities in the far-infrared, it is also extremely bright in the rest-frame ultraviolet (UV), with a total apparent magnitude mUV ˜19.7 mag. We report here deep spectroscopic observations with the Gran Telescopio Canarias of the optically bright lensed images of HLock01. Our results suggest that HLock01 is a merger system composed of the Herschel-selected SMG and an optically bright Lyman break-like galaxy (LBG), separated by only 3.3 kpc in projection. While the SMG appears very massive (M* ˜ 5×10^11 M?), with a highly extinguished stellar component (AV ' 4.3), the LBG is a young, lower-mass (M* ˜ 1×10^10 M?), but still luminous (10×L * UV) satellite galaxy. Detailed analysis of the high signal-to-noise (S/N) rest-frame UV spectrum of the LBG shows complex kinematics of the gas, exhibiting both blueshifted and redshifted absorption components. While the blueshifted component is associated with strong galactic outflows from the massive stars in the LBG, as is common in most star-forming galaxies, the redshifted component may be associated with gas inflow seen along a favorable sightline to the LBG. We also find evidence of an extended gas reservoir around HLock01 at an impact parameter of 110 kpc, through the detection of C II ??1334 absorption in the red wing of a bright Lya emitter at z˜ 3.327. The data presented here highlight the power of gravitational lensing in high S/N studies to probe deeply into the physics of high-z star forming galaxies.

History

Publication status

  • Published

File Version

  • Published version

Journal

Astrophysical Journal

ISSN

0004-637X

Publisher

IOP Publishing

Issue

151

Volume

854

Page range

1-20

Department affiliated with

  • Physics and Astronomy Publications

Research groups affiliated with

  • Astronomy Centre Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2018-01-29

First Open Access (FOA) Date

2018-01-29

First Compliant Deposit (FCD) Date

2018-01-29

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