Advanced Projects
The original MAHALO-Subaru survey is completed! We are now advancing the project with the following extensive programs.
- Follow-up NIR spectroscopy (status: completed)
- ALMA sub-mm & radio observations (on-going)
- High redshift [OIII] emitter search (completed)
- Dual Hα and Lyα emitter search (completed)
- Deep follow-up imaging and spectroscopy (on-going)
- Spatially-resolved continuum and emission-line imaging (on-going)
- Line emitter and red sequence search with HSC (on-going)
- Multiple narrow-band and medium-band imaging with SWIMS (in preparation)
MAHALO-Spec
Follow-up NIR spectroscopy with MOIRCS/Subaru (PI: Kodama, T.)
Status: Completed
Publications: Hayashi, M. et al. 2011; Shimakawa, R. et al. 2014; 2015; see also the web release.
Background: It is expected that galaxies in dense environments have been intrinsically evolved earlier and/or subject to harassment from gravitational forces and gas pressures by surrounding objects. Such internal/external bias may change those chemical evolution histories.
Highlights (#17): We found enhanced gas-phase metallicities in low-mass star-forming galaxies in the proto-cluster regions (reds) relative to those in the general field (blue). This suggests that some sort of environmental effects many affect on the gas-phase metallicities such as early chemical enrichments and environmentally-biased inflow/outflow mechanisms.
On the other hand, we need further investigation at the moment, since contradictory results have been reported by several authors.
GRACIAS-ALMA (cluster and proto-clusters)
Galaxy Resolved Anatomy with CO Interferometry And Submm ALMA Observations (PI: Kodama, T.)
Status: On-going
Publications: Hayashi, M. et al. 2017; see also the web release.
TBD
MAHALO High Redshift Survey
[OIII] emitter search at z>3 with narrow-band imaging (PI: Kodama, T.)
Status: Completed
Publications: Suzuki, T. L. et al. 2015
TBD
Hα & Lyα Dual Emitter Search
Follow-up Lyα narrow-band imaging towards a protocluster and fields at z=2.53 (PI: Shimakawa, R.)
Status: Completed
Publications: Shimakawa, R. et al. 2017a,2017b
Background: Lyα emitters are commonly used in high-z galaxy surveys, however, the sampling effects of Lyα selection is still controversial. To test this effect from the aspects of environmental dependence, we carried out dual Hα and Lyα emitter search towards the densest star-forming proto-cluster to date, USS 1558–003 at z=2.53, with a new pair narrow-band filter for Lyα and Hα lines.
Highlights (#23): Wide FoV of the Suprime-Cam (32’×27’) finds the large-scale structures of Lyα emitters (crosses) across a ~50 Mpc (left panel) in which USS1558 cluster traced by the Hα emitters is embedded (black circles). However, there are surprisingly few Lyα emitters (green) in local over- densities (right panel). Star-forming galaxies in dense groups have three times lower escape fractions of Lyα photons than those in intergroup regions. These trends suggest the further depletion of Lyα emission along our line by more intervening cool CGM/IGM and/or dust surrounding the densest regions in the proto-cluster.
MAHALO-Deep Cluster Survey
MAHALO-Subaru, Deep Follow-up Line Imaging (PI: Kodama, T.)
Status: To be completed
Publications: Hayashi, M. et al. 2016; Shimakawa, R. et al. 2018a; 2018b
Background: Our past MAHALO-Subaru observations succeeded in mapping star-formation associated with high-z proto-cluster regions. We now seek further deep surveys for two richest proto-clusters (PKS 1138–262 & USS 1558–003) to accumulate fainter sources. This not only improves statistics but also allows the derivation of Hα and stellar luminosity functions.
Highlights (#28): Deep Hα line imaging succeeded in identifying >100 Hα-emitting members associated with the densest proto-cluster region. In its fragmented substructure, the dense groups host the larger number of massive galaxies than the intergroup regions (right figure), indicating that the densest parts in young proto-clusters would be the sweet spots to build massive red sequence galaxies seen in the today's clusters of galaxies.
MAHALO-Deep Field Survey
MAHALO-Subaru, Deep Follow-up Line Imaging (PI: Kodama, T.)
Status: On-going
Background: We have focused on massive galaxies that are thought to be ancestors of even massive quiescent systems in the local Universe, not the building blocks of today’s L*-type galaxies. Deep follow-up imaging can extend our science more globally, which provide less-mass emitter samples and more heavily-obscured Hα sources.
MAHALO Deep Spectroscopy
Deep follow-up NIR spectroscopy with MOSFIRE on the Keck Telescope (PI: Kodama, T.)
Status: On-going
TBD
GANBA-Subaru
Galaxy Anatomy with Narrow-Band AO-imaging with Subaru (PI: Minowa, Y. and Koyama, Y.)
Status: On-going
Publications: Minowa, Y. et al. 2018
TBD
HSC-HSC
Hybrid Search for Clusters with HSC (PI: Kodama, T.)
Status: On-going
Publications: Koyama, Y. et al. 2018
TBD
SWIMS-18
Super multi narrow-band and medium-band imaging survey (PI: Kodama, T.)
Status: In Preparation
TBD