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MOSFIRE and LDSS3
Spectroscopy for an [OII] Blob
at z=1.18:
Gas Outflow and Energy
Source
Yuichi Harikane (The University of Tokyo)
Masami Ouchi, Suraphong Yuma, Michael Rauch,
Kimihiko Nakajima, Yoshiaki Ono
arXiv: 1406.7052
Accepted for publication in ApJ
Outline
• Introduction to galactic outflows and
[OII]Blobs
• Describing our target: [OII]Blob 10
• Observations
• Results
• Discussions
Galactic Outflow is Important !
• Galactic outflows powered by starformation activities and/or AGNs have
been reported.
Galactic Outflow is Important !
• Galactic outflows powered by starformation activities and/or AGNs have
been reported.
NOAO
Galactic Outflow is Important !
• Galactic outflows powered by starformation activities and/or AGNs have
been reported.
• Galactic outflows play a significant role in
galaxy formation and evolution.
– Chemical enrichment of IGM
– Regulating star formation
Galactic Outflow is Important !
• Galactic outflows powered by starformation activities or AGNs have been
reported.
+ SN and AGN
• Galactic outflows
play a significant role in
feedback
galaxy formation and evolution.
– Chemical enrichment of IGM
– Regulating
star
formation
Courtesy: Darren
Croton
Outflow Regulates Star Formation !
[OII]Blobs Have Galactic Outflows
• [OII]Blobs are galaxies with strong and
spatially extended [OII] emission beyond
their stellar components.
• Extended metal emission → strong outflow
• Yuma+13 find 12 [OII]Blobs at z~1.2 using
a Subaru large-area narrowband survey.
[OII]Blob1
Having an AGN
Blueshifted FeII2587 absorption
Outflow velocity is ~500 km/s
[OII] emission
Stellar componet
FeII absorption
~500 km/s
Yuma+13
[OII]Blob4
Blueshifted MgII doublet absorption
Outflow velocity is ~200 km/s
[OII] emission
Stellar componet
Yuma+13
[OII]Blobs Have Galactic Outflows
• [OII]Blobs are galaxies with strong and
spatially extended [OII] emission beyond
their stellar component.
• Extended metal emission → strong outflow
• Yuma+13 find 12 [OII]Blobs at z~1.2.
• [OII]Blobs are expected to have outflows.
Our Target: [OII]Blob 10
• One of the highest SSFR.
• No signature of AGN in the available data.
[OII] emission
Stellar componet
Harikane+14
• The aims of our study is …
– To check whether an outflow is occuring.
– To check the presence of an AGN
Observations
• Keck/MOSFIRE, Y-band (9800-11000Å), 2.4h
– Hβ4861, [OIII]4959,5007
– To check the presence of AGN
• Magellan/LDSS3, VPH-blue (4800-6600Å),
2.5h
– Metal absorption lines.
– To check whether [OII]Blob10 has an outflow
• Magellan/LDSS3, VPH-red (6700-8600Å),
0.5h
– [OII]3726,3729
Results: MOSFIRE
• Hβ, [OIII] doublet lines are detected with
high significance levels.
• Systemic redshift is z=1.1800±0.0002
• These lines appear to have two
Harikane+14
components.
Results: LDSS3 with VPH-blue
• Blueshifted FeII2587 and MgII2796,2804
absorption lines are identified with 2.7 and
5.5 σ levels, respectively.
Harikane+14
80 km/s
260 km/s
Results: LDSS3 with VPH-red
• [OII]3726,3729 emission lines are
detected with high significance level.
• The two components of each doublet line
are not resolved. R~1710 (cf. R~3390 in
MOSFIRE spectrum)
[OII]Blob 10 Has an Outflow!
• Blueshifted absorption lines indicate gas
outflow.
• The outflow velocity is 80-260 km/s.
Comparable !
• Escape velocity is 250±140 km/s.
– Estimated under the assumption of a singular
isothermal halo potential.
• Some fraction of outflowing gas would
escape from [OII]Blob 10 and the starformation activity could be suppressed.
Does [OII]Blob 10 Have an AGN?
Does [OII]Blob 10 Have an AGN?
It is likely that [OII]Blob 10 is a composite of
an AGN and star-forming regions.
Implications of Two Components.
• Two strong star-forming regions.
• A galaxy merger.
• A combination of a galaxy and an outflow
knot.
None of these three possibilities can be
conclusively ruled out given current results.
Summary
• We present the Keck/MOSFIRE and
Magellan/LDSS3 spectrosopy for [OII]Blob
10.
• [OII]Blob 10 has an outflow whose velocity
is 80-260 km/s.
• This outflow velocity is comparable to the
escape velocity, implying that the some
fraction of outflowing gas would escape.
• [OII]Blob 10 is likely to be a composite of
an AGN and star-forming regions.