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MOSFIRE and LDSS3 Spectroscopy for an [OII] Blob at z=1.18:Gas Outflow and Energy SourceYuichi Harikane (The University of Tokyo)Masami Ouchi, Suraphong Yuma, Michael Rauch, Kimihiko Nakajima, Yoshiaki OnoarXiv: 1406.7052 Accepted for publication in ApJThank you for your introduction.I am Yuichi Harikane and a first year graduate student at ICRR.Actually, this is my first time to give a presentation in English.And my presentation may be little bit poor.So if you have any questions, please feel free to ask me.

I will talk about our recent spectroscopic study of an oIIblob, OIIBlob10, which is a galaxy with spatially extended [OII] emission.The paper of this study was accepted one week ago.And we can see the paper in arXiv.1OutlineIntroduction to galactic outflows and [OII]BlobsDescribing our target: [OII]Blob 10ObservationsResultsDiscussionsThis is the outline of my talk.Firstly I introduce the galactic outflows and [OII]Blobs.I describe our target, OIIblob 10.Then I present our observations, results, and discussions.2Galactic Outflow is Important !Galactic outflows powered by star-formation activities and/or AGNs have been reported.OK, firstly, galactic outflow is important.Galactic outflow is a large-scale outflow occurred in a galaxy.These outflows are powered by star-formation activities and/or AGNsAnd recently these outflows are reported in many galaxies.3Galactic Outflow is Important !Galactic outflows powered by star-formation activities and/or AGNs have been reported.

NOAO4Galactic Outflow is Important !Galactic outflows powered by star-formation activities and/or AGNs have been reported.Galactic outflows play a significant role in galaxy formation and evolution.Chemical enrichment of IGMRegulating star formationOK, firstly, galactic outflow is important.Galactic outflow is a large-scale outflow occurred in a galaxy.These outflows are powered by star-formation activities and/or AGNsAnd recently these outflows are reported in many galaxies.In galaxy formation, these galactic outflows are expected to play a significant role.For example, IGM is probably chemically enriched by outflows.Also, outflows is thought to regulate star formation.This effect regulating star-formation activities is called a feedback process.5Galactic Outflow is Important !Galactic outflows powered by star-formation activities or AGNs have been reported.Galactic outflows play a significant role in galaxy formation and evolution.Chemical enrichment of IGMRegulating star formationOutflow Regulates Star Formation !

+ SN and AGN feedbackCourtesy: Darren CrotonIn this figure, x-axis is absolute magnitudes of galaxies, and y-axis is the number density of the galaxies having a given magnitude.The dots show the luminosity function of the 2dF galaxies.And this line represents the simulated luminosity function without feedback such as outflows of supernovae and AGNs.If we add the supernova and AGN feedback, the luminosity function changes like this.So outflow regulates starformation activities.And is important to explain the observational luminosity function,6[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.And OIIBlobs are expected to have outflows.OIIBlobs are galaxies which have strong and spatially extened [OII] emission beyond their stellar components.It is expected that their extended metal emission lines, OII emission lines, are made by outflows.And Yuma et al find 12 OIIBlobs at redshift around 1.2 using a Subaru large-area narrowband survey, 7[OII]Blob1Having an AGNBlueshifted FeII2587 absorptionOutflow velocity is ~500 km/s

Yuma+13[OII] emissionStellar componet~500 km/sFeII absorptionThis is OIIBlob1 which is identified by Yuma et al.The left image corresponds to the [OII] emission, and the right image corresponds to the stellar component.And the yellow contour show the isophotal area in [OII] emission image.As you can see, [OII] emission is spatially extended beyond its stellar component.OIIB1 is classified as a type-2 AGN. ([NeV] emission, broad [OII] line width, the ratio of mid-infrared to radio fluxes)And blueshifted FeII absorption line is identified (2.2 sigma).This blueshifted absorption indicates the outflow in OIIBlob1.And outflow velocity is about five hundred km/s.8[OII]Blob4Blueshifted MgII doublet absorptionOutflow velocity is ~200 km/s[OII] emissionStellar componet

Yuma+13OIIBlob4 also has outflow.Blueshifted MgII doublet absorption lines are detected.These absorption lines indicate the outflow.The outflow velocity is about 200 km/s, smaller than that of OIIB1.9[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.So Yuma et al studies OIIB1 and OIIB4, and they report that OIIB1 and OIIB4 have outflows.Therefore, OIIBlobs are expected to have outflows.But the fraction of OIIblobs having AGN is not unknown.So it is unclear whether the possible outflows of OIIBlobs are mainly powered by AGNs or not.10Our Target: [OII]Blob 10One of the highest SSFR.No signature of AGN in the available data.

The aims of our study is To check whether an outflow is occuring.To check the presence of an AGN

[OII] emissionStellar componetHarikane+14And our target is OIIBlob10, which is originally identified by Yuma et al.This is [OII] emission image, and this is stellar component image.{OIII]Blob10 has one of the highest Specific star formation rate.And no signature of AGN are found in the available data.So the aims of our study is to check whether an outflow is occuring and to check the presence of AGN in OIIB10 with deep optical and near-infrared spectroscopic data.11ObservationsKeck/MOSFIRE, Y-band (9800-11000), 2.4hH4861, [OIII]4959,5007To check the presence of AGN

Magellan/LDSS3, VPH-blue (4800-6600), 2.5hMetal absorption lines.To check whether [OII]Blob10 has an outflow

Magellan/LDSS3, VPH-red (6700-8600), 0.5h[OII]3726,3729We conducted observations using Keck/MOSFIRE and Magellan/LDSS3.We carried out Y-band spectroscopy.This observation targeted Hbeta and OIII emission lines, to check the presence of AGN.We also conducted optical spectroscopy using Magellan LDSS3.We use two configurations.One is with VPH-blue grism, which targeted metal absorption lines in order to check the presence of AGN.The other is with VPH-red grism, which targeted OII emission lines.12

Results: MOSFIREH, [OIII] doublet lines are detected with high significance levels.Systemic redshift is z=1.18000.0002These lines appear to have two components.Harikane+14This is the result of the MOSFIRE observation.Hbeta and OIII doublet lines are detected with high significance level.Please look the bottom figures.The x-axis wavelength and y axis is flux. (10 to the - eighteen)And this is Hbeta OIII4959, and OIII5007 emission lines.These lines appear to have two components.The velocity difference of these two components is 170+/-50 km/s.We define the average redshift of two components as the systemic redshift of OIIB10.13Results: LDSS3 with VPH-blue Blueshifted FeII2587 and MgII2796,2804 absorption lines are identified with 2.7 and 5.5 levels, respectively.

80 km/sHarikane+14

260 km/sThis is the results of LDSS3 with VPH-blue grism.As shown in figure, blueshifted FeII and MgII absorption lines are identified.And the velocity offset of these lines are 80 km/s and 260 km/s, respectively.14Results: 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)

This is the result of LDSS3 with VPH-red grism.OII emission lines are detected with high significance level.And two components of each doublet line are not resolved.This is because the resolution of LDSS3 is lower than that of MOSFIRE.15[OII]Blob 10 Has an Outflow!Blueshifted absorption lines indicate gas outflow.The outflow velocity is 80-260 km/s.

Escape velocity is 250140 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 star-formation activity could be suppressed.Comparable !Ok, firstly we discuss the outflow in OIIBlob10.Blueshifted FeII and MgII absorption lines indicate gas outflow.And outflow velocity is 80-260 km/s.We estimate escape velocity to be 250 km/s.We estimate this under the assumption of a singular isothermal halo potential,And this escape velocity is comparable to the outflow velocity.So, some fraction of the outflowing gas would escape from [OII]Blob10 and the star-formation activity could be suppressed.16

Estimating Escape Velocity

We assume singular isothermal halo truncated at r=rh. (rh/r=10-100)Relation between escape velocity vesc and circular velocity vc

Circular velocity is estimated from [OII] line width (Rix+97)17The difference of the velocitiesMgII absorption 26040 km/sFeII absortption 8050 km/s

There are three possibilities explaing this difference.Emission filling in MgII absorptionDifference in oscillator strengthsFeII absorption in foreground galaxyEmission filling would be occurred in MgII absorption.Because MgII transitions are resonantly trapped, the resonance emission fills the absorption near the systemic redshift.This emission filling shifts the centroid of MgII absorption.

The second possibility is the difference of oscillator strengths.The oscillator strength of MgII larger than that of FeII.So MgII is optically more thick than FeII in the low density gas.Low density gas is found far from galaxy,And the speed of the galactic wind increases with increasing galactrocentric radius.So the velocity offset of MgII, which is low-density trace, is larger than that of MgII.

The third possibility is FeII absorption in foreground galaxy. FeII absorption is made by foreground galaxy, not by outflow.But MgII absorption is made by outflow.

These three possibilities explain the difference of the velocity offsets in FeII and MgII absorption.

18Does [OII]Blob 10 Have an AGN?

Then, we discuss whether the OIIBlob10 has an AGN or not.This is the BPT diagram, which is widely used to investigate the presence of an AGN.The x-axis is the NII/Halpha flux ratio, and y-axis is OIII/Hbeta flux ratio.And blue dots represent pure-starforming galaxies, red dots represent composites of AGN and star-forming regions, and green represents AGNs.But we cannot plot OIIBlob10 in this BPT diagram, because the NII/Halpha ratio is not available.Instead of the BPT diagram, we use other three diagrams.Upper right is called blue diagram, and x-axis is OII/hbeta, instead of NII/Halpha.Blue, red, and green contours are same as the BPT diagram.OIIB10 is represented by circles.Filled and open circles correpond to the dust-corrected and uncorrected line ratios, respectively.In this diagrams, OIIB10 is in the composite region.Lower left panel shows the Mex diagram.The x-axis is the stellar mass.OIIBlob10 is in the composite region and the AGN region,Lower right panel shows the Cex diagram.The x-axis is U-B color.OIIBlob10 is located in the composite and pure star-forming regions.From these three diagrams,

19Does [OII]Blob 10 Have an AGN?

It is likely that [OII]Blob 10 is a composite of an AGN and star-forming regions.It is likely that OIIBlob10 is a composite of an AGN and star-forming regions.20Implications 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.Finally we discuss the implications of the two components in the Hbeta and OIII emission lines.The origin of these two components are unknown,But there are three possibilities.First is that two strong star-forming regions are in OIIBlob10.Rotation or infall of these two regions makes the two components.Second is that OIIblob10 is a merger system.Two components corresponding to two merging galaxies.Third is that the HII regions and outflow knot are responsible to the two components.If the outflow is beamed to us, the bluer component would be outflow knot.None of these three possibilities can be conclusively ruled out.21Outflow Rate and Mass Loading FactorMass outflow rate

We estimate N(H) using MgII doublet ratio.

Mass loading factorRelatively higher than mass loading factors of galaxies of Arribas+14 and Rupke+05.

22SummaryWe 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.23