1. in a Large-Scale Structure at z=3.1
Lyman alpha blobs
in a Large-Scale Structure at z=3.1
Yuichi Matsuda (Tohoku Univ. / NAO Japan)
collaborators
Toru Yamada (NAO Japan)
Tomoki Hayashino (Tohoku Univ.) et al.
Y. Matsuda et al., AJ, 2004, in press
T. Hayashino et al., AJ, 2004, in press
Thank you.
Good afternoon!!
I’m Yuichi Matsuda.
I’m gonna talk about Subaru observation of a protocluster at high redshift.

2. Outline The protocluster at z=3.1 in SSA22 is
one of the best field to study high-z galaxies
in high density region
The previous survey (9’ x 9’) Lyman alpha emitters
(Steidel et al. 2000) Lyman alpha blobs
Our NB survey (32’ x 24’) Lyman alpha emitters
(Hayashino et al. 2004) Lyman alpha blobs
(1) A belt-like structure of Lyman alpha emitters
(length ≥ 60 Mpc in comoving scale)
(2) The first large sample of Lyman alpha blobs
(size = kpc in physical scale)
The protocluster at z=3.1 in SSA22 is one of the best field to study high-z galaxies
in high density region
The previous narrow-band survey of this protocluster shows it has 70 Lyman alpha emitters and 2 gaint Lyman alpha blobs.
But the field of view is nine arcmin times nine arcmin.
So we can not know how big this protocluster is and how typical the 2 giant blobs are.
In order to answer those questions, we got much wider and much deeper narrow-band image of this protocluster.
As a result, we detected about three hundred Lyman alpha emitters and thirty five Lyman
alpha blobs.
The sky distribution of Lyman alpha emitters show a belt-like structure.
The length of this structure is more than 60 Mpc in comoving scale.
35 Lyman alpha blobs we detected are the first large sample of Lyman alpha blobs.
The size of the blobs is 30 to 200kpc in physical scale.
The first topic is a large scale structure of emission-line galaxies at high redshift.
The size of this structure is about 60 Mpc in comoving scale.
The next topic is 35 Lyman alpha blobs in this large scale structure.
The size of the Lyman alpha blobs is about 100 kpc in physical scale.

3. Our target field (Steidel et al. 1998, 2000)
The protocluster at z=3.1 in SSA22
　　　　　　 (Steidel et al. 1998, 2000)
Redshift distribution of
Lyman-break galaxies
z=3.1 peak
The SSA22 z=3.1 peak of
Lyman-break galaxies
has δρgal/ρgal = 5
in 16 x 16 x 37 Mpc N
First, I’m gonna talk about our target field, the protocluster at z=3.1 in SSA22.
This protocluster was discovered by Steidel et al. in 1998.
They found a large peak in redshift distribution of Lyman break galaxies in SSA22.
This peak is also the largest peak in their 17 survey fields.
The SSA22 z=3.1 peak is
the largest peak in their
17 survey fields of
Lyman-break galaxies at z~3
Redshift

4. Our target field (Steidel et al. 1998, 2000)
The protocluster at z=3.1 in SSA22
　　　　　　 (Steidel et al. 1998, 2000)
Steidel et al. (2000) got
a deep narrow-band image
of the protocluster.
16Mpc
They got a deep narrow-band image of this protocluster.
They found a lot of Lyman alpha emitters in this protocluster.
They found 70 Lyman alpha emitters.
16Mpc

5. Our target field (Steidel et al. 1998, 2000)
The protocluster at z=3.1 in SSA22
　　　　　　 (Steidel et al. 1998, 2000)
They also found
2 giant (~200kpc)
Lyman alpha blobs.
300kpc
Blob1 and Blob2 have Sub-mm sources. (Chapman et al. 2001)
SFR ~ 1000 Mo/yr
Formation of massive galaxies?
They also found 2 giant Lyman alpha blobs.
They called the blobs, blob1 and blob2.
The size of the blobs is about 200kpc in physical scale.
Blob1 and blob2 have sub-millimeter sources.
Star formation rate estimated from sub-millimeter flux is about one thousand
solar mass per year.
So the 2 giant blobs may be related to formation of massive galaxies.
Continuum Lyman alpha

6. Our observation We got 9 times wider and 0.4 mag deeper
narrow-band image of the SSA22 protocluster at z=3.1
Our field of view 32’ x 24’
Steidel et al. (2000) 9’ x 9’
Subaru 8m telescope
Suprime-Cam
Narrow-band filter
7.2 hour exposure!!
45Mpc
The field of view of narrow-band image by Steidel et al. is nine arcmin times nine arcmin.
How big is this protocluster?
How typical are the 2 giant blobs?
We need wider and deeper narrow-band image of this protocluster.
We used Subaru 8m telescope and the prime focus camera, Suprime-Cam.
We got 9 times wider and 0.4mag deeper image.
60Mpc

7. (1) Large scale structure at z=3.1
We found a belt-like structure of
~300 Lyman alpha emitters
(length ≥ 60 Mpc in comoving scale)
Our field of view 32’ x 24’
283 Lyman alpha emitters
Photometry
2” diameter aperture
Lyman alpha flux
> 2 x ergs/s/cm2
EWobs > 170A
45Mpc
Lyman alpha blobs
The first question is how big this protocluster is.
We detected about 300 Lyman alpha emitters.
This is the skymap of Lyman alpha emitters.
The region inside this red line is high density region of emitters.
We found a belt-like structure of high density region.
The length of this structure is more than 60 Mpc in comoving scale.
δρgal/ρgal ~ 2
60Mpc

8. (1) Large scale structure at z=3.1
Large filament of emitters
(length ≥ 60 Mpc & radius ~10Mpc)
56 spectroscopically confirmed Lyman alpha emitters at z=3.1
Subaru 8m telescope
FOCAS MOS
hour exposure!!
45Mpc
We got spectra of emitters in this belt-like structure.
We have no contamination in our sample of Lyman alpha emitters.
We found the belt-like structure is continuous large filament in 3 D space.
The radius of this filament is about 10 Mpc.
No contamination by
[OII] and [OIII] emitters
60Mpc

9. (2) Lyman alpha blobs We could resolved detail structures 300kpc
Green shows
Lyman alpha
The next question is how typical the 2 giant blobs are.
Our narrow-band image is very deep, so we could resolve detail structure of Blob1 and Blob2.
Can we get new Lyman alpha blobs?
200 kpc
Continuum Lyman alpha
Steidel et al. (2000) Our deep images

10. (2) Lyman alpha blobs We found 33 new Lyman alpha blobs
Lyman alpha emitters
35 Lyman alpha blobs
Photometry
isophotal aperture
Lyman alpha flux
> 7 x ergs/s/cm2
EWobs>80A
Size > 30 kpc
Lyman alpha blobs are
more concentrated!!
45Mpc
Blob1 and Blob2
Yes!!
We could find 33 new Lyman alpha blobs in our image.
We selected Lyman alpha blobs with the size more than 30 kpc in physical scale.
Here is sky map of Lyman alpha blobs and Lyman alpha emitters.
Lyman alpha blobs are more concentrated in the belt-like structure.
δρgal/ρgal ~2
60Mpc

11. (2) Lyman alpha blobs The first large sample of Lyman alpha blobs
35 Lyman alpha blobs have large varieties
Blob Blob2
Blob1 and Blob2 are the largest and the brightest in our 35 sample.
The 35 blobs have large varieties of size, surface brightness, and morphology.
This is the first large sample of Lyman alpha blobs.
The first large sample of
Lyman alpha blobs
200kpc

12. (2) Lyman alpha blobs Large varieties different origins?
(1) Photoionization by massive stars or by AGN
(in some cases … may be hidden by dust)
(2) Cooling radiation in collapsing halo (e.g. Haiman et al. 2000)
(early phase of galaxy formation)
(3) Galactic superwind (e.g. Taniguchi & Shioya 2000)
(late phase of intense star formation)
Plus, scattering..
The large varieties of blobs may show difference of their origins.
The simplest model is photoionization by massive stars or by AGN.
The second model is cooling radiation in collapsing halo.
The third model is galactic superwind.
Scattering must be important in all of the blobs.

13. (2) Lyman alpha blobs Choice of the continuum object:
Lyman alpha flux vs. UV continuum flux
Choice of the continuum object:
the nearest source to the Lyman alpha peak, or the known LBG
Blob1
Blob2
Lyman alpha Excess
Can we explain the origin of the blobs by photoionization?
We compared the Lyman alpha flux and UV continuum flux.
The green line shows expected Lyman alpha flux from their UV flux of massive stars.
Now we assume no dust and Salpeter IMF.
About 30% blobs show Lyman alpha excess.
So we can not explain the origin of Lyman alpha blobs by massive star photoionization.
Actually, we have good candidates of cooling radiation or galactic superwind.
14 / 35 blobs show
Lyman alpha Excess
to the massive star
photoionization
(no dust, Salpeter IMF).

14. (2) Lyman alpha blobs Galactic superwind? Conical structure 200kpc
For example, this blob has conical structure.
This structure may be evidence for galactic superwind.
Galactic superwind?
200kpc

15. (2) Lyman alpha blobs Galactic superwind? Cooling radiation? Blob1
Bubble-like structure
Galactic superwind?
(see also Ohyama et al. 2003) or
Cooling radiation?
Velocity structure is chaotic
(Bower et al. 2004)
Blob1 has bubble-like structure.
This may also be evidence for galactic superwind.
200kpc

16. (2) Lyman alpha blobs Cooling radiation from collapsing halo?
This blob does not have plausible continuum source.
We think this is a good candidate for cooling radiation from collapsing halo.
Diffuse nebulae &
No plausible continuum source
200kpc

17. Summary The protocluster at z=3.1 in SSA22 has
(1) Large filament of Lyman alpha emitters
(length ≥ 60 Mpc in comoving scale)
(2) 35 Lyman alpha blobs
( size = kpc in physical scale)
The first large sample of Lyman alpha blobs
More concentrated then emitters
Blob1 and Blob2 are the largest and the brightest blobs
1/3 has Lyman alpha excess to massive star photoionization
Good sample of forming galaxies
in high density region at high redshift
This is the summary of my talk.
Thank you.