Yuji Shirasaki
National Astronomical Observatory of Japan

2010/10/13

EAMA8 @ Shanghai, China

1Virtual Observatory
 Infrastructure for efficient research environment
 International standard for data publication & access Sharing data worldwide, Maximize scientific return
Data ServiceSDSS

2MASS

SubaruHSTAnalysis Service…

Application

Web portal

2010/10/13

EAMA8 @ Shanghai, China

2

VO Science
VO enables for a researcher
1) to find a small particular data subset from alarge collection of catalog and observation data2) to retrieve and use large amount data inautomated way
VO science papers
 http://www.euro-vo.org/pub/fc/papers.html

43 papers More and more VO science papers are appearing
 However, most of them are type-1 science case

 We demonstrated type-2 science case2010/10/13

EAMA8 @ Shanghai, China

3

JVO portal
http://jvo.nao.ac.jp/portal
JVO portal

Not registered …

 10,551 Data Resources– 7,397 Catalogs– 208 Image Services– 84 Spectrum Services– …

 Reduced Subaru Data
– Suprime-Cam– HDS
2010/10/13

EAMA8 @ Shanghai, China

4

JVO Subaru archive Suprime-Cam data reduction system– Data archive and parallel computing system areconnected with a dedicated network (128Gps)– The whole data can be processed in two weeks(using 48 CPU cores) VO access as well as a dedicated GUI– Data retrieval is “programmable”– Possible to retrieve cutout image for specified

region– Don’t need to download all the data (~10TB), data

can be retrieved on demand
2010/10/13

EAMA8 @ Shanghai, China

5GUI for Suprime-Cam archive2010/10/13

EAMA8 @ Shanghai, China

6

“Early Science Result from the Japanese Virtual
Observatory: AGN and Galaxy Clustering
at z = 0.3 to 3.0”
Y.Shirasaki et al. 2010 submitted to PASJ (arXiv:0907.5380v2)

 Measurement of AGN-Galaxy cross-correlation– Fueling mechanism of AGN– Co-evolution of galaxy and black hole
– Use all the data of Suprime-Cam archive (nobody have done !) Existing works– Redshift measurement  3D cross-correlation– z < 0.6 : Good statistic using SDSS data
– z > 0.6 : Relatively poor stat. (several tens).
••••
2010/10/13

Hard to increase statistics:
Statistic at small scale (~1Mpc) is extremely poor
Affected by Cosmic Variance
Biased to red galaxy in the spectroscopic target selection
EAMA8 @ Shanghai, China

7

Dataset
AGN samples
 Veron QSO/AGN Catalog (12th ed) SDSS DR-5 QSO Catalog (4th ed)

Galaxy samples
 JVO Suprime-Cam Archive (B,V,R,I,i’,z’ band) UKIDSS DR-2 Catalog (K band) Deepest observation data was used for each AGN

Suprime-Cam
UKIDSS
Total
2010/10/13

EAMA8 @ Shanghai, China

4841325
1809
8

Search Suprime-Cam image around AGN

2010/10/13

EAMA8 @ Shanghai, China

9Search Result
 Only a part ofdata is displayed
 No way todownload all theimage at one
 Download
coordinates inCSV format
 Create a list of AGN which is observed withSuprime-Cam
2010/10/13

EAMA8 @ Shanghai, China

10

Automate using a script Download and analysis for ~12,000 AGNs
̶ hard or impossible to do by hand.

 Make a script (e.g. shell script)
̶ Create a catalog from retrieved image data …
̶ Execute this script for each AGN

̶ 12,000 AGNs  40 parallels. Completed in one day.

 Access to VO
̶ Used command line access tool.
̶ Convenient to repeat the same query by changing thequery condition.
2010/10/13

EAMA8 @ Shanghai, China

11

AGN redshift & absolute mag

B

Dz4z1

2010/10/13

z2z5z3

EAMA8 @ Shanghai, China

12

Analysis
 Projected correlation function : w(rp)z1-D
z=0.3~0.6
Dim AGNs (651)z4-Bz=1.3~1.8
Bright AGNs (142)r0 = 5±2 h-1Mpc
6r0 = 11±3 h-1Mpc
24600
12Transverse
comoving distance (Mpc)
Transverse
comoving distance (Mpc) 13
2010/10/13
EAMA8 @ Shanghai,China

Results8 : rms of correlation function at < 8 Mpc

Clustering increases as redshift

2010/10/13

EAMA8 @ Shanghai, China

14

Summary
 Complementary with existing study– Precise correlation function at small scale (~3 h-1Mpc)– Free from cosmic variance– Sensitive to dim and blue star-forming galaxy

 Effectiveness of “reduced” Subaru data archive– Especially Suprime-Cam has high utility value; can be usedin may other research fields– Make it possible to do a study not possible if begin fromreduction of raw data
 Skill of writing a script for automation– GUI-based application is not helpful for utilizing large

amount of data
– JVO will provide command line access tools as well as online service accessible from the tool.
2010/10/13

EAMA8 @ Shanghai, China

15