Large scale triangulation: from Struve to Refsdal

Jaan Pelt

Tartu Observatory

Expanding the Universe,

Conference in Tartu 27-29 April 2011

Professor with students

First Republic

Uniküla-Rannaküla

baseline

Wilhelm Struve1816-1819Triangulation of Livonia

Simuna-Võivere baselineNorthern part of Struve’s Arc

Sharpest angles

Size/Baseline

112 10

tan( )S

x

Large scale triangulation

Parallax measurements

Wilhelm Struve1835-1836

611.65 10

tan( )S

x

α Aquilae (Tartu Pubs. III, 1822) 0".181 current 0".198

α Lyrae (1835-1836) 0".125±0.055 (1840 AN) 0".2613 ± 0".0254 current 0".123

Friedrich Georg Wilhelm Struve b. 1793 Altona, Hamburgd. 1864 St. Petersburg

Astrometric tradition lives on

Valeri MalyutoHIPPARCOS,GAIA

Indrek KolkaGAIA

S Andromedae (1885)

Karl Ernst Albrecht Hartwig (1851 — 1923)

From orbital speeds to Eq.1

0

20

, 1, 1

( ) ( .1)

GMv

r

GMw M r

r

v MEq

w r

1922,ApJ 55,406

Among other: Rector of Baltic University (1946-1948) - Hamburg

Ernst Julius Öpik 22. oktoober 1893 – 10. september 1985

And now to distance!20

20

2 220

20

( ) ,

( ) , triangle!!!sin( )

[ ]( ) , because ,

sin( ) 1

1sin( )( )

[ ]

ML

ML

v M

w rv M

w D

v D l L D

w D l

vD

l w

919.3 10

tan( )S

x

150''

Öpik 1921 785000 pcÖpik 1922 450000 pcHubble 1929 275000 pcCurrent 690000 pc

Refsdal’s method

6'' 1314.95 10

tan( )S

x

Sjur Refsdal December 30, 1935 – January 29, 2009

Quasars!

Sleeping beauty (said Virginia Trimble)

First gravitational lens system QSO 0957+561

1979Dennis Walsh, Bob Carswell, and Ray Weymann using the Kitt Peak National Observatory 2.1 meter telescope.

Vanderriest et al. 1989 415 20 days

Controversy of baseline

measurement(time delay)

Press et al. 1992 536 5 days

Pelt et al. 1994 (Hamburg) 415 or 536 days

Pelt et al. 1996 (Hamburg) 423 6 daysKundić et al. 1997 417 3 daysPelt et al. 1998 (Oslo) 416.3 1.7 days

Sjur Refsdal and Rudy Schild

2002, Soomaa, Estonia

Oslo, 1997-1998 Centre of Advanced Studies

How it does?

Meta surveys

Best single lens( B1608+656, Suyu et al): 70.6 3.1First lens system (QSO 0957+561, Fadely et al):

6.78.579.3

Canonical (Freedman): 73 2 4

Prediction

Full observable universe will be covered at log(S)=15.46 or in 2036

Weak and strong lensing

Mapping of near by dark matter haloes

Second stage

Dark matter mapping methods

• Millisecond pulsar timing, Shapiro delays (Siegel et al).

• Microlensing (magnification events)

• Large scale weak lensing studies

• Strong lensing, precise modeling

How this will be done?

• 3000-4000 strong lens systems

• 300-400 lensed supernovae

• Abundant weak lensing data base

• Hundreds of thousands of microlensing events

Just one example – LSST(Large Synoptic Survey Telescope)

Final stage uses already compiled maps

Collectingtime delays forfast and faraway events

Galaxy microlensing taken into account

Paths through the real space

Can be done for:

• Gravitational waves (LISA)

• Gamma ray burst

• Far away quasars

• Yet unknown violent fast, bright, violent events

Conclusions

• Hamburg-Estonia connections (not taking into account Bernhard Schmidt – who worked 1927-1935 in Hamburg Observatory).

• Keep the first result!

• 2036 – Mission completed!