ALMA Polariza,on Commissioning and Verifica,on Status

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1 ALMA Polariza,on Coissioning and erifica,on Status Kouichiro Nakanishi (Joint ALMA Observatory/NAOJ on behalf of ALMA Polariza,on Coissioning Tea H.Nagai (NAOJ, E.Foalont, S.Coder (JAO, R.Hills (Cabridge, G.Moellenbrock (NRAO, E.Chapillon,.- W.Tang (ASIAA,

2 ALMA Polariza,on: Goal High sensiovity and high angular resoluoon polarizaoon observaoon with both cononuu and line at illieter and sub- illieter wavebands Requireents easure linearly and circularly polarized fluxes down to 0.1% level of total flux deterine the posioon angle of linearly polarized flux beer than 6 degrees

3 ALMA Polariza,on: Status PolarizaOon observaoon capability was not opened at Cycle 0/1 Coissioning and syste/science verificaoon acovioes are going on We are close to roll out ALMA PolarizaOon, and it will be available in near future

4 Coissioning and erifica,on ``Polariza,on Coissioning Tea is being in charge of coissioning and verificaoon of this new capability JAO eber experts of polarizaoon observaoon fro ALMA partners (EA/NA/EU

5 ALMA Polariza,on: Syste pol SIS ixer Ap Ortho ode transducer or Wire grid pol SIS ixer Ap Ap *n = I Q cos(2 U sin( 2 Correlator pol SIS ixer output fro ideal interferoeter *n = I Q cos(2 U sin( 2 *n = Q sin( 2 U cos(2 i *n = Q sin( 2 U cos(2 i Ortho ode transducer or Wire grid pol SIS ixer Ap Observe two orthogonal linear polarizaoon signal - > four types of cross- correlaoon output - > four Stokes paraeters

6 i U Q D D I i U Q D D I U Q I U Q I n n n n n n = = = = cos(2 sin(2 ( cos(2 sin(2 ( sin(2 cos(2 sin(2 cos(2 * * * * * * Instruental polariza,on D D = = Instruental PolarizaOons (D ters: fracoon of the input signal voltage in one polarizaoon that leaks into the output of the other polarizaoon. Typical agnitude of instruental polarizaoon is an order of a few ~ several %, which is coparable to or larger than astronoical source polarizaoons!

7 Instruental polariza,on The polarizaoon coissioning tea has been invesogaong instruental polarizaoon properoes stability, frequency dependencies, and changes within a field of view (f.o.v. Instruental polarizaoons are quite stable they are likely to be well calibrated at a center of f.o.v. they do not change draaocally within a fracoon of f.o.v.

8 Instruental polariza,on 4 GHz 4hrs interval different direction stable, sooth frequency dependencies

9 Test data (QSO J , Band 6 I Q U

10 Test data (QSO J , Band 3, P~6%

11 Capability at near future (tenta,ve! We will offer polarizaoon observaoons in near future under liitaoons as follows; bands 3, 6, and 7 (no band 9 cononuu only (no line (at a standard frequency in each observing band spaoally copact source saller than a fracoon of field of view single field w/12- only (no osaic, no ACA linearly- polarized iage only (no circular polarized flux of ~0.5% of the total flux can be iaged

12 The Atacaa Large Millieter/subillieter Array (ALMA, an international astronoy facility, is a partnership of Europe, North Aerica and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronoical Research in the Southern Heisphere (ESO, in North Aerica by the U.S. National Science Foundation (NSF in cooperation with the National Research Council of Canada (NRC and the National Science Council of Taiwan (NSC and in East Asia by the National Institutes of Natural Sciences (NINS of Japan in cooperation with the Acadeia Sinica (AS in Taiwan. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North Aerica by the National Radio Astronoy Observatory (NRAO, which is anaged by Associated Universities, Inc. (AUI and on behalf of East Asia by the National Astronoical Observatory of Japan (NAOJ. The Joint ALMA Observatory (JAO provides the unified leadership and anageent of the construction, coissioning and operation of ALMA.