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Detecting faint submm galaxies using RADIO lensing the case of the cluster MS0451

Detecting faint submm galaxies using RADIO lensing the case of the cluster MS0451. Dr . Léon Koopmans ( Kapteyn Institute) Prof. Mike Garrett (ASTRON) Dr. Olaf Wucknitz ( AIfA Bonn) . Alicia Berciano Alba ( Kapteyn Institute). OZ Lens 2008, Sydney (Australia) .

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Detecting faint submm galaxies using RADIO lensing the case of the cluster MS0451

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  1. Detecting faintsubmm galaxies using RADIOlensingthe case of the cluster MS0451 Dr.Léon Koopmans (Kapteyn Institute) Prof. Mike Garrett (ASTRON) Dr. Olaf Wucknitz( AIfA Bonn) Alicia Berciano Alba (Kapteyn Institute) OZ Lens 2008, Sydney (Australia)

  2. The relevance of dust obscured galaxies Optical/UV light Starburst galaxy SED IR/submm dust re-radiated light dust re-radiated Critically important to understand galaxy formation and evolution ~ 50% of the total radiation in the universe dust obscured galaxies

  3. Submm-galaxies in a nutshell • SMGs = dusty, FIR luminous starburst galaxies at high redshift • Discovered with SCUBA (JCMT) at 850 mm (Smail, Ivison & Blain 1997) BrightSMGs (whatwe can see) 2 mJySCUBA’s confussionlimit at 850 mm FaintSMGs (the unknownterritories) Properties of brightSMGs: • Median redshift ~ 2.3 • LFIR > 1012Lsun ULIRGs • SFR ~103Msun/yr • Gas-richmergers • Dusttemperature ~ 35K • Mgas ~ 1010 – 1011Msun Bulk of the submm background energy at 850 mm (Knudsen , van derWerf & Kneib 2007)

  4. My lab rat : MS0451.6 - 0305

  5. Source plane ERO B LBG EROC ~ 10 Kpc Once upon a time … Borys et al. 2004 Image plane MERGER!!! Data: Optical : HST F702W, F775W, F850LP NIR (circles) : CFHT JHK’- band Submm (contours): SCUBA 850 mm Redshifts: LBG ARC1 :z = 2.911 (VLT spectroscopy) EROs* B,C : z = 2.85 (lens model) *Extremely Red Objects

  6. FIR Submm Radio interferometryto the rescue High-z starburst: Observed in submm = emitted in FIR dust re-processed UV radiation frommassivestars FIR (submm) Massive star formation synchrotronemmisionfrom electronsgeneratedby SN Radio High resolution “version” of the submm map Radio interferometry

  7. Radio observations : VLA 1.4GHz (20 cm) • B-array(Berciano Alba et al. 2007) • 2 x 4 hours (9th and 10th June 2002) • Project ID AN109, PI: Nakanishi • Resolution: 6.34” x 4.87” pa= 7.73 • A-array • 2 x 6 hours (5th and 10th Feb 2006) • Resolution: 2.07” x 1.58” pa= -1.19 • Data reduction: AIPS + ParselTongue

  8. A+B array naturaly weighted 1.4GHz map CR1 CR2 Resolution = 2.78 x 2.18 arcsecs pa=-0.21 rms noise = 10.16 mJy/beam Grey scale: 3 x noise Contours:4, 5, 6, 8 and 10 x noise

  9. Radio detections located withing the submm emission SNR ~ 6 (flux ~ 34 mJy) SNR ~ 4.5 CR1 (flux ~ 23 mJy) SNR ~ 4.6 SNR ~ 6 CR2 (flux ~ 28 mJy) (flux ~ 42 mJy) SNR ~ 11 (flux ~ 170 mJy) SNR ~ 5 (flux ~ 52 mJy) 4 detections: RJ, E1, E2, E3 2 tentative detections: C1, C2

  10. Multi-wavelenght counterparts of the radio detections Positional Errors • Radio: FWHM / (2*SNR)  between 0.1” and 0.3” • NIR: 0.2” (fitting error for the standard stars used for the astrometry) Alignment Radio and NIR map aligned respect to the HST map • Radio: 13 sources, rms distance = 0.29” • NIR: 93 sources, rms distance = 0.06” Data • Optical: HST ACS F814W ( Moran et al 2007 ) • NIR: Subaru CISCO K’-band ( Takata et al 2003 )

  11. White contours: 20cm radio emission Blue squares: NIR sources Yellow squares: optical arcs produced by a LBG

  12. Source plane ERO B LBG EROC ~ 10 Kpc zphoto = 0.45 MERGER!!!

  13. Not associated with the lensedsubmm emission!!! zphoto = 0.4 AGN + radio jet • Extended source: ~ 3 beams (~ 6”) • Peak not consistent with any optical counterpart • mayor axis aligned with a posible cluster member

  14. Radio vs submm emission Radio contours = 3,4,5,6 and 7 x 30 mJy/beam

  15. CONCLUSIONS ON MS0451 (so far…) • The brightest radio detection (RJ) is not related with the lensedsubmm emission (probably an AGN jet) • The other radio detections (E1,E2,E3,CR1,CR2) are counterparts of the submm emission • 2 radio detections (E1,E2) confirm that ERO B is associated with the submm emission • 2 tentative radio detections (CR1,CR2) support the merger hypothesis

  16. THE FUTURE • The coming years will see a revolution in radio / mm interferometric observations: EVLA, eMERLIN, ALMA, SKA, LOFAR… • Window to study high redshift dust obscured universe unnaccesible in optical • Time to think about robustmultiwavelenght source reconstruction

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