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HADS in the Large Magellanic Cloud : Initial findings from the SuperMACHO Project

HADS in the Large Magellanic Cloud : Initial findings from the SuperMACHO Project. Arti Garg Lawrence Livermore National Laboratory, Institute of Geophysics and Planetary Physics. Stellar Pulsation, Santa Fe, NM June 4, 2009 LLNL-PRES-413511.

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HADS in the Large Magellanic Cloud : Initial findings from the SuperMACHO Project

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  1. HADS in the Large Magellanic Cloud:Initial findings from the SuperMACHO Project Arti Garg Lawrence Livermore National Laboratory, Institute of Geophysics and Planetary Physics Stellar Pulsation, Santa Fe, NM June 4, 2009 LLNL-PRES-413511 This work work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  2. Microlensing to Detect MACHOs • In 1986, B. Paczynski suggested using gravitational microlensing toward the Magellanic Clouds to detect MACHOs Milky Way Halo Us Large Magellanic Cloud Light Path Anglo-Australian Observatory/ Royal Observatory Edinburgh MW illustration: Mark Garlick (Space-art) Earth Image: Apollo 17 MACHOs

  3. SuperMACHO ProjectLLNL/IGPP: A. Garg, K.H. Cook, S.Nikolaev,Harvard: A. Rest, C.W. Stubbs (P.I.), P. Challis, W.M. Wood-Vasey, G. Narayan, NOAO:R.C. Smith, K. Olsen, A. Zenteno, JHU:M.E. Huber,UW:A. Becker, A. Miceli, FNAL: G. Miknaitis, McMaster: D.L. Welch, Catolica: A. Clocchiati, D. Minniti,Padova: L. Morelli, OSU: J.L. Prieto, UT-Austin: N.B. Suntzeff • CTIO 4m • Mosaic Imager: big FOV • Monitor 68 LMC fields • 23 deg2 and ~50 million sources • 150 half-nights • 5 years (2001-2006) • Blocks of ~3 months/year • Near real-time detection • Single filter: custom VR • Difference imaging

  4. SuperMACHO fields Primary field set Secondary field set Image: Gregory Bothun

  5. Difference Imaging Reference Image flux(ttempl) Difference Image flux(timage) – flux(ttempl) Detection Image flux(timage)

  6. RR Lyrae from MACHO (black) and SuperMACHO (red)

  7. Periodic Variables High Amplitude δ-Scuti 1580 candidates • Selection based on: • P-L diagram • Color (B-I) • Amplitude (> 0.2mag) Garg 2009

  8. Light Curves VR VR Phase Phase VR VR Phase Phase Garg et al., in prep.

  9. MACHO low amplitude variability limit Color-Magnitude Diagram Garg et al., in prep.

  10. VR = −3.65±0.07 log10P + 16.72±0.146 (Poretti et al. 2008) Period-Luminosity Diagram VR VR = −3.49±0.313 log10P + 16.94±0.357 Median Mode log10P Garg et al., in prep.

  11. VR-intercept Overtone Pulsators? VRint,-3.65 = 3.65 log10P + VR VRint,-3.49 = 3.49 log10P + VR Garg et al., in prep.

  12. Light Curve Shape r21 r31 VRint,-3.49 VRint,-3.49 0.06804 days, 1.63296 hours r41 0.07035 days, 1.68840 hours 0.07283 days, 1.74792 hours 0.07742 days, 1.85808 hours VRint,-3.49 Garg et al., in prep.

  13. Amplitude of Pulsation Fornax 0.06735 days, 1.1640 hours 0.0909 days, 2.1816 hours Amplitude (mag) • Cole et al. (2005) find evidence for lower metallicity population in LMC • Not enough to explain the position of peak assuming metallicity dependence of McNamara et al (2004) VRint,-3.49 Garg et al., in prep.

  14. Distance to the LMC Mv = – 3.65(±0.07) log10P – 1.83(±0.08) – 0.19 [Fe/H] (Poretti et al. 2008; McNamara et al. 2004) Distance = 18.58±0.184 Mv = – 3.49(±0.313) log10P – 1.83(±0.08) – 0.19 [Fe/H] (This work; McNamara et al. 2004) Distance = 18.80±0.374 [Fe/H] = – 0.37(±0.15) (Cole et al. 2005) MV = MVR+0.10(±0.074) (From RR Lyrae in MACHO and SuperMACHO)

  15. The SuperMACHO survey was undertaken as part of the NOAO Survey Program.

  16. SM-2004-LMC-821 VR≈21 Spectral classification: Broad Absorption Line AGN

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