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GBT 21 cm intensity mapping collaboration

GBT 21 cm intensity mapping collaboration. Academia Sinica (Tzu-Ching Chang, Victor Yu-wei Liao ) Beijing (Xuelei Chen, Yi-Chao Li ) Carnegie Mellon University ( Aravind Natarajan , Jeff Peterson, Tabitha Voytek )

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GBT 21 cm intensity mapping collaboration

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  1. GBT 21 cm intensity mapping collaboration • Academia Sinica (Tzu-Ching Chang, Victor Yu-wei Liao) • Beijing (Xuelei Chen, Yi-Chao Li) • Carnegie Mellon University (Aravind Natarajan, Jeff Peterson, Tabitha Voytek) • CITA/UToronto (Nidhi Banavar, Liviu Calin, Adam Lewis, Kiyo Masui, Ue-Li Pen, Richard Shaw, Eric Switzer) • McGill (Kevin Bandura)

  2. ARAA review article May 2010 (Morales and Wyithe) comparing to z ~ 10: Two months later:

  3. IM: now and then

  4. RFI Liu and Tegmark 2011

  5. The real data

  6. Signal-only simulations 20 Mpc ΩHI = 10-3

  7. Relaxed quadratic estimation Most general: Inverse covariance, down-weight foreground in both angle and frequency. Imperfect spectral baseline – need non-parametric removal: SVD on cross maps Liu & Tegmark MNRAS, Volume 419, Issue 4, pp. 3491-3504. Projecting (idempotent) LOS modes is “good enough” vs. optimal downweighting. These suggest that our method is slightly sub-optimal (in theory), but ideal in practice because we use the covariance of the real data!

  8. SVD eigenvalues Eigenvalue Mode number (sorted) Modes falling off rapidly: few DOF to describe most of the foregrounds.

  9. Real data, cleaned (25 modes removed here.)

  10. Cross-pairs: GBT power ( Weight A ) * Map A ( ) Weight B × * Map B

  11. Cross-pairs: WiggleZ crosspower ( ) Weight A * Map A ( ) Selection function × * Galaxy catalog

  12. Preliminary

  13. Fisher-matrix predictions

  14. Conclusions • End-to-end demonstration: calibration, ionosphere, point sources, galaxy, spectral response, etc. No show stoppers. Lessons learned for EoR. • Foreground subtraction under control: ready for z~1 21cm intensity mapping. • Consistent autonomous 21cm maps and power spectra. • Proposal for GBT 0.5<z<1 BAO survey using new ASIAA 9 pixel receiver array starting 2013. • Retires major risk for CHIME!

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