White Dwarfs in the HET Dark Energy Experiment Bárbara G. Castanheira The University of Texas at Austin Universität Wien 17 th European White Dwarf Workshop – Tübingen, August 16-20, 2010

Hobby-Eberly Telescope Location: McDonald Observatory (30° 40' N) Low cost: 15-20% of the cost of a 9 m telescope Primary mirror: 11.1 x 9.8 m (9.2 m effective aperture) 91 hexagonal mirrors Fixed elevation angle of 55 o (tilted Arecibo design) Access 81% of the sky Queue schedule Instruments: HRS, LRS, MRS Model for SALT 17 th European White Dwarf Workshop – Tübingen, August 16-20, 2010

HETDEX: HET Dark Energy Experiment Goal: probe dark energy Observations: ~ 1400 hours in 3 years Technique: expansion of the universe at 0<z<4 Main targets: Lyman-α emitting galaxies 17 th European White Dwarf Workshop – Tübingen, August 16-20, 2010 (Hill et al. 2008)

Dark energy: 17 th European White Dwarf Workshop – Tübingen, August 16-20, 2010 Supernovae discovery of accelerated expansion Within GR: smooth energy with large negative pressure 75% of the universe Acceleration began at z~0.4 and t~10Gyr

(Frieman et al. 2008) 17 th European White Dwarf Workshop – Tübingen, August 16-20, 2010

Destiny of the universe depends critically upon the nature of dark energy!

17 th European White Dwarf Workshop – Tübingen, August 16-20, 2010 HETDEX field:

VIRUS-P Review:  Visual Integral-field Replicable Unit Spectrograph - Prototype  1.9’x1.9’ FOV at 2.7 m HJST  1/3 fill factor  Largest FOV of any existing IFU  4.2’’ diameter fibers on sky  Å wavelength range  5000Å 17 th European White Dwarf Workshop – Tübingen, August 16-20, 2010

Flux calibrating the pilot survey: 17 th European White Dwarf Workshop – Tübingen, August 16-20, 2010 Feige 34

17 th European White Dwarf Workshop – Tübingen, August 16-20, 2010 Dither 1:

17 th European White Dwarf Workshop – Tübingen, August 16-20, 2010 Dither 2:

17 th European White Dwarf Workshop – Tübingen, August 16-20, 2010 Dither 3:

17 th European White Dwarf Workshop – Tübingen, August 16-20, 2010 Dither 4:

17 th European White Dwarf Workshop – Tübingen, August 16-20, 2010 Dither 5:

17 th European White Dwarf Workshop – Tübingen, August 16-20, 2010 Dither 6:

17 th European White Dwarf Workshop – Tübingen, August 16-20, 2010 Feige 34: VIRUS-P 2.7m HJST 6x120sV=11.2

17 th European White Dwarf Workshop – Tübingen, August 16-20, 2010 HETDEX details: 150 VIRUS Å ~3400 spectra FOV 22arcmin Resolution ~5Å ~140 nights, 3 years PARALLEL SURVEY

(Drory 2010) 17 th European White Dwarf Workshop – Tübingen, August 16-20, 2010

White Dwarfs in HETDEX  ~20000 White Dwarfs  Magnitude limited sample  For V=22, S/N=3  Main and Parallel surveys A powerful survey!

17 th European White Dwarf Workshop – Tübingen, August 16-20, 2010 HETDEX current status:  Schedule: late 2011  VIRUS-P at HET  Replication of spectrographs  Software (CURE or VACCINE & DIAGNOSE)  Additional science

17 th European White Dwarf Workshop – Tübingen, August 16-20, 2010 White dwarf science goals:  WD Luminosity Function  New candidates of pulsators (2.1m)  New “flavors” of WDs?

17 th European White Dwarf Workshop – Tübingen, August 16-20, 2010 Danke! Obrigada!