Constraining the Global 21-cm Signal with EDGES and Applications for - - PowerPoint PPT Presentation

Constraining the Global 21-cm Signal with EDGES and Applications for DARE

Raul Monsalve

for the EDGES and DARE collaborations

Science at Low Frequencies III, Caltech, USA December 8, 2016

EDGES

Experiment to Detect the Global EoR Signature

• Prof. Judd Bowman (PI)
• Dr. Alan Rogers
• Mr. Thomas Mozdzen
• Dr. Raul Monsalve

Two EDGES Instruments

EDGES Low Band

EDGES High Band

EDGES MRO

Location

EDGES High-Band 2015-2016

Antenna size: 1m long / 0.5m high Operated between: August 2015 & September 2016 Ground plane: 10m x 10m

EDGES Low-Band 2015-2016

Ground plane: 10m x 10m Antenna size: 2m long / 1m high With OLD ground plane Operated between: October 2015 & September 2016

NEW (Sept 2016) Low-Band Ground Plane

20m 20m 5m NEW Ground Plane: Central Square: 20m x 20m 16 Triangles: 5m-long Welding Wiregrid Panels

OLD Ground Plane NEW Ground Plane

Example 10-day averages:

OLD NEW 180 mK 68 mK

Factor ~3 improvement due to NEW Ground Plane

Focusing on EDGES High-Band …..

Absorption Trough Model

Cyan: Mesinger et al. (2013) Red: Fialkov et al. (2016b) Blue: Mirocha et al. (2016)

• =

·

: Gaussian center ∆: Gaussian FWHM

Gaussian Phenomenological Model

Absorption Trough in some current models falls within EDGES High-Band range

Sample of Gaussian Models

Foreground Models

Physical model = #.% &' +&(*+,#) + &(*+,#)+&.#.' + &#'.%

• /01(#) = “Baseline” Model + 21-cm Model

Foregrounds + Ionosphere + Calibration Residuals

EDGES Polynomial = #.% 7 &8#8

9 8:'

Measurements: Spectrum and Residuals

Monsalve et al., in preparation About 100 hours of Low-Foreground observations

Measurements: Preliminary Rejections

; < ≥ −150mK + 2 · D Monsalve et al., in preparation

Monsalve et al., in preparation

EFG = −FHI JK EFG = −HI JK

Measurements: Preliminary Rejections

Rejection Examples

Preliminarily Rejected Preliminarily NOT Rejected

Physical Models: Fialkov, Cohen, et al.

Monsalve et al., in preparation Fialkov et al. (2016) Cohen et al. (2016)

Physical Models: Mirocha et al.

Monsalve et al., in preparation Discussed in Mirocha et al. (2013) Cold EoR scenarios:

• Strong Lyman alpha coupling.
• No X-ray heating.
• Optical depth consistent with

Planck.

• Ionization completed by z = 6.

Main Characteristics

• DARE probes z=11-35, or ν=40-120 MHz.
• Two Year Mission Lifetime.
• 800 hrs integration above lunar farside shielded from Sun.
• 50 x 125 km circular, equatorial orbit.
• Instrument: biconical dipole antenna, pilot-tone injection receiver, digital spectrometer,

polarimeter.

• Calibration based on EDGES as a ground-based precursor.
• DARE will be submitted as a mission proposal to NASA’s MIDEX program by December 15, 2016.

1.6 m

On-orbit Beam Measurements

Green Bank Observatory 140-ft antenna

• Circularly polarized, PSK modulated carriers are sent

from the ground to DARE.

• DARE receives signals as the spacecraft orbits above near

side of the Moon to sweep beam.

• Carrier levels are measured by DARE every 20 seconds to

produce sampled beam cut.

• A weak signal is also measured on its return trip to the

Earth (Moon reflection) to estimate real-time path loss through the ionosphere.

DARE Observatory

• MCMC inference pipeline (same as LIGO, CMB).
• SVD modeling of measurement uncertainties, and 21-cm models.

Liu et al. (2013), Vedantham et al. (2014), Switzer & Liu (2014).

Summary

• Quality of data from EDGES Low-Band has increased significantly due to

improved, 25m x 25m ground plane. Measurements ongoing.

• Data from EDGES High-Band enable to rule out wide range of Gaussian-like

absorption troughs. For amplitude of -150 mK, preliminarily rejected widths LMN ∆O < Q.

• A wide variety of physical models can also be rejected, in particular of Cold EoR

scenarios.

• The high-heritage, precision cosmology DARE space mission is being proposed to

NASA’s MIDEX program in December 2016.