constraining the global redshifted 21-cm signal with edges in the
TRANSCRIPT
Constraining the Global 21-cm Signal with EDGES
and Applications for DARE
Raul Monsalvefor the EDGES and DARE collaborations
Science at Low Frequencies III, Caltech, USA December 8, 2016
EDGESExperiment 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
Physicalmodel = #�.% &'+&�(*+,#) + &�(*+,#)�+&.#�.' + &�#'.%
�/01(#) = “Baseline” Model + 21-cm Model
Foregrounds + Ionosphere + Calibration Residuals
EDGESPolynomial = #�.%7&8#89
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 = −FHIJK
EFG = −HIJK
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.