Presentation Information
[O12-P80]Observation of 21cm using a homemade horn antenna
*Tatsuki Wada1, *Nodoka Kameda1, *Anna Umezawa1, *Toa Shimozyo1 (1. Tokyo Metropolitan High School of Science and Technology)
Keywords:
dark matter,Galactic rotation curve
Summary: Detecting Dark Matter via 21 cm Line Observations with a DIY Horn Antenna
1. Introduction and Objectives
The study addresses the mystery of dark matter by analyzing the galactic rotation curve of the Milky Way. Specifically, it focuses on the 21 cm line emitted by neutral hydrogen through hyperfine structure transitions. Unlike previous studies requiring large parabolic antennas, this research aims to prove that a high-school-level observation system—utilizing a low-cost, homemade horn antenna—can successfully detect galactic structures and provide empirical evidence for the existence of dark matter.
2. Instrumentation and Methodology
The researcher constructed a horn antenna using readily available materials like aluminum tape. The signal processing chain included:
• Hardware: A Low-Noise Amplifier (LNA) and a GW Instek GSP-9330 spectrum analyzer.
• Settings: Resolution and Video Bandwidth were both set to 10 kHz to maximize frequency resolution for Doppler shift detection.
• Target: Galactic longitudes l = 40^\circ to 260^\circ at the 1420.406 MHz frequency.
• Software: A custom Python program was used to integrate data and cancel random noise.
3. Analysis and Results
Radial velocity was derived via the Doppler effect equation. For the inner galaxy (l < 90^\circ), the tangent point method was used to calculate rotation velocity.
Key Findings:
• Flat Rotation Curve: Observations indicated that rotation speeds do not decrease at the outer edges of the galaxy. This discrepancy from visible mass predictions strongly suggests the presence of widely distributed dark matter.
• RFI Interference: An anomalous result of 600 km/s was detected at certain longitudes. This was identified as Radio Frequency Interference (RFI) from terrestrial electronics rather than a true hydrogen signal.
• System Correction: Current data does not yet include Local Standard of Rest (LSR) corrections for Earth's motion.
4. Conclusion and Future Outlook
The study successfully demonstrates that significant astronomical data can be obtained using accessible, DIY equipment. By optimizing bandwidth settings and data integration, the author confirmed the primary dynamical characteristics of the Milky Way.
Future Work includes:
1. Filling data gaps in specific galactic longitudes.
2. Improving noise filtering to eliminate RFI outliers.
3. Implementing LSR correction algorithms to fit the data to precise dark matter mass distribution models.
1. Introduction and Objectives
The study addresses the mystery of dark matter by analyzing the galactic rotation curve of the Milky Way. Specifically, it focuses on the 21 cm line emitted by neutral hydrogen through hyperfine structure transitions. Unlike previous studies requiring large parabolic antennas, this research aims to prove that a high-school-level observation system—utilizing a low-cost, homemade horn antenna—can successfully detect galactic structures and provide empirical evidence for the existence of dark matter.
2. Instrumentation and Methodology
The researcher constructed a horn antenna using readily available materials like aluminum tape. The signal processing chain included:
• Hardware: A Low-Noise Amplifier (LNA) and a GW Instek GSP-9330 spectrum analyzer.
• Settings: Resolution and Video Bandwidth were both set to 10 kHz to maximize frequency resolution for Doppler shift detection.
• Target: Galactic longitudes l = 40^\circ to 260^\circ at the 1420.406 MHz frequency.
• Software: A custom Python program was used to integrate data and cancel random noise.
3. Analysis and Results
Radial velocity was derived via the Doppler effect equation. For the inner galaxy (l < 90^\circ), the tangent point method was used to calculate rotation velocity.
Key Findings:
• Flat Rotation Curve: Observations indicated that rotation speeds do not decrease at the outer edges of the galaxy. This discrepancy from visible mass predictions strongly suggests the presence of widely distributed dark matter.
• RFI Interference: An anomalous result of 600 km/s was detected at certain longitudes. This was identified as Radio Frequency Interference (RFI) from terrestrial electronics rather than a true hydrogen signal.
• System Correction: Current data does not yet include Local Standard of Rest (LSR) corrections for Earth's motion.
4. Conclusion and Future Outlook
The study successfully demonstrates that significant astronomical data can be obtained using accessible, DIY equipment. By optimizing bandwidth settings and data integration, the author confirmed the primary dynamical characteristics of the Milky Way.
Future Work includes:
1. Filling data gaps in specific galactic longitudes.
2. Improving noise filtering to eliminate RFI outliers.
3. Implementing LSR correction algorithms to fit the data to precise dark matter mass distribution models.