Reference Array and Design Consideration for the Next-Generation Event Horizon Telescope
Abstract
:1. Introduction
2. ngEHT Concept
3. Next Generation Science Goals
3.1. Existence and Properties of Black Hole Horizons
3.2. Measurements of the Spin of a SMBH
3.3. Evolution of Supermassive Black Holes
3.4. Mechanisms of Black Hole Accretion
3.5. Heating and Acceleration of Relativistic Electrons
3.6. Energy Extraction from Black Holes
3.7. Jet Formation
3.8. Constraining Properties of the Black Hole Photon Ring
4. Optimizing the ngEHT Reference Array
4.1. Candidate Sites
4.2. Synthetic Data Generation
4.3. Array Performance Metrics
4.4. Site Selection
- in observations of both M87* and Sgr A*;
- during observations that take place throughout the year;
- when observing alongside any subset of the EHT.
4.4.1. Phase 1
- An “eastern cluster” containing two sites in South America and either CNI or, less frequently, one of the other mainland European sites (BGA, SKS, SPX).
- A “western cluster” containing two sites in South America and a site in North America, most typically either SPM, PIKE, or FAIR.
- A “northern cluster” containing two sites in South America and GLTS, or less commonly with BGK.
- A “southern cluster” containing two sites in South America and one of the Antarctic Dome sites.
- An “equatorial cluster” containing one site in South America, one site in North America, and CNI.
- A “polar cluster” containing one site in South America, GLTS, and one of the Antarctic Dome sites.
4.4.2. Phase 2
4.4.3. Alternate Staging of New Sites
4.4.4. Baseline Coverage
5. Operating Modes
5.1. Campaign
5.2. Long-Term Monitoring
5.3. Target of Opportunity
5.4. Coordinated Multi-Facility
5.5. Beyond ngEHT
6. Data Processing
6.1. Data Transport
6.2. Correlation
6.3. Calibration and Reduction
7. Instrumentation Design
7.1. Receiver
7.2. Backend
7.3. Recorder
7.4. Array Monitoring and Control
- 60 nights of observing per year
- Up to 21 stations observing simultaneously
- Varied observation cadences and durations throughout the year
- Readiness for VLBI observing in 24 h or less to capture ToOs
- Multi-messenger campaigns
- Configurable subarrays
- As much remote operation as possible
7.5. Antennas
8. Summary and Conclusions
Author Contributions
Funding
Data Availability Statement
Acknowledgments
Conflicts of Interest
Appendix A. Additional Site Selection Details
Site Code | Location | Latitude | Longitude | Elevation (m) |
---|---|---|---|---|
ALMA | Atacama, Chile | −23.032 | −67.755 | 5040 |
AMT | Gamsberg, Namibia | −23.339 | 16.229 | 2340 |
APEX | Atacama, Chile | −23.005 | −67.759 | 5060 |
GLT | Pituffik Space Base, Greenland | 76.535 | −68.686 | 70 |
HAY | Westford, Massachusetts, USA | 42.624 | −71.489 | 110 |
IRAM | Sierra Nevada, Spain | 37.066 | −3.393 | 2860 |
JCMT | Mauna Kea, Hawaii | 19.823 | −155.477 | 4070 |
KP | Arizona, USA | 31.953 | −111.615 | 1930 |
KVNPC | Pyeongchang, South Korea | 37.534 | 128.450 | 500 |
KVNYS | Yonsei, South Korea | 37.565 | 126.941 | 90 |
LLA | Salta, Argentina | −24.192 | −66.475 | 4780 |
LMT | Sierra Negra, Mexico | 18.986 | −97.315 | 4620 |
NOEMA | Plateau de Bure, France | 44.634 | 5.907 | 2550 |
OVRO | California, USA | 37.231 | −118.282 | 1210 |
SMA | Mauna Kea, Hawaii | 19.824 | −155.478 | 4070 |
SMT | Arizona, USA | 32.702 | −109.891 | 3170 |
SPT | South Pole, Antarctica | −90 | 0 | 2820 |
ALI | Hotan County, China | 35.963 | 79.338 | 6080 |
BAN | Alberta, Canada | 51.350 | −116.206 | 3470 |
BAR | California, USA | 37.634 | −118.256 | 4340 |
BGA | Progled, Bulgaria | 41.695 | 24.738 | 1730 |
BGK | Westfjords, Iceland | 66.032 | −23.052 | 830 |
BLDR | Colorado, USA | 39.588 | −105.643 | 4340 |
BMAC | Eastern Cape, South Africa | −31.096 | 27.889 | 2420 |
BOL | La Paz, Bolivia | −16.351 | −68.131 | 5230 |
BRZ | Espírito Santo, Brazil | −20.439 | −41.799 | 2850 |
CAS | Tierra del Fuego, Argentina | −54.790 | −68.415 | 2850 |
CAT | Río Negro, Argentina | −41.170 | −71.486 | 2100 |
CNI | La Palma, Canary Islands | 28.299 | −16.509 | 2360 |
DomeA | Upper ice sheet, Antarctica | −80.367 | 77.351 | 4090 |
DomeC | Upper ice sheet, Antarctica | −75.101 | 123.342 | 3230 |
DomeF | Upper ice sheet, Antarctica | −77.317 | 39.702 | 3700 |
ERB | Khalifan, Iraq | 36.584 | 44.466 | 2110 |
FAIR | Alaska, USA | 64.988 | −147.599 | 620 |
FLWO | Arizona, USA | 31.675 | −110.951 | 1270 |
FUJI | Fujinomiya & Yamanashi, Japan | 35.367 | 138.730 | 3750 |
GARS | Trinity Peninsula, Antarctica | −63.320 | −57.895 | 20 |
GLTS | Ice sheet summit, Greenland | 72.580 | −38.449 | 3230 |
HAN | Ladakh, India | 32.780 | 78.963 | 4500 |
JELM | Wyoming, USA | 41.097 | −105.977 | 2940 |
KEN | Meru, Kenya | −0.141 | 37.315 | 4260 |
KILI | Kilimanjaro, Tanzania | −3.088 | 37.406 | 4430 |
LCO | Coquimbo, Chile | −29.032 | −70.685 | 2320 |
LOS | New Mexico, USA | 35.880 | −106.675 | 2000 |
NOB | Nagano, Japan | 35.944 | 138.472 | 1370 |
NZ | Canterbury, New Zealand | −43.987 | 170.465 | 1010 |
ORG | Oregon, USA | 42.635 | −118.576 | 2970 |
PAR | Antofagasta, Chile | −24.628 | −70.404 | 2640 |
PIKE | Colorado, USA | 38.841 | −105.041 | 4280 |
SAN | California, USA | 34.099 | −116.825 | 3500 |
SGO | Santiago, Chile | −33.3346 | −70.270 | 3350 |
SKS | Crete, Greece | 35.212 | 24.898 | 1740 |
SPM | Baja California, Mexico | 31.045 | −115.464 | 2800 |
SPX | Fieschertal, Switzerland | 46.548 | 7.985 | 3510 |
SUF | Zaamin, Uzbekistan | 39.623 | 68.468 | 2440 |
TRL | Jutulsessen, Antarctica | −72.010 | 2.540 | 1280 |
VLA | New Mexico, USA | 34.079 | −107.618 | 2120 |
YAN | Huanca Sancos, Peru | −13.938 | −74.392 | 4230 |
YBG | Lhasa Tibet, China | 30.006 | 91.027 | 5360 |
Parameter Set | Pre-Existing Stations from EHT Array | Other Pre-Existing Stations Assumed |
---|---|---|
Phase 1 set 1 | none | HAY, OVRO |
Phase 1 set 2 | LMT | HAY, OVRO |
Phase 1 set 3 | APEX, GLT, JCMT, LMT, SMT | HAY, OVRO |
Phase 1 set 4 | ALMA, APEX, GLT, IRAM, JCMT, KP, LMT, NOEMA, SMA, SMT, SPT | HAY, OVRO |
Phase 2 set 1 | none | CNI, HAY, LCO, OVRO, SPM |
Phase 2 set 2 | LMT | CNI, HAY, LCO, OVRO, SPM |
Phase 2 set 3 | APEX, GLT, JCMT, LMT, SMT | CNI, HAY, LCO, OVRO, SPM |
Phase 2 set 4 | ALMA, APEX, GLT, IRAM, JCMT, KP, LMT, NOEMA, SMA, SMT, SPT | CNI, HAY, LCO, OVRO, SPM |
1 | Available online: https://www.mdpi.com/journal/galaxies/special_issues/ngEHT_blackholes (accessed on 16 August 2023). |
2 | Available online: https://github.com/Smithsonian/ngehtsim (accessed on 16 August 2023). |
3 | Available online: https://www.evlbi.org/ (accessed on 16 August 2023). |
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Key Science Goal | Source | ngEHT Phase | References |
---|---|---|---|
Establish the existence | M87* | Phase 1 | Chael et al. [47]; |
of black hole horizons | Sgr A* | Phase 2 | Dokuchaev and Nazarova [48] |
Measure a SMBH’s spin | M87* | Phase 2 | Palumbo et al. [49] |
Sgr A* | Phase 2 | Ricarte et al. [50] | |
Understanding Black Hole-Galaxy | AGN Survey | Phase 1 | Pesce et al. [51,52] |
Formation, Growth and Coevolution | Ramakrishnan et al. [53] | ||
Reveal how black holes | M87* | Phase 1 | Balbus and Hawley [54]; |
accrete material | Sgr A* | Phase 2 | Yuan and Narayan [55] |
Observe localized electron | M87* | Phase 1 | Rowan et al. [56]; |
heating and acceleration | Sgr A* | Phase 2 | Ball et al. [57] |
Determine if BH jets are | M87* | Phase 2 | Blandford and Znajek [58]; |
powered by spin energy | Sgr A* | Phase 2 | Tchekhovskoy et al. [59] |
Determine jet formation | M87* | Phase 1 | Blandford et al. [60] |
& launching mechanisms | Sgr A* | Phase 2 | |
Constraining Properties | M87* | Phase 2 | Johnson et al. [61]; |
of the BH Photon Ring | Sgr A* | Phase 2 | Tiede et al. [62] |
Site | Status | EHT | ngEHT | ngEHT | ngEHT |
---|---|---|---|---|---|
Phase 1 | Phase 2 | Phase 2 (alt.) | |||
ALMA | existing | 86 230 345 | 86 230 345 | 86 230 345 | 86 230 345 |
AMT | planned | - | - | - | 86 + 230 + 345 |
APEX | existing | 230 345 | 86 230 345 | 86 230 345 | 86 230 345 |
BOL | planned | - | - | 86 + 230 + 345 | - |
CNI | planned | - | 86 + 230 + 345 | 86 + 230 + 345 | 86 + 230 + 345 |
GLT | existing | 86 230 345 | 86 + 230 + 345 | 86 + 230 + 345 | 86 + 230 + 345 |
HAY | existing | - | 86 + 230 | 86 + 230 | 86 + 230 |
IRAM | existing | 86 + 230 345 | 86 + 230 345 | 86 + 230 345 | 86 + 230 345 |
JCMT | existing | 86 230 345 | 86 + 230 + 345 | 86 + 230 + 345 | 86 + 230 + 345 |
JELM | planned | - | - | 86 + 230 + 345 | 86 + 230 + 345 |
KILI | planned | - | - | 86 + 230 + 345 | - |
KP | existing | 86 230 | 86 + 230 | 86 + 230 | 86 + 230 |
KVNPC | planned | - | - | - | 86 + 230 + 345 |
KVNYS | existing | - | - | - | 86 + 230 + 345 |
LCO | planned | - | 86 + 230 + 345 | 86 + 230 + 345 | 86 + 230 + 345 |
LLA | planned | - | - | - | 86 + 230 + 345 |
LMT | existing | 86 230 | 86 + 230 + 345 | 86 + 230 + 345 | 86 + 230 + 345 |
NOEMA | existing | 86 230 345 | 86 + 230 345 | 86 + 230 345 | 86 + 230 345 |
OVRO | existing | - | 86 + 230 | 86 + 230 | 86 + 230 |
SGO | planned | - | - | 86 + 230 + 345 | - |
SMA | existing | 230 345 | 230 345 | 230 345 | 230 345 |
SMT | existing | 230 345 | 86 + 230 + 345 | 86 + 230 + 345 | 86 + 230 + 345 |
SPM | planned | - | 86 + 230 + 345 | 86 + 230 + 345 | 86 + 230 + 345 |
SPT | existing | 230 | 86 + 230 + 345 | 86 + 230 + 345 | 86 + 230 + 345 |
SPX | planned | - | - | 86 + 230 + 345 | - |
OpsMode | Stations in Array | Cadence & Duration | Science Case |
---|---|---|---|
Campaign | 14 to 21 | once per year | Sgr A*, M87 |
7-day session | blazars, jets | ||
Long term | 5 to 20 | once per 3 to 5 days, | M87* & blazar kinematics, |
monitoring | for 3 to 7 months | Sgr A* flares | |
Target of | 3 to 6 | once per week | flares, |
Opportunity | during obs. season | gravitational waves | |
CMF | 14 to 21 | during Campaign | AGNs, black hole binaries |
Beyond | 1 to 10 | dependent on | stellar birth, |
ngEHT | science case | fast radio bursts |
Item | Description |
---|---|
3 mm RF Band | 82–116 GHz |
1 mm RF Band | 210–280 GHz |
850 m RF Band | 275–375 GHz |
Polarizations | Dual pol in each band |
Sidebands | 2SB Receivers in each band |
IF Frequency | 4–12 GHz (1 mm, 0.85 m) |
4–8 GHz (3 mm) | |
Receiver Noise | <50 K in 3 mm band |
Temperature | 60–70 K in 1 mm band |
70–80 K in 850 m band |
Mark6 | ngRecorder | |
---|---|---|
rack space | 11U | 2U |
disks | 32 HDD | 24 SSD |
capacity | 512 TB | 369 TB |
interface | 4 × 10/25 GbE | 2 × 100 GbE |
rate | 16/32 Gbps | 128 Gbps |
hours at rate | 71.1/35.6 | 6.4 |
disk modules | yes | no |
Design Specifications | |
---|---|
Primary reflector diameter | 9 m |
Mount architecture | Alt-Az |
Optics | Cassegrain |
Sun avoidance zone | None |
Operating Specifications | |
Surface accuracy | 30 m rms |
Frequency range | 86–345 GHz |
Aperture efficiency | 0.8 |
Pointing accuracy | 2 rms (all sky, blind) |
Tracking accuracy | |
Aperture blockage | <5% |
Gain variation with elevation | <5% |
Range of motion in azimuth | −180–360, |
Range of motion in elevation | 3–90, |
Slew speed | 1/s |
Environmental Specifications | |
Temperature | −15 to +35 °C operational |
−20 to +45 °C high | |
−30 to +55 °C survival | |
Wind speed | 10 m/s operational |
15 m/s high | |
50 m/s survival |
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Doeleman, S.S.; Barrett, J.; Blackburn, L.; Bouman, K.L.; Broderick, A.E.; Chaves, R.; Fish, V.L.; Fitzpatrick, G.; Freeman, M.; Fuentes, A.; et al. Reference Array and Design Consideration for the Next-Generation Event Horizon Telescope. Galaxies 2023, 11, 107. https://doi.org/10.3390/galaxies11050107
Doeleman SS, Barrett J, Blackburn L, Bouman KL, Broderick AE, Chaves R, Fish VL, Fitzpatrick G, Freeman M, Fuentes A, et al. Reference Array and Design Consideration for the Next-Generation Event Horizon Telescope. Galaxies. 2023; 11(5):107. https://doi.org/10.3390/galaxies11050107
Chicago/Turabian StyleDoeleman, Sheperd S., John Barrett, Lindy Blackburn, Katherine L. Bouman, Avery E. Broderick, Ryan Chaves, Vincent L. Fish, Garret Fitzpatrick, Mark Freeman, Antonio Fuentes, and et al. 2023. "Reference Array and Design Consideration for the Next-Generation Event Horizon Telescope" Galaxies 11, no. 5: 107. https://doi.org/10.3390/galaxies11050107
APA StyleDoeleman, S. S., Barrett, J., Blackburn, L., Bouman, K. L., Broderick, A. E., Chaves, R., Fish, V. L., Fitzpatrick, G., Freeman, M., Fuentes, A., Gómez, J. L., Haworth, K., Houston, J., Issaoun, S., Johnson, M. D., Kettenis, M., Loinard, L., Nagar, N., Narayanan, G., ... Wielgus, M. (2023). Reference Array and Design Consideration for the Next-Generation Event Horizon Telescope. Galaxies, 11(5), 107. https://doi.org/10.3390/galaxies11050107