VLBA25A-312
Continued Radio Monitoring of Sgr A* with the 2025 EHT Multiwavelength Campaign
Abstract
In May 2022, the Event Horizon Telescope (EHT) Collaboration revealed its first image of the Galactic supermassive black hole, Sgr A*. Ongoing efforts have focused on multiwavelength studies of its hourly-timescale variability (flares) between radio and X-ray wavelengths. Recent advances now allow for higher frequency EHT observations up to 345 GHz, and the launch of JWST in the past few years has begun to illuminate this broader multiwavelength picture, particularly at submm frequencies and higher. Radio observations are crucial to understanding the evolution of the flares over several hours, which is impossible at higher frequencies, where the synchrotron cooling lifetimes are shorter. Combined with higher-energy constraints from quasi-simultaneous submm, IR, and X-ray observations, this complete multiwavelength approach will characterize the electron spectrum across all energies responsible for producing the flares. We propose four simultaneous full-track VLA/VLBA+GBT observations with the planned 2025 EHT Multiwavelength Campaign, which will include submm (SMA/ALMA/NOEMA), IR (JWST/MIRI), and X-ray (Chandra/NuSTAR) counterparts. GBT observations are requested to acquire fringes to all antennas, particularly at 86 GHz. These data will constrain the flares' physical properties, including their initial production and expansion. These panchromatic observations will place strong priors on models consistent with the event horizon image and interpretation.
Investigators
| Name | Institution |
|---|---|
| Ramprasad Rao | Center for Astrophysics | Harvard & Smithsonian |
| Mark Gurwell | Center for Astrophysics | Harvard & Smithsonian |
| Garrett Keating | California at Berkeley, University of; Harvard-Smithsonian Center for Astrophysics |
| Howard Smith | Center for Astrophysics | Harvard & Smithsonian |
| Giovanni Fazio | Center for Astrophysics | Harvard & Smithsonian |
| Bart Ripperda | Toronto, University of |
| Steven Willner | Center for Astrophysics | Harvard & Smithsonian |
| Joseph Hora | Center for Astrophysics | Harvard & Smithsonian |
| Sebastiano von Fellenberg | Max-Planck-Institut für Radioastronomie |
| Gunther Witzel | California at Los Angeles, University of; Max-Planck-Institut für Radioastronomie |
| Thomas Krichbaum | Max-Planck-Institut für Radioastronomie |
| Venkatessh Ramakrishnan | Turku, University of |
| Rocco Lico | Istituto Nazionale di Astrofisica; Max-Planck-Institut für Radioastronomie; Andalucía, Instituto de Astrofísica de |
| Jae-Young Kim | Max-Planck-Institut für Radioastronomie; Kyungpook National University |
| Shuo Zhang | Massachusetts Institute of Technology |
| Sunil Chandra | North-West University |
| Michael Johnson | California at Santa Barbara, University of; Center for Astrophysics | Harvard & Smithsonian |
| Mislav Balokovic | California Institute of Technology |
| Michael Nowak | Washington University in St. Louis |
| Joseph Neilsen | Villanova University |
| Daryl Haggard | McGill University |
| Kazuhiro Hada | Istituto Nazionale di Astrofisica; National Astronomical Observatory of Japan ; Nagoya City University |
| Sera Markoff | Amsterdam, Universiteit van |
| Geoffrey Bower | Academia Sinica |
| Joseph Michail * | Center for Astrophysics | Harvard & Smithsonian |
* indicates the PI