Scientific motivation of COLIBRI

Scientific motivation of COLIBRI

The forthcoming Sino-French SVOM mission will make an important contribution by improving our understanding of the GRB phenomenon and by allowing their use to understand the infancy of the Universe. It will also observe many other transient phenomena, as the tidal disruption events (TDEs) and supernovae shock breakouts, and will also search for the elusive sources of gravitational waves and highly energetic neutrinos.

SVOM is especially designed to achieve the best balance between space and ground instrumentation. The satellite instruments will permit the detection of the GRBs, their localization from arcminute to tens of arcseconds accuracy, and the study of the prompt and afterglow emission. The associated ground follow-up telescopes will obtain fast localization of the GRBs with sub-arcsecond precision, estimates of the redshift z by multi-band photometry, observations of prompt optical and infrared emission, and monitoring of the afterglow over days and weeks. One telescope will be in China and the other at the Observatorio Astronómico Nacional (OAN) of Mexico located in the Sierra de San Pedro Mártir (SPM) in Baja California. This last one is our COLIBRI!

COLIBRI in Mexico is especially important, as it will be the only one with the capability to observe in the infrared beyond 900 nm with good sensitivity. Thus, it will be the only one capable of detecting and monitoring high-redshift candidates beyond z = 6. It will be equipped with automated reduction and analysis systems that will be capable of delivering the localization and redshift estimate in less than five minutes. This will allow the most interesting GRBs (for example, ones at high redshift or that are highly extinguished) to be quickly observed with larger telescopes (NOT, NTT, VLT, GTC, etc.) to acquire, for example, a high-resolution spectrum to measure very precisely the redshift.

One notable feature of COLIBRI will be its ability to be able to point any source in the sky in less than 20 seconds, which is essential for studies of the first minutes of bursts, a domain that is still largely unexplored. In addition, this telescope will be able to observe simultaneously from the visible to the near infrared, and so will be especially important for observing high-redshift GRBs (z > 6) which occur during the first billion years of the Universe and dark GRB afterglows which constitute about 30% of bursts that are been detected for reasons that are still not completely clear.