Ultra-long MeV transient from a relativistic jet: a tidal disruption event candidate
arXiv:2507.18694 · doi:10.1051/0004-6361/202556591
Abstract
On July 2, 2025, the Gamma-ray Burst Monitor (GBM) onboard the Fermi Gamma-ray space telescope detected three short-duration MeV transients with overlapping sky locations. These events, named as GRB 250702D, B, and E (collectively referred to as DBE), triggered the detector with delays of approximately 1-2 hours between each burst. Follow-up observations of this unusually long MeV transient (lasting >3 hours) by the Neil Gehrels Swift Observatory and the Nuclear Spectroscopic Telescope Array over a period of 10 days revealed a steep temporal decline in soft X-rays (). The time-averaged spectra during the outbursts are well described by a single power law , while upper limits above 100 MeV imply a spectral cutoff between 10 MeV and 100 MeV. Using standard gamma-ray transparency arguments, we derive a lower limit on the bulk Lorentz factor. Combined with the steep decline in X-rays, these constraints point to a relativistic jet origin. The properties of DBE are inconsistent with established GRB spectral-energy correlations, disfavoring classical long GRB progenitors. Instead, the basic characteristics of DBE resemble those of previously reported jetted tidal disruption events (TDEs), though alternative progenitor channels cannot be excluded. In the relativistic TDE scenario, DBE is the first one with detected MeV gamma-ray emission. We argue that the observed emission is most likely produced by synchrotron radiation from sub-TeV electrons.
arXiv commentAccepted for publication in A&A (Letter)
References in corpus (22)
- The Nuclear Spectroscopic Telescope Array (NuSTAR) Mission
- The Fermi Gamma-Ray Burst Monitor
- Gamma-Ray Bursts and the Fireball Model
- Intrinsic spectra and energetics of BeppoSAX Gamma-Ray Bursts with known redshifts
- Optical and Long Wavelength Afterglow from Gamma-Ray Bursts
- GRB Formation Rates inferred from the Spectral Peak Energy - Luminosity Relation
- A relativistic jetted outburst from a massive black hole fed by a tidally disrupted star
- Discovery of the Onset of Rapid Accretion by a Dormant Massive Black Hole
- How to Tell a Jet from a Balloon: A Proposed Test for Beaming in Gamma Ray Bursts
- Optimal binning of X-ray spectra and response matrix design
- Lower Limits on Lorentz Factors in Gamma Ray Bursts
- Swift J2058.4+0516: Discovery of a Possible Second Relativistic Tidal Disruption Flare?
- An extremely luminous panchromatic outburst from the nucleus of a distant galaxy
- A complete sample of bright Swift Long Gamma Ray Bursts: testing the spectral-energy correlations
- Swift J1112.2-8238: A Candidate Relativistic Tidal Disruption Flare
- A very luminous jet from the disruption of a star by a massive black hole
- Swift J1644+57: A White Dwarf Tidally Disrupted by a 10^4 M_{odot} Black Hole?
- A Multiwavelength Study of the Relativistic Tidal Disruption Candidate Sw J2058+05 at Late Times
- The Birth of a Relativistic Jet Following the Disruption of a Star by a Cosmological Black Hole
- Swift J1644+57 as an off-axis Jet
- A Physical Background Model for the Fermi Gamma-ray Burst Monitor
- Insights into the physics of GRBs from the high-energy extension of their prompt emission spectra