EP240414a: Off-axis View of a Jet-Cocoon System from an Expanded Progenitor Star

Abstract

When a relativistic jet is launched following the core-collapse of a star, its interaction with the stellar envelope leads to the formation of a hot cocoon, which produces various viewing-angle-dependent observational phenomena following the breakout from the surface. We study the observational signatures of fast X-ray transient (FXT) EP240414a, which may originate from a jet-cocoon system viewed slightly off-axis. In our model, (1) the prompt X-ray emission lasting $\sim 100\mathrm{s}$ is attributed to the cooling emission from the inner cocoon (shocked jet material); (2) the $\sim 0.1\mathrm{d}$ X-ray emission comes from the inner cocoon's afterglow; (3) the $\sim 0.4\mathrm{d}$ thermal-dominated optical emission arises from the cooling of the outer cocoon (shocked stellar material); (4) the $\sim 3\mathrm{d}$ non-thermal optical component and subsequent radio emission can be explained by the afterglow from a jet with a viewing angle of $10^{\circ }\lesssim {\theta }_{\mathrm{v}}\lesssim 15^{\circ }$; and (5) the associated broad-lined Type Ic supernova only dominates the optical emission after $\sim 7\mathrm{d}$. Both the jet inferred from the off-axis afterglow and the inner cocoon constrained by the cooling emission are found to have similar kinetic energies, on the order of $10^{51}\mathrm{erg}$. We find that the progenitor's radius is $\sim 3R_{\odot }$ as constrained by the { inner cocoon's} cooling emissions, indicating that the pre-explosion star may be a massive helium star that is slightly inflated. More FXTs associated with off-axis jets and supernovae will be further examined by the Einstein Probe, leading to a deeper understanding of jet-cocoon systems.

arXiv comment16 pages, 5 figures, 1 table. Revised version, first submitted on March 1st

References in corpus (56)

• Collapsars - Gamma-Ray Bursts and Explosions in "Failed Supernovae"
• Discovery of the peculiar supernova 1998bw in the error box of GRB980425
• The Supernova -- Gamma-Ray Burst Connection
• Jets in GRBs
• The Physics of Gamma-Ray Bursts and Relativistic Jets
• The Dynamics and Light Curves of Beamed Gamma Ray Burst Afterglows
• Nearby Supernova Rates from the Lick Observatory Supernova Search. III. The Rate-Size Relation, and the Rates as a Function of Galaxy Hubble Type and Colour
• The Expanded Very Large Array -- a New Telescope for New Science
• Relativistic Jets in Collapsars
• Early supernovae light-curves following the shock-breakout
• Wave-Driven Mass Loss in the Last Year of Stellar Evolution: Setting the Stage for the Most Luminous Core-Collapse Supernovae
• The propagation of relativistic jets in external media
• TeV Neutrinos from Successful and Choked Gamma-Ray Bursts
• Gamma-Ray Bursts and Type Ic Supernovae: SN 1998bw
• Events in the life of a cocoon surrounding a light, collapsar jet
• Overall Evolution of Jetted Gamma-ray Burst Ejecta
• Multi-Wavelength Afterglows in Gamma-Ray Bursts: Refreshed Shock and Jet Effects
• A Complete Reference of the Analytical Synchrotron External Shock Models of Gamma-Ray Bursts
• Relativistic MHD simulations of core-collapse GRB jets: 3D instabilities and magnetic dissipation
• Pre-Supernova Outbursts via Wave Heating in Massive Stars I: Red Supergiants
• Supernova Hosts for Gamma-Ray Burst Jets: Dynamical Constraints
• Relativistic shock breakouts - a variety of gamma-ray flares: from low luminosity gamma-ray bursts to type Ia supernovae
• The Observable Signatures of GRB Cocoons
• Revisiting the Lick Observatory Supernova Search Volume-Limited Sample: Updated Classifications and Revised Stripped-Envelope Supernova Fractions
• Formation rates of core collapse SNe and GRBs
• A unified picture for low-luminosity and long gamma-ray bursts based on the extended progenitor of llgrb 060218/SN 2006aj
• Failed gamma-ray bursts and orphan afterglows
• Signatures of a jet cocoon in early spectra of a supernova associated with a $\gamma$-ray burst
• The Einstein Probe Mission
• The Collimation and Energetics of the Brightest Swift Gamma-Ray Bursts
• A Unified Jet Model of X-Ray Flashes, X-Ray-Rich Gamma-Ray Bursts, and Gamma-Ray Bursts: I. Power-Law-Shaped Universal and Top-Hat-Shaped Variable Opening-Angle Jet Models
• The structure of hydrodynamic $\gamma$-ray burst jets
• A Redshift Determination for XRF 020903: First Spectroscopic Observations of an X-Ray Flash
• Afterglow emission in Gamma-Ray Bursts: I. Pair-enriched ambient medium and radiative blast waves
• The Ultimate Light Curve of SN 1998bw/GRB 980425
• Gamma-ray burst progenitors
• A Diversity of Wave-driven Pre-supernova Outbursts
• X-ray Plateaus in Gamma Ray Bursts' light-curves from jets viewed slightly off-axis
• Observational constraints on the structure of gamma-ray burst jets
• The spins of compact objects born from helium stars in binary systems
• Shock Cooling Emission from Extended Material Revisited
• Optical measurement of superluminal motion in the neutron-star merger GW170817
• Dirty Fireballs and Orphan Afterglows: A Tale of Two Transients
• Radio observations of a sample of broad-lined type Ic supernovae discovered by PTF/iPTF: A search for relativistic explosions
• SN2020bvc: a Broad-lined Type Ic Supernova with a Double-peaked Optical Light Curve and a Luminous X-ray and Radio Counterpart
• Shocked jets in CCSNe can power the zoo of fast blue optical transients
• Thermal and non-thermal emission from the cocoon of a gamma-ray burst jet
• The broad-line type Ic SN 2020bvc: signatures of an off-axis gamma-ray burst afterglow
• On the opening angle of magnetised jets from neutron-star mergers: the case of GRB170817A
• Cosmological Fast Optical Transients with the Zwicky Transient Facility: A Search for Dirty Fireballs
• Transparent Helium in Stripped Envelope Supernovae
• Radio emission from the cocoon of a GRB jet: implications for relativistic supernovae and off-axis GRB emission
• A Beaming-Independent Estimate of the Energy Distribution of Long Gamma-Ray Bursts: Initial Results and Future Prospects
• A Narrow Uniform Core with a Wide Structured Wing: Modeling the TeV and Multi-wavelength Afterglows of GRB 221009A
• The Expanded Giant Metrewave Radio Telescope
• Magnetars, Gamma-ray Bursts, and Very Close Binaries

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