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Accretion and Ejection Physics at High Time Resolution

F. M. Vincentelli, P. Casella, A. Veledina, A. Ambrifi, M. C. Baglio, D. Buckley, N. Castro Segura, Y. Cavecchi, D. de Martino, M. del Santo, P. Gandhi, G. Iliano, R. La Paca, C. Malacaria, A. Marino, K. O'Brien, N. Rea, A. Sanna, S. Scaringi, T. Shahbaz, L. Zampieri

TL;DR

Problem: accretion and ejection physics in compact-object binaries, focusing on inflow–outflow coupling at sub-second timescales. Approach: advocate a UV–to–mid-IR photon-counting timing facility with microsecond time-tagging and spectral resolution $R>5000$ to disentangle disc, jet, and wind components and measure inter-band delays, with emphasis on NS variability up to $\sim 100-1000\,\mathrm{Hz}$. Contributions: identifies two Open Science Questions for the 2040s—the innermost-region structure and jet/outflow radial profiles, and the universality of accretion–ejection in BHs and NSs—and outlines integration with 3D relativistic simulations and next-generation X-ray facilities. Significance: would tightly constrain jet speeds and launching radii, wind launching regions, and energy budgets, enabling a unified view of accretion across mass scales.

Abstract

Accretion onto compact objects is one of the most fundamental phenomena in the astrophysics, powering some of the most luminous objects in the sky. Along with this, accretion has also a key impact on the evolution of the Universe, through the launch of powerful outflows that affect the surrounding medium. In the last years sub-second optical-infrared observations of accreting X-ray binaries have opened a new window in the study of inflow-outflow connection, discovering a wide range of previously unkown phenomena. Here we review the key open questions in accretion and ejection physics and discuss how a dedicated facility, equipped with photon-counting detectors and high spectral resolution from the UV to the mid-infrared, can enable transformative advances in our understanding of accretion processes.

Accretion and Ejection Physics at High Time Resolution

TL;DR

Problem: accretion and ejection physics in compact-object binaries, focusing on inflow–outflow coupling at sub-second timescales. Approach: advocate a UV–to–mid-IR photon-counting timing facility with microsecond time-tagging and spectral resolution to disentangle disc, jet, and wind components and measure inter-band delays, with emphasis on NS variability up to . Contributions: identifies two Open Science Questions for the 2040s—the innermost-region structure and jet/outflow radial profiles, and the universality of accretion–ejection in BHs and NSs—and outlines integration with 3D relativistic simulations and next-generation X-ray facilities. Significance: would tightly constrain jet speeds and launching radii, wind launching regions, and energy budgets, enabling a unified view of accretion across mass scales.

Abstract

Accretion onto compact objects is one of the most fundamental phenomena in the astrophysics, powering some of the most luminous objects in the sky. Along with this, accretion has also a key impact on the evolution of the Universe, through the launch of powerful outflows that affect the surrounding medium. In the last years sub-second optical-infrared observations of accreting X-ray binaries have opened a new window in the study of inflow-outflow connection, discovering a wide range of previously unkown phenomena. Here we review the key open questions in accretion and ejection physics and discuss how a dedicated facility, equipped with photon-counting detectors and high spectral resolution from the UV to the mid-infrared, can enable transformative advances in our understanding of accretion processes.

Paper Structure

This paper contains 3 sections, 1 figure.

Table of Contents

  1. Introduction and Background
  2. Open Science Questions in the 2040s
  3. Technology and Data Handling Requirements

Figures (1)

  • Figure 1: Example of stochastic variability in $ugr$ filters for the accreting black hole X-ray binary V404 Cygni. Flux variations span a wide range of Fourier frequencies from milliseconds to hours. Statistical uncertainties are too small to discern. Variability strength changes from $u$ to $r$, allowing the underlying non-thermal processes in the vicinity of the compact object to be disentangled.