skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Time Domain Filtering of Resolved Images of Sgr A{sup ∗}

Abstract

The goal of the Event Horizon Telescope (EHT) is to provide spatially resolved images of Sgr A*, the source associated with the Galactic Center black hole. Because Sgr A* varies on timescales that are short compared to an EHT observing campaign, it is interesting to ask whether variability contains information about the structure and dynamics of the accretion flow. In this paper, we introduce “time-domain filtering,” a technique to filter time fluctuating images with specific temporal frequency ranges and to demonstrate the power and usage of the technique by applying it to mock millimeter wavelength images of Sgr A*. The mock image data is generated from the General Relativistic Magnetohydrodynamic (GRMHD) simulation and the general relativistic ray-tracing method. We show that the variability on each line of sight is tightly correlated with a typical radius of emission. This is because disk emissivity fluctuates on a timescale of the order of the local orbital period. Time-domain filtered images therefore reflect the model dependent emission radius distribution, which is not accessible in time-averaged images. We show that, in principle, filtered data have the power to distinguish between models with different black-hole spins, different disk viewing angles, and different disk orientations in themore » sky.« less

Authors:
;  [1];  [2]
  1. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  2. Department of Physics, University of Illinois, 1110 West Green Street, Urbana, IL 61801 (United States)
Publication Date:
OSTI Identifier:
22663184
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 846; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; BLACK HOLES; DISTRIBUTION; EMISSION; EMISSIVITY; FILTERS; FREQUENCY RANGE; GALAXY NUCLEI; GRAVITATIONAL LENSES; MAGNETOHYDRODYNAMICS; RADIANT HEAT TRANSFER; RELATIVISTIC RANGE; SIMULATION; SPIN; STARS; TELESCOPES; WAVELENGTHS

Citation Formats

Shiokawa, Hotaka, Doeleman, Sheperd S., and Gammie, Charles F. Time Domain Filtering of Resolved Images of Sgr A{sup ∗}. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA82B7.
Shiokawa, Hotaka, Doeleman, Sheperd S., & Gammie, Charles F. Time Domain Filtering of Resolved Images of Sgr A{sup ∗}. United States. doi:10.3847/1538-4357/AA82B7.
Shiokawa, Hotaka, Doeleman, Sheperd S., and Gammie, Charles F. Fri . "Time Domain Filtering of Resolved Images of Sgr A{sup ∗}". United States. doi:10.3847/1538-4357/AA82B7.
@article{osti_22663184,
title = {Time Domain Filtering of Resolved Images of Sgr A{sup ∗}},
author = {Shiokawa, Hotaka and Doeleman, Sheperd S. and Gammie, Charles F.},
abstractNote = {The goal of the Event Horizon Telescope (EHT) is to provide spatially resolved images of Sgr A*, the source associated with the Galactic Center black hole. Because Sgr A* varies on timescales that are short compared to an EHT observing campaign, it is interesting to ask whether variability contains information about the structure and dynamics of the accretion flow. In this paper, we introduce “time-domain filtering,” a technique to filter time fluctuating images with specific temporal frequency ranges and to demonstrate the power and usage of the technique by applying it to mock millimeter wavelength images of Sgr A*. The mock image data is generated from the General Relativistic Magnetohydrodynamic (GRMHD) simulation and the general relativistic ray-tracing method. We show that the variability on each line of sight is tightly correlated with a typical radius of emission. This is because disk emissivity fluctuates on a timescale of the order of the local orbital period. Time-domain filtered images therefore reflect the model dependent emission radius distribution, which is not accessible in time-averaged images. We show that, in principle, filtered data have the power to distinguish between models with different black-hole spins, different disk viewing angles, and different disk orientations in the sky.},
doi = {10.3847/1538-4357/AA82B7},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 846,
place = {United States},
year = {2017},
month = {9}
}