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Title: RADIO MONITORING OF THE TIDAL DISRUPTION EVENT SWIFT J164449.3+573451. II. THE RELATIVISTIC JET SHUTS OFF AND A TRANSITION TO FORWARD SHOCK X-RAY/RADIO EMISSION

Abstract

We present continued multi-frequency radio observations of the relativistic tidal disruption event Swift J164449.3+573451 (Sw 1644+57) extending to t Almost-Equal-To 600 days. The data were obtained with the JVLA and AMI Large Array as part of our on-going study of the jet energetics and the density structure of the parsec-scale environment around the disrupting supermassive black hole. We combine these data with public Swift/XRT and Chandra X-ray observations over the same time-frame to show that the jet has undergone a dramatic transition starting at Almost-Equal-To 500 days, with a sharp decline in the X-ray flux by about a factor of 170 on a timescale of {delta}t/t {approx}< 0.2 (and by a factor of 15 in {delta}t/t Almost-Equal-To 0.05). The rapid decline rules out a forward shock origin (direct or reprocessing) for the X-ray emission at {approx}< 500 days, and instead points to internal dissipation in the inner jet. On the other hand, our radio data uniquely demonstrate that the low X-ray flux measured by Chandra at Almost-Equal-To 610 days is consistent with emission from the forward shock. Furthermore, the Chandra data are inconsistent with thermal emission from the accretion disk itself since the expected temperature of {approx}30-60 eV and innermore » radius of {approx}2-10 R{sub s} cannot accommodate the observed flux level or the detected emission at {approx}> 1 keV. We associate the rapid decline with a turn off of the relativistic jet when the mass accretion rate dropped below {approx} M-dot{sub Edd}{approx}0.006 M{sub Sun} yr{sup -1} (for a 3 Multiplication-Sign 10{sup 6} M{sub Sun} black hole and order unity efficiency) indicating that the peak accretion rate was about 330 M-dot{sub Edd}, and the total accreted mass by t Almost-Equal-To 500 days is about 0.15 M{sub Sun }. From the radio data we further find significant flattening in the integrated energy of the forward shock at t {approx}> 250 days with E{sub j,iso} Almost-Equal-To 2 Multiplication-Sign 10{sup 54} erg (E{sub j} Almost-Equal-To 10{sup 52} erg for a jet opening angle, {theta}{sub j} = 0.1) following a rise by about a factor of 15 at Almost-Equal-To 30-250 days. Projecting forward, we predict that the emission in the radio and X-ray bands will evolve in tandem with similar decline rates.« less

Authors:
; ; ;  [1];  [2];  [3];  [4];  [5]
  1. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  2. Mullard Radio Observatory, Cavendish Laboratory, Cambridge, CB3 0HE (United Kingdom)
  3. Racah Institute of Physics, Hebrew University, 91904 Jerusalem (Israel)
  4. Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany)
  5. Department of Physics and Astronomy, York University, Toronto, Ontario (Canada)
Publication Date:
OSTI Identifier:
22126869
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 767; Journal Issue: 2; 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; 36 MATERIALS SCIENCE; ACCRETION DISKS; BLACK HOLES; DENSITY; EFFICIENCY; EMISSION; MONITORING; PEAKS; RELATIVISTIC RANGE; X RADIATION

Citation Formats

Zauderer, B. A., Berger, E., Margutti, R., Soderberg, A. M., Pooley, G. G., Sari, R., Brunthaler, A., and Bietenholz, M. F. RADIO MONITORING OF THE TIDAL DISRUPTION EVENT SWIFT J164449.3+573451. II. THE RELATIVISTIC JET SHUTS OFF AND A TRANSITION TO FORWARD SHOCK X-RAY/RADIO EMISSION. United States: N. p., 2013. Web. doi:10.1088/0004-637X/767/2/152.
Zauderer, B. A., Berger, E., Margutti, R., Soderberg, A. M., Pooley, G. G., Sari, R., Brunthaler, A., & Bietenholz, M. F. RADIO MONITORING OF THE TIDAL DISRUPTION EVENT SWIFT J164449.3+573451. II. THE RELATIVISTIC JET SHUTS OFF AND A TRANSITION TO FORWARD SHOCK X-RAY/RADIO EMISSION. United States. https://doi.org/10.1088/0004-637X/767/2/152
Zauderer, B. A., Berger, E., Margutti, R., Soderberg, A. M., Pooley, G. G., Sari, R., Brunthaler, A., and Bietenholz, M. F. 2013. "RADIO MONITORING OF THE TIDAL DISRUPTION EVENT SWIFT J164449.3+573451. II. THE RELATIVISTIC JET SHUTS OFF AND A TRANSITION TO FORWARD SHOCK X-RAY/RADIO EMISSION". United States. https://doi.org/10.1088/0004-637X/767/2/152.
@article{osti_22126869,
title = {RADIO MONITORING OF THE TIDAL DISRUPTION EVENT SWIFT J164449.3+573451. II. THE RELATIVISTIC JET SHUTS OFF AND A TRANSITION TO FORWARD SHOCK X-RAY/RADIO EMISSION},
author = {Zauderer, B. A. and Berger, E. and Margutti, R. and Soderberg, A. M. and Pooley, G. G. and Sari, R. and Brunthaler, A. and Bietenholz, M. F.},
abstractNote = {We present continued multi-frequency radio observations of the relativistic tidal disruption event Swift J164449.3+573451 (Sw 1644+57) extending to t Almost-Equal-To 600 days. The data were obtained with the JVLA and AMI Large Array as part of our on-going study of the jet energetics and the density structure of the parsec-scale environment around the disrupting supermassive black hole. We combine these data with public Swift/XRT and Chandra X-ray observations over the same time-frame to show that the jet has undergone a dramatic transition starting at Almost-Equal-To 500 days, with a sharp decline in the X-ray flux by about a factor of 170 on a timescale of {delta}t/t {approx}< 0.2 (and by a factor of 15 in {delta}t/t Almost-Equal-To 0.05). The rapid decline rules out a forward shock origin (direct or reprocessing) for the X-ray emission at {approx}< 500 days, and instead points to internal dissipation in the inner jet. On the other hand, our radio data uniquely demonstrate that the low X-ray flux measured by Chandra at Almost-Equal-To 610 days is consistent with emission from the forward shock. Furthermore, the Chandra data are inconsistent with thermal emission from the accretion disk itself since the expected temperature of {approx}30-60 eV and inner radius of {approx}2-10 R{sub s} cannot accommodate the observed flux level or the detected emission at {approx}> 1 keV. We associate the rapid decline with a turn off of the relativistic jet when the mass accretion rate dropped below {approx} M-dot{sub Edd}{approx}0.006 M{sub Sun} yr{sup -1} (for a 3 Multiplication-Sign 10{sup 6} M{sub Sun} black hole and order unity efficiency) indicating that the peak accretion rate was about 330 M-dot{sub Edd}, and the total accreted mass by t Almost-Equal-To 500 days is about 0.15 M{sub Sun }. From the radio data we further find significant flattening in the integrated energy of the forward shock at t {approx}> 250 days with E{sub j,iso} Almost-Equal-To 2 Multiplication-Sign 10{sup 54} erg (E{sub j} Almost-Equal-To 10{sup 52} erg for a jet opening angle, {theta}{sub j} = 0.1) following a rise by about a factor of 15 at Almost-Equal-To 30-250 days. Projecting forward, we predict that the emission in the radio and X-ray bands will evolve in tandem with similar decline rates.},
doi = {10.1088/0004-637X/767/2/152},
url = {https://www.osti.gov/biblio/22126869}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 767,
place = {United States},
year = {Sat Apr 20 00:00:00 EDT 2013},
month = {Sat Apr 20 00:00:00 EDT 2013}
}