J/ApJ/817/103 Definitive Swift/XRT LC of Swift J164449.3+573451 (Mangano+, 2016)
The definitive X-ray light curve of Swift J164449.3+573451.
Mangano V., Burrows D.N., Sbarufatti B., Cannizzo J.K.
<Astrophys. J., 817, 103 (2016)>
=2016ApJ...817..103M 2016ApJ...817..103M (SIMBAD/NED BibCode)
ADC_Keywords: X-ray sources
Keywords: accretion, accretion disks; black hole physics; galaxies: active;
galaxies: jets; X-rays: galaxies;
X-rays: individual: Swift J164449.3+573451
Abstract:
On 2011 March 28, the Swift Burst Alert Telescope triggered on an
object that had no analog in over six years of Swift operations.
Follow-up observations by the Swift X-ray Telescope (XRT) found a new,
bright X-ray source covering three orders of magnitude in flux over
the first few days, that was much more persistent (and variable) than
gamma-ray burst afterglows. Ground-based spectroscopy found a redshift
of 0.35, implying extremely high luminosity, with integrated
isotropic-equivalent energy output in the X-ray band alone exceeding
1053erg in the first two weeks after discovery. Strong evidence for
a collimated outflow or beamed emission was found. The observational
properties of this object are unlike anything ever before observed. We
interpret these unique properties as the result of emission from a
relativistic jet produced in the aftermath of the tidal disruption of
a main sequence star by a massive black hole (BH) in the center of the
host galaxy. The source decayed slowly as the stellar remnants were
accreted onto the BH, before abruptly shutting off. Here we present
the definitive XRT team light curve for Swift J164449.3+573451 and
discuss its implications. We show that the unabsorbed flux decayed
roughly as a t-1.5 power law up to 2012 August 17. The steep turnoff
of an order of magnitude in 24 hr seems to be consistent with the
shutdown of the jet as the accretion disk transitioned from a thick
disk to a thin disk. Swift continues to monitor this source in case
the jet reactivates.
Description:
Swift J164449.3+573451 triggered the Swift/BAT twice on 2011 March
28th, resulting in automated observations by Swift/XRT. The whole
Swift follow-up and monitoring campaign of Swift J1644+57 from
discovery up to three years later consists of ∼700 sequences and four
different trigger numbers: 450158 (seq. 0-7, from 2011 March 28 to
30), 31955 (seq. 2-255, from 2011 March 31 to December 06), 32200
(seq. 1-237, from 2011 December 07 to 2012 August 15), and 32526 (seq.
1-200, from 2012 August 16 to 2014 March 28). The total XRT exposure
in the data set is 2Ms in Photon Counting (PC) mode and 320ks in
Windowed Timing (WT) mode.
We also re-analyze the 24.7ks Chandra-ACIS ToO observation (PI:
Tanvir), performed on 2012 November 26, and present analysis results
for a second ACIS observation of 27.7ks exposure performed by Chandra
on 2015 February 17 (PI: Levan).
We present the definitive Swift/XRT light curve for Swift J1644+57,
which spans ∼800days.
Objects:
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RA (ICRS) DE Designation(s)
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16 44 49 +57 34.9 Swift J164449.3+573451 = GRB 110328A
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 91 216 Swift J164449.3+573451: best fit parameters of
time-resolved spectra
table2.dat 49 6139 Swift J164449.3+573451 X-ray light curve
table3.dat 32 98 Swift J164449.3+573451: good time interval (GTI)
of the dips
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See also:
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq Running sequence number
5 A1 --- f_Seq [e] e = Spectrum of the post-drop phase
7- 8 A2 --- XRT Swift/XRT mode identifier (G1)
10- 21 F12.8 d Start Starting time of data interval (G2)
23- 35 F13.8 d Stop Stopping time of data interval (G2)
37- 39 F3.1 10+22/cm2 NH [0.8/3.1] Hydrogen column density
41- 43 F3.1 10+22/cm2 E_NH Upper uncertainty in NH
45- 47 F3.1 10+22/cm2 e_NH Lower uncertainty in NH
49- 53 F5.2 --- Index [-0.2/4.4] Photon index (1)
55- 58 F4.2 --- E_Index Upper uncertainty in Index
60- 63 F4.2 --- e_Index Lower uncertainty in Index
65- 69 F5.2 --- beta [-1.6/2]? The Β value
71- 74 F4.2 --- E_beta ? Upper uncertainty in beta
76- 79 F4.2 --- e_beta ? Lower uncertainty in beta
81- 87 F7.3 --- chi2 [3.7/470] The χ2 value
89- 91 I3 --- DoF [9/470] Degrees of Freedom
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Note (1): This is the value of the α parameter when a value is given
in the beta column.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 12 F12.8 d Start Starting time of data interval (G2)
14- 26 F13.8 d Stop Stopping time of data interval (G2)
28- 36 E9.3 mW/m2 Flux Swift/XRT flux (0.3-10keV; unabsorbed)
in erg/s/cm^2
38- 46 E9.3 mW/m2 e_Flux Uncertainty in Flux
48- 49 A2 --- XRT Swift/XRT mode identifier (G1)
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq Running sequence number
5- 16 F12.8 d Start Starting time of data interval (G2)
18- 29 F12.8 d Stop Stopping time of data interval (G2)
31- 32 A2 --- XRT Swift/XRT mode identifier (G1)
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Global notes:
Note (G1): Swift/XRT mode as follows:
PC = Photon Counting
WT = Windowed Timing
See Burrows et al. 2005SSRv..120..165B 2005SSRv..120..165B, for a description of
the XRT instrument modes.
Note (G2): Relative to the first BAT trigger at
T0=2011-03-28 12:57:45.201 UTC=55648.5401 MJD.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 08-Apr-2016