The Final Decade II

Burrows, Donald

doi:10.1093/acprof:osobl/9780199737369.003.0015

Cited by 7 publications

(42 citation statements)

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“…This emission is likely generated in the shock interaction between the jet and the circumsource medium, in contrast to blazars in which the synchrotron emission is produced within the jet itself. Modelling of the radio emission indicates a start time of the initial event some 4 d prior to the time BAT triggered, in agreement with analysis of BAT data taken before the trigger occurred (Burrows et al 2011; Zauderer 2011).…”

Section: Introductionsupporting

confidence: 77%

“…Fits to the SED and time‐variable behaviour of Swift J164449.3+573451 performed at several different time‐slices and performed by different groups with independent data (Bloom et al 2011; Burrows et al 2011; Zauderer et al 2011) broadly agree on a number of key points: the SED consists of two prominent bumps, peaking roughly at millimetre and X‐ray/gamma‐ray frequencies; the X‐ray and radio emissions are formed in different regions; the presence of a collimated, relativistic jet; and the synchrotron nature of the long‐wavelength emission. An acceptable fit to the SED can be achieved with a model where the longer wavelength photons [i.e.…”

Section: Discussionmentioning

confidence: 99%

“…The second panel from the top that shows the 3σ limits on the linear polarization at 4.8 GHz (red, left‐hand vertical scale) and 1.4 GHz (cyan, right‐hand vertical scale), with the VLBA 8.4‐GHz limits added (open symbols, Levan et al 2011). The third panel from the top shows the infrared light curves in the J , H and K bands (red, green and blue squares, left‐hand vertical scale; photometry is not host subtracted), combining data reported in Levan et al (2011) and Burrows et al (2011) and additional data from Levan et al (in preparation). The red star shows the WHT K s ‐band polarimetry (right‐hand vertical scale).…”

Section: Observations and Data Analysismentioning

confidence: 99%

“…While initially thought to be an unusual gamma‐ray burst (GRB 110328A; Cummings et al 2011), prior detections by the Burst Alert Telescope (BAT) in addition to X‐ray behaviour highly atypical for GRBs (see e.g. Burrows et al 2011; Levan et al 2011) showed this source was likely of a different nature. Localization of a variable infrared and radio counterpart (Levan et al 2011; Zauderer et al 2011) spatially coincident with the nucleus of a galaxy at redshift z = 0.3543 (Levan et al 2011) further motivated a model in which the transient represents a sudden activation of a blazar‐like phenomenon, most likely fed by the tidal disruption of a (main‐sequence) star (Bloom et al 2011; Cannizzo, Troja & Lodato 2011; Krolik & Piran 2011), though it is difficult to rule out a completely novel phenomenon more closely related to standard GRBs (Woosley & Heger 2011; Quataert & Kasen 2012).…”

Section: Introductionmentioning

confidence: 99%

“…In this model, the sudden accretion on to the central massive black hole caused by a tidally disrupted star gives rise to a relativistic, beamed outflow whose light dominates over the light produced by the stellar disruption (Bloom et al 2011). The spectral energy distribution (SED) of the transient shows two prominent bumps (Bloom et al 2011; Burrows et al 2011; Zauderer 2011), which may be explained by the presence of synchrotron and inverse Compton emission processes (Aliu et al 2011; Bloom et al 2011; Burrows et al 2011). Constraints on the source size from radio spectra (Zauderer 2011) imply a relativistic jet as the source of the observed synchrotron emission, in agreement with fits to the source SED (Bloom et al 2011; Burrows et al 2011; Zauderer 2011).…”

Section: Introductionmentioning

confidence: 99%

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Polarimetry of the transient relativistic jet of GRB 110328/Swift J164449.3+573451

Wiersema

Horst

Levan

et al. 2012

Monthly Notices of the Royal Astronomical Society

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We present deep infrared (Ks‐band) imaging polarimetry and radio (1.4‐ and 4.8‐GHz) polarimetry of the enigmatic transient Swift J164449.3+573451. This source appears to be a short‐lived jet phenomenon in a galaxy at redshift z= 0.354, activated by a sudden mass accretion on to the central massive black hole, possibly caused by the tidal disruption of a star. We aim to find evidence for this scenario through linear polarimetry, as linear polarization is a sensitive probe of jet physics, source geometry and the various mechanisms giving rise to the observed radiation. We find a formal Ks‐band polarization measurement of Plin= 7.4 ± 3.5 per cent (including systematic errors). Our radio observations show continuing brightening of the source, which allows sensitive searches for linear polarization as a function of time. We find no evidence of linear polarization at radio wavelengths of 1.4 and 4.8 GHz at any epoch, with the most sensitive 3σ limits as deep as 2.1 per cent. These upper limits are in agreement with expectations from scenarios in which the radio emission is produced by the interaction of a relativistic jet with a dense circumsource medium. We further demonstrate how polarization properties can be used to derive properties of the jet in Swift J164449.3+573451, exploiting the similarities between this source and the afterglows of gamma‐ray bursts.

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Section: Introductionsupporting

confidence: 77%

Section: Discussionmentioning

confidence: 99%

Section: Observations and Data Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Polarimetry of the transient relativistic jet of GRB 110328/Swift J164449.3+573451

Wiersema

Horst

Levan

et al. 2012

Monthly Notices of the Royal Astronomical Society

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PTF10iya: a short-lived, luminous flare from the nuclear region of a star-forming galaxy

Cenko¹,

Bloom²,

Kulkarni³

et al. 2012

Monthly Notices of the Royal Astronomical Society

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We present the discovery and characterization of PTF10iya, a short‐lived (Δt≈ 10 d, with an optical decay rate of ∼0.3 mag d−1), luminous ( mag) transient source found by the Palomar Transient Factory. The ultraviolet/optical spectral energy distribution is reasonably well fitted by a blackbody with T≈ (1–2) × 104 K and peak bolometric luminosity LBB≈ (1–5) × 1044 erg s−1 (depending on the details of the extinction correction). A comparable amount of energy is radiated in the X‐ray band that appears to result from a distinct physical process. The location of PTF10iya is consistent with the nucleus of a star‐forming galaxy (z= 0.224 05 ± 0.000 06) to within 350 mas (99.7 per cent confidence radius), or a projected distance of less than 1.2 kpc. At first glance, these properties appear reminiscent of the characteristic ‘big blue bump’ seen in the near‐ultraviolet spectra of many active galactic nuclei (AGNs). However, emission‐line diagnostics of the host galaxy, along with a historical light curve extending back to 2007, show no evidence for AGN‐like activity. We therefore consider whether the tidal disruption of a star by an otherwise quiescent supermassive black hole may account for our observations. Though with limited temporal information, PTF10iya appears broadly consistent with the predictions for the early ‘super‐Eddington’ phase of a solar‐type star being disrupted by a ∼107 M⊙ black hole. Regardless of the precise physical origin of the accreting material, the large luminosity and short duration suggest that otherwise quiescent galaxies can transition extremely rapidly to radiate near the Eddington limit; many such outbursts may have been missed by previous surveys lacking sufficient cadence.

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Afterglow model for the radio emission from the jetted tidal disruption candidate Swift J1644+57

Metzger

Giannios

Mimica

2012

Monthly Notices of the Royal Astronomical Society

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The recent transient event Swift J1644+57 has been interpreted as emission from a collimated relativistic jet, powered by the sudden onset of accretion on to a supermassive black hole following the tidal disruption of a star. Here we model the radio-microwave emission as synchrotron radiation produced by the shock interaction between the jet and the gaseous circumnuclear medium (CNM). At early times after the onset of the jet (t 5-10 d) a reverse shock propagates through and decelerates the ejecta, while at later times the outflow approaches the Blandford-McKee self-similar evolution (possibly modified by additional late energy injection). The achromatic break in the radio light curve of Swift J1644+57 is naturally explained as the transition between these phases. We show that the temporal indices of the pre-and post-break light curve are consistent with those predicted if the CNM has a wind-type radial density profile n ∝ r −2 . The observed synchrotron frequencies and self-absorbed flux constrain the fraction of the post-shock thermal energy in relativistic electrons e ≈ 0.03-0.1, the CNM density at 10 18 cm n 18 ≈ 1-10 cm −3 and the initial Lorentz factor j ≈ 10-20 and opening angle θ j ∼ (0.3-1) −1 j ∼ 0.01-0.1 of the jet. Radio modelling thus provides robust independent evidence for a narrowly collimated outflow. Extending our model to the future evolution of Swift J1644+57, we predict that the radio flux at low frequencies (ν few GHz) will begin to brighten more rapidly once the characteristic frequency ν m crosses below the radio band after it decreases below the self-absorption frequency on a time-scale of months (indeed, such a transition may already have begun). Our results demonstrate that relativistic outflows from tidal disruption events provide a unique probe of the conditions in distant, previously inactive galactic nuclei, complementing studies of normal active galactic nuclei.

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The Final Decade II

Cited by 7 publications

References 0 publications

Polarimetry of the transient relativistic jet of GRB 110328/Swift J164449.3+573451

Polarimetry of the transient relativistic jet of GRB 110328/Swift J164449.3+573451

PTF10iya: a short-lived, luminous flare from the nuclear region of a star-forming galaxy

Afterglow model for the radio emission from the jetted tidal disruption candidate Swift J1644+57

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