University Nijmegen) Heino Falcke, Glennys Farrar, Joseph Gelfand, Suvi Gezari, David Hogg, Elmar Körding, Nidia Morrell, Linda Östman, Dennis Zaritsky TKSP Meeting, June 28, 2011, Amsterdam
for astrophysics • Rare events: once every 104-5 per year per black hole (eg, Wang & Merritt 2004) • Few found in X-ray and UV surveys (eg, Komossa+ 2002; Gezari+ 2008) • Recently found in at optical wavelengths (van Velzen+ 2010; Drake+ 2011, Cenko+ 2011) • Expect 10 (PTF, PanStarrs) to 1000 (LSST) per year 3
radio detections, yet • Accretion <--> Jets • Just like X-ray binaries (!) (eg, Fender+ 2004) • Let’s build a model: simple, conservative, empirical ‣ Synchrotron emission from jet core ‣ But coherent emission will be awesome 4
(Fender et al. 2004). In the quiescent mode (the hard-state) and during the onset of the burst, jets in X-ray binaries are radio-loud, while in the high-accretion mode (the soft-state) they are radio-quiet. The sudden enhancement of the accretion rate during a TDE, may move it through the different modes of accretion in two ways: directly into the radio-quiet soft-state, or into the soft-state via the radio-loud burst-state. Alternatively, the jet from a TDE may behave like a radio loud quasar at all times. We therefore consider three different scenarios for the fraction of accretion energy that is fed into the jet: qj = 0.2 all times (a) 2 × 10−3 ˙ M(t) > 2% ˙ M Edd (b) 0.2 t < t fallback (c) . (4) were each scenario reverts to the preceding one if the con- dition on t or ˙ M is not true (e.g., qj = 0.2 if ˙ M < 2% ˙ M Edd (Falcke & Biermann 1995; Körding+ 2008) 280 E. G. K¨ ording, S. Jester and R. Fender 21 22 23 24 25 26 27 28 29 I M − 24.5 25.0 25.5 26.0 26.5 27.0 27.5 28.0 28.5 29.0 z H M 4 7 ] r s / z H / W [ L g o L Figure 2. Normalizing the jet power measures from radio luminosities with sources of measured jet powers. On the ordinate (y-axis) we plot the 74- MHz radio luminosity and on the abscissa (x-axis) we give the absolute i-band magnitude. The line represents the linear relation fitted to the data (see text). Survey (VLSS1; Cohen et al. 2006, 2007a) using a matching ra- dius of 20 arcsec (the histogram of radial separations between the closest matched sources has a local minimum at this matching ra- dius). We use 74-MHz fluxes as this frequency is near the target of 151 MHz, especially for the large number of the quasars around Pjet Ljet Lν ∝ (qjLd )17/12 (Rees 1989) ˙ M(t) ∝ t−5/3
Over 46 Telegrams & Circulars • 5 GHz detection 2 days after Swift trigger (EVLA) • 1.7 mJy @ 8.4 GHz (VLBI) • 15 mJy @ 98 GHz (CARMA) 8 credit: HST NASA Birth of a Relativistic Outflow in Swift J164449.3+573451 109 1010 1011 1012 1013 1014 1015 1016 1017 1018 1040 1041 1042 1043 1044 1045 1046 1047 1048 2011 March 30 UT 2011 April 4 UT 2011 April 9 UT 2011 April 16 UT BL Lac Rest Frequency (Hz) !L ! (erg/s) Figure 2. Spectral energy distributions (SEDs) of Swift J164449.3+573451 from radio to X-ray (Zauderer+ 2011)
Do MSSS twice ... • Use optical data: SDSS photometric galaxies ‣ over 14,000 sq degree (208,478,448 galaxies) ‣ median z~0.5 ‣ 0.1% match to FIRST (1.4 GHz, ~10,000 sq. degree) (Ivezic+ 2002) ‣ Interesting if detected at >30 mJy in LOFAR but not detected in FIRST 12 GMRT Bootes field (Intema PhD thesis)
we integrate using only the photons that will arrive simultaneously at the observer, tr (t, z) = t−z cos(i) c−1 with i the angle between the jet and observer, in the rest-frame of the jet. Note that for observed angles cos(i obs ) < βj , we have tr > t; the photons from the middle of the jet arrive simultaneous with photons emitted further ahead, i.e., the jet appears to be seen from behind in the observer frame; we refer to Jester (2008) for a detailed discussion of retardation in jets. While in the classic jet model the value of z ssa is ab- sorbed into the normalization (C eq ), for the time-variable model it sets the timescale of emission and thus needs to be determined. From τ ∝ zκ syn / sin(i) = 1, where κ syn ∝ B4 is the synchrotron emission coefficient, we get z ssa = 1 pc f GHz ν/δ qj (t) 0.2 Ld (t) 1045 erg s−1 2 3 βj sin( i 30 ◦ ) 5 γj 1 3 (3) (FB95, Eq. 52), with γj the Lorentz factor of the jet and f ∼ 1, is a factor that dependents on the details of equipar- tition. We preform a check on the latter using observations zdec ∼ 10 pc qj 0.2 Ld 1045 erg s−1 1/3 Lν (t) = C eq δ2 zdec 0 dz z2 syn (tr, z, ν/δ)Θ ssa (tr, z, ν/δ) .(2) Here Θ ssa (t, z, ν) is a step function that enforces a crude radiative transfer: it is zero for z < z ssa (t) and unity for z > z ssa (t). The retarded time, tr , is introduced to ensure that we integrate using only the photons that will arrive simultaneously at the observer, tr (t, z) = t−z cos(i) c−1 with i the angle between the jet and observer, in the rest-frame of the jet. Note that for observed angles cos(i obs ) < βj , we have tr > t; the photons from the middle of the jet arrive simultaneous with photons emitted further ahead, i.e., the jet appears to be seen from behind in the observer frame; we
4 SNAPSHOT RATE Using the model presented in section 2, we can predict how many jets are visible above a certain flux limit (F lim ) at any moment in time, N(F lim , ν) = (4π)−1 ˙ N tde dΩ obs dz 4πd2 C (z) × dM BH φ BH τ eff (Lν , dL (z), F lim ) . (5) Here dC (z) and dL (z) are the co-moving and luminosity dis- tance1, respectively and φ BH is the black hole mass function. The integration over viewing angles, dΩ obs , accounts for the effects of Doppler boosting. Finally, our jet model enters via τ eff (Lν (M BH , i obs ), dL, F lim ) or the “effective time” given by the part of the light curve that obeys Lν (t)/(4πd2 L ) > F lim . ¨ ording and Falcke 100 101 ince disruption (yr) NGC 5905 TDE2 D3-13 z) flux for TDE2 MBH ∼ 5 × 107 M⊙ D3-13, MBH ∼ 2 × 107 M⊙ (Gezari 10−1 100 101 102 Flux density (mJy) 10−9 10−8 10−7 10−6 10−5 10−4 10−3 10−2 10−1 100 101 Snapshot Rate (deg−2) B07 B07, 2 month FIRST-NVSS ATATS MOST BS11 Scott96 deVries04 LOFAR VAST-Deep SKAMP 10 GHz, always radio-loud (a) 1.4 GHz, always radio-loud (a) 200 MHz, always radio-loud (a) 1.4 GHz, loud for ˙ M < 2% (b) 1.4 GHz, burst (c) 5 GHz, Giannios & Metzger (2011) Figure 3. The snapshot rate of TDE jets. We show 2-σ upper- limits from: Scott (1996) and Bower et al. (2007, B07) at 5 GHz,
et al. 100 101 4.9 GHz (m p = 0.38) 6.7 GHz (m p = 0.72) 15 GHz (m p = 0.07) 25 GHz (m p < 0.03) 0.3−10 keV (!30) a Flux density (mJy) 101 101 44 GHz 90 GHz 200 GHz 225 GHz 345 GHz b Flux density (mJy) Time since March 25 UT (d) Figure 3. Radio light curves of Swift J164449.3+573451 at 5 − 345 GHz re VLSS 2x2 deg
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