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The First Fast Burst Observed Both in Radio And INTEGRAL discovery of a magnetar burst with associated radio emission. The first fast burst observed both in radio and hard X-ray comes from the magnetar SGR 1935+2154. Submitted to ApJ Letters https://arxiv.org/abs/2005.06335 Sandro Mereghetti, Volodymyr Savchenko, Carlo Ferrigno et al., INAF, Universit´ede Gen`eve. June 8, 2020 – Ecogia Science Meetings 2019–2020 INTEGRAL discovery of a magnetar burst with associated radio emission. Preamble Table of Contents Introduction Magnetars Fast radio bursts SGR 1935+2154 The discovery ID of a \normal" magnetar The 2020 outburst. The STARE2 radio detection The CHIME radio detection The INTEGRAL detection Distance Estimate Some relevant facts Comparisons with other FRB and magnetar flares Implication for models of FRBs June 8, 2020 – Ecogia Science Meetings 2019–2020 1 INTEGRAL discovery of a magnetar burst with associated radio emission. Introduction Magnetars • Isolated neutron stars powered by magnetic energy (24+5 sources). • Slowly rotating (P ∼ 1 − 10 s) and fast spin-down P_ ∼ 10−10{10−11 s/s 34 36 _ • LX ≈ 10 {10 erg/s >> Erot • Many transients with 32 LQuiesc ≈ 10 erg/s • show rarely (5 cases) some transient pulsed radio emission, associated to X-ray outbutsts but very bright, with large pulse-to-pulse variability, with pulse morphologies that change enormously in minutes • Reviews from Kaspi & Beloborodov (From the Handbook of Pulsar Astronomy, by (2017) and Mereghetti et al. (2015). Lorimer and Kramer) June 8, 2020 – Ecogia Science Meetings 2019–2020 2 INTEGRAL discovery of a magnetar burst with associated radio emission. Introduction: Magnetars Magnetar locations From the McGill online catalog (Olausen & Kaspi, 2014), http: // www. physics. mcgill. ca/ ˜ pulsar/ magnetar/ main. html • located in the Galactic plane or Magellanic Clouds • associated with young stellar clusters and supernova remnants (8+2) June 8, 2020 – Ecogia Science Meetings 2019–2020 3 INTEGRAL discovery of a magnetar burst with associated radio emission. Introduction: Magnetars Magnetar persistent spectra The combined Swift/Nustar spectrum of 1E 2259 Comparison of spectra from X-per, Geminga, and the (from Kaspi & Beloborodov 2017) magnetically-powered AXP 4U 0142+61 (from Mereghetti et al. 2015) Thermal spectrum kT ∼ 0.5 keV with hard tails up to 200 keV June 8, 2020 – Ecogia Science Meetings 2019–2020 4 INTEGRAL discovery of a magnetar burst with associated radio emission. Introduction: Magnetars SGR and AXMPs are magnetars • Soft Gamma Repeaters (SGR) were discovered in 1979. Initially confused with GRB, it was realised they originate from Galactic objects with • Anomalous X-ray pulsars softer spectra (AXP) were discovered in 80s and 90s characterized by soft • Neutron-star origin of SGR 0526−66 spectra, higher-than-usual was clear from pulsation at 8 s luminosity, and several seconds • The model of spontaneous magnetic long periods field decay was proposed in the 90s to • In 2002, SGR-like bursting explain both bursts (crustal quakes or activity was discovered from reconnections) and persistent emission. an AXP, confirming the link • Magnetic field exceeding 1014 G was required and it was confirmed by high spin-down in several sources. The distinguishing feature is the bursting activity with burst duration less than seconds. June 8, 2020 – Ecogia Science Meetings 2019–2020 5 INTEGRAL discovery of a magnetar burst with associated radio emission. Introduction: Magnetars Magnetar flaring - Short bursts (∆t . 1 s) Examples of single bursts (from Kaspi & Beloborodov 2017) 39 41 • LX ∼ 10 − 10 erg/s • Hard X-ray/Soft γ-ray thermal spectra with kT ∼ 30 − 40 keV June 8, 2020 – Ecogia Science Meetings 2019–2020 6 INTEGRAL discovery of a magnetar burst with associated radio emission. Introduction: Magnetars Magnetar flaring- Intermediate bursts (∆t = 1 − 40 s) Burst forest from SGR 1900−14 (from Israel et al. 2008). • Emission of a forest of bursts 41 43 • At peak LX ∼ 10 − 10 erg/s • abrupt onset • Hard X-ray/Soft γ-ray thermal spectra June 8, 2020 – Ecogia Science Meetings 2019–2020 7 INTEGRAL discovery of a magnetar burst with associated radio emission. Introduction: Magnetars 44 Magnetar flaring - Giant bursts (LX & 3 × 10 erg/s) The giant burst of SGR 1806−20 seen with SPI-ACS (the peak at 2 × 106 counts is not shown) (from Mereghetti et al. 2005) • Only three observed 1979 March 5 SGR 0626−66, 1998 Aug 27 SGR 1900+14, 2004 Dec 27 SGR 1806−20 • initial spike with hard spectrum, thermal tail with energy 1044 erg and pulsation from the magnetar • Stringent upper limit on radio emission (Tendulkar et al., 2016). June 8, 2020 – Ecogia Science Meetings 2019–2020 8 INTEGRAL discovery of a magnetar burst with associated radio emission. Introduction: Magnetars Outburst activity models Internal source of heat External source of heat • Local magnetic stresses deform • Crustal displacements twist up the part of the stellar crust. external B-field. • Plastic flows convert the magnetic • Returning currents hit and heat energy into heat. the NS surface. • Energy is partly is conducted up • The bundle dissipates as the to the surface and radiated energy supply from the star (thermal afterglow) interior decreases. Probably both mechanisms are at work to sustain emission for years. June 8, 2020 – Ecogia Science Meetings 2019–2020 9 INTEGRAL discovery of a magnetar burst with associated radio emission. Introduction: Fast radio bursts • Fast radio bursts (FRBs) are millisecond-duration pulses that originate from as-yet-unidentified extragalactic sources. • First one discovered in 2007 • Similar to pulses from Galactic radio pulsars, but the flux density is 1010 times larger • More than 100 sources • Multiple bursts have been detected from ∼20 FRB sources and only a few have secure localizations (first by Areceibo FRB 121102, then by CHIME) • two semi-periodic (several days) FRB sources • FRB 121102, the first to be localized, is in a star-forming region in a dwarf galaxy with a luminosity distance of about 1 Gpc. • astoundingly large all-sky rate 3 4 −1 −1 ΓFRB(> 1, Jyms) ∼ 10 − 10 sky day above a 1 Jy ms fluence threshold → 103 Gpc−3yr−1 The first radio burst with dispersion measure 375 pc cm−3(Cordes & Chatterjee, 2019) • One catalog is at http://frbcat.org/ and review by Cordes & Chatterjee (2019). June 8, 2020 – Ecogia Science Meetings 2019–2020 10 INTEGRAL discovery of a magnetar burst with associated radio emission. SGR 1935+2154: The discovery SGR 1935+2154 • Discovered in 2014 owing to a 0.5-s burst observed by Swift (Israel et al., 2016) • P = 3.24 s. P_ = 1.4 × 10−11 • B = 2.2 × 1014 Gauss • Spin-down age: τ = 3600 years 34 • Lspin−down = 2 × 10 erg/s • The source spectrum is well modelled by a blackbody with kT = 0.5 keV plus a power-law component with Γ = 2 • Likely associated to SNR G57.2+0.8 (Kothes et al., 2018) • estimated distances of the SNR ∼12.5 Chandra plus XMM–Newton kpc (Kothes et al., 2018), 4.5{9 kpc background-subtracted pulse profiles of SGR 1935+2154 (Israel et al., 2016). (Ranasinghe et al., 2018), and 6.6±0.7 (Zhou et al., 2020). June 8, 2020 – Ecogia Science Meetings 2019–2020 11 INTEGRAL discovery of a magnetar burst with associated radio emission. SGR 1935+2154: ID of a \normal" magnetar Bursting story of SGR 1935+2154 • Hundreds of bursts and one intermediate flare in 2016 (Kozlova et al., 2016; Lin et al., 2020a) • Four outbursts observed before • The burst most prolific magnetar. 2020 From (Younes et al., 2017). Duration of bursts and fluence for burst forest in 2020 (Lin et al., 2020a). June 8, 2020 – Ecogia Science Meetings 2019–2020 12 INTEGRAL discovery of a magnetar burst with associated radio emission. SGR 1935+2154: The 2020 outburst. Swift-INTEGRAL-eRosita persistent emission Evolution of the SGR 1935+2154 mean flux measured in soft X-rays with Swift/XRT (red points) and SRG/eROSITA (blue point) and upper limits from INTEGRAL in hard X-rays (black points). The horizontal dashed line shows the persistent flux level in the 0.5-4 keV energy band, calculated with parameters from Younes et al. (2017). June 8, 2020 – Ecogia Science Meetings 2019–2020 13 INTEGRAL discovery of a magnetar burst with associated radio emission. SGR 1935+2154: The 2020 outburst. The first FRB{magnetar burst coincidence On 28 April 2020, a soft/X-ray burst is observed in timing coincidence with a FRB, both coming from the direction of SGR 1935+2154. Burst from Apr. 28 14:34:24 T 0 SGR 1935+2154 IBAS Alert sent, 0.5 s- long burst of ∼100 14:34:29 T +5 s GCN Not. 8611 0 Crab, associated to SGR 1935+2154 CHIME radio 400- 20:45 T +6 hr Atel 13681 0 800 MHz Apr. 29 03:04 T0 + 12.5 hr STARE 2 radio 1.4 GHz Atel 13684 INTEGRAL (first to re- 09:30:38 T +19 hr GCN Circ 27668 0 port association) 10:53 INTEGRAL Atel 13685 AGILE (no imaging, 3σ 11:05 Atel 13686 association) Konus-WIND (no imag- 15:34:34 T +1 d GCN Circ 27669 0 ing) 19:05 Insight-XHMT Atel 13687 Konus-WIND (no imag- 19:42 Atel 13688 ing) June 8, 2020 – Ecogia Science Meetings 2019–2020 14 INTEGRAL discovery of a magnetar burst with associated radio emission. SGR 1935+2154: The STARE2 radio detection STARE2 Detection plots The FRB FLARE2 localisation (Bochenek et al., 2020). The de-dispersed FRB seen by FLARE2 (Bochenek et al., 2020). June 8, 2020 – Ecogia Science Meetings 2019–2020 15 INTEGRAL discovery of a magnetar burst with associated radio emission. SGR 1935+2154: The STARE2 radio detection STARE2 burst facts • STARE2 is an array of 3 radio telescopes operating at 1.4 GHz in USA.
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