Magnetars: SGRs and AXPs Magnetic field distribution 1805.01680 (taken from Olausen, Kaspi 2014) Fields from P-Pdot using magneto-dipole formula Magnetars in the Galaxy ◼ ~25 SGRs and AXPs, plus 6 candidates, plus radio pulsars with high magnetic fields (about them see arXiv: 1010.4592)… ◼ Young objects (about 103-5 year). (see a review in arXiv:1503.06313 and the catalogue description in 1309.4167) Catalogue: http://www.physics.mcgill.ca/~pulsar/magnetar/main.html 1703.00068 Spatial distribution Scale height ~20 pc The first parallax for magnetar XTE J1810−197 was measured due to radio observations, 2008.06438. 1907.13267 Birth rate of magnetars Recent modeling favours somehow larger values: 1903.06718. However, the result is model dependent. In particular, it depends on the model of field decay. Fraction of magnetars among NSs is uncertain. Typically, the value ~10% is quoted (e.g. 0910.2190). This is supported observationally and theoretically. Historical notes ◼ 05 March 1979. The ”Konus” experiment & Co. Venera-11,12 (Mazets et al., Vedrenne et al.) ◼ Events in the LMC. SGR 0520-66. ◼ Fluence: about 10-3 erg/cm2 Mazets et al. 1979 N49 – supernova remnant in the Large Magellanic cloud (e.g. G. Vedrenne et al. 1979) Magnetar on pension? 2003.11730 The source is not active since 1979. Just in 2020 it was for the first time detected at E>10 keV in quiescence. Main types of activity of SGRs ◼ Weak bursts. L<1042 erg/s ◼ Intermediate. L~1042–1043 erg/s ◼ Giant. L<1045 erg/s ◼ Hyperflares. L>1046 erg/s See the review in Rea, Esposito 1101.4472 Power distribution is similar to the distribution of earthquakes in magnitude Normal bursts of SGRs and AXPs ◼ Typical weak bursts of SGR 1806-29, SGR 1900+14 and of AXP 1E 2259+586 detected by RXTE (from Woods, Thompson 2004) Outbursts Individual flares often appear during period of activity. They are called outbursts. SGR J1935+2154 is the most recurring transient during last years. 127 bursts in 2-3 years. This amount allows detailed statistical studies. 2003.10582 See the review in Rea, Esposito 1101.4472 Intermediate SGR bursts Examples of intermediate bursts. The forth (bottom right) is sometimes defined as a giant burst (for example by Mazets et al.). (from Woods, Thompson 2004) Giant flare of the SGR 1900+14 (27 August 1998) ◼ Ulysses observations (figure from Hurley et al.) ◼ Initial spike 0.35 s ◼ P=5.16 s ◼ L>3 1044 erg/s ◼ ETOTAL>1044 erg Hurley et al. 1999 Hyperflare of SGR 1806-20 ◼ 27 December 2004 A giant flare from SGR 1806-20 was detected by many satellites: Swift, RHESSI, KonusWind, Coronas-F, Integral, HEND, … ◼ 100 times brighter than any other! Palmer et al. astro-ph/0503030 Integral RHESSI C O R O N A S - F 27 Dec 2004: Giant flare of the SGR 1806-20 ◼ Spike 0.2 s ◼ Fluence 1 erg/cm2 ◼ E(spike)=3.5 1046 erg ◼ L(spike)=1.8 1047 erg/s ◼ Long «tail» (400 s) ◼ P=7.65 s ◼ E(tail) 1.6 1044 erg ◼ Distance 15 kpc – see the latest data in arXiv: 1103.0006 Konus observations Mazets et al. 2005 The myth about Medusa SGR 1806-20 - I SGR 1806-20 displayed a gradual increase in the level of activity during 2003-2004 (Woods et al 2004; Mereghetti et al 2005) ▪ enhanced burst rate ▪ increased persistent luminosity The 2004 December 27 EventSpring 2003 Spring 2004 Autumn 2003 Autumn 2004 Bursts / day (IPN) 20-60 keV flux (INTEGRAL IBIS) Mereghetti et al 2005 SGR 1806-20 - II ◼ Four XMM-Newton observations before the burst (the last one on October 5 2004, Mereghetti et al 2005) ◼ Pulsations clearly detected in all observations ◼ Ṗ ~ 5.5x10-10 s/s, higher than the “historical” value ◼ Blackbody component in addition to an absorbed power law (kT ~ 0.79 keV) ◼ Harder spectra: Γ ~ 1.5 vs. Γ ~ 2 ◼ The 2-10 keV luminosity almost doubled (LX ~ 1036 erg/s) Growing twist (images from Mereghetti arXiv: 0804.0250) Anomalous X-ray pulsars Identified as a separate group in 1995. (Mereghetti, Stella 1995 Van Paradijs et al.1995) • Similar periods (5-10 sec) • Constant spin down • Absence of optical companions • Relatively weak luminosity • Constant luminosity Anomalous X-ray Pulsars: main properties ◼ About fourteen sources known: 1E 1048.1-5937, 1E 2259+586, 4U 0142+614, 1 RXS J170849-4009, 1E 1841-045, 3XMM J185246.6+003317, CXOU 010043-721134, AX J1845-0258, CXOU J164710-455216, XTE J1810-197, 1E 1547.0-5408, PSR J1622-4950, CXOU J171405.7-381031 ◼ Persistent X-ray emitters, L ≈ 1034 -1035 erg/s ◼ Pulsations with P ≈ 2 -10 s (0.33 sec for PSR 1846) ◼ Large spindown rates, Ṗ/P ≈ 10-11 s-1 ◼ No evidence for a binary companion, association with a SNR in several cases Known AXPs CXO 010043-7211 8.0 4U 0142+61 8.7 1E 1048.1-5937 6.4 1E 1547.0-5408 2.1 CXOU J164710-4552 10.6 1RXS J170849-40 11.0 XTE J1810-197 5.5 1E 1841-045 11.8 AX J1845-0258 7.0 PSR J1622-4950 4.3 CXOU J171405.7-381031 3.8 1E 2259+586 7.0 Sources Periods, s http://www.physics.mcgill.ca/~pulsar/magnetar/main.html Are SGRs and AXPs brothers? ◼ Bursts of AXPs (more than half burst) ◼ Spectral properties ◼ Quiescent periods of SGRs (0525-66 since 1983) Gavriil et al. 2002 Bursts of the AXP 1E1547.0-5408 0903.1974 Bursts of the AXP 1E1547.0-5408 0903.1974 Some bursts have pulsating tails with spin period. Unique AXP bursts? (Woods et al. 2005 astro-ph/ astro-ph/0505039) Bursts from AXP J1810-197. Note a long exponential tail with pulsations. R < ctrise ≈ 300 km: a compact object Pulsed X-ray emission: a neutron star A Tale of Two Populations ? SGRs: bursting X/γ-ray sources Single class of objects AXPs: peculiar class of steady X-ray sources A Magnetar Pulse profiles of SGRs and AXPs Hard X-ray Emission Mereghetti et al 2006 INTEGRAL revealed substantial emission in the 20 -100 keV band from SGRs and APXs Hard power law tails with Г ≈ 1-3 (see 1712.09643 about spectral modeling) Hard emission pulse SGRs and AXPs SGRs and AXPs soft X-ray Spectra ◼ 0.5 – 10 keV emission is well represented by a blackbody plus a power law SGR 1806-20 (Mereghetti et al 2005) AXP 1048-5937 (Lyutikov & Gavriil 2005) See also discussions in: arXiv: 1001.3847, 1009.2810 SGRs and AXPs soft X-ray Spectra ◼ kTBB ~ 0.5 keV, does not change much in different sources ◼ Photon index Г ≈ 1 – 4, AXPs tend to be softer ◼ SGRs and AXPs persistent emission is variable (months/years) ◼ Variability is mostly associated with the non-thermal component ◼ About polarization see 2001.07663 Magnetar spectra in comparison 1503.06313 1903.05648 Hard tails can be due to upscattering of thermal photons from the surface in the magnetosphere, see e.g. 2012.10815. Magnetars can behave like radio pulsars 1908.04304 XTE J1810−197 Was the first magnetar to show PSR-like radio emission. Activity in radio is transient. Shows short bursts which resemble FRBs (but are much weaker). Young and fast magnetar with radio Swift J1818.0–1607 Discovered in March 2020. Spin period 1.36 s. Characteristic age 240 yrs. Radio pulses. Weak quiescent emission. 2004.04083 About first radio detection of this source see http://www.astronomerstelegram.org/?read=13577 Suppression of radio during bursts 1710.03718 PSR J1119−6127 The rotationally powered radio emission shuts off coincident with the occurrence of multiple X-ray bursts. Galactic center magnetar SGR/PSR J1745−2900 1802.07884 1307.6331 Radio pulsations detection in 2013 The largest dispersion measure and rotation measure among PSRs. <1 pc from Sgr A* Evolution of the Galactic center magnetar after the outburst in 2013 2003.07235 Low-field magnetars See a review in arXiv:1303.6052 SGR 0418+5729 and Swift J1822.3–160 The first low-field magnetar 1303.5579 Only after ~3 years of observations it was possible to detect spin-down. The dipolar field is ~6 1012 G. The dipolar field could decay, and activity is due to the toroidal field. SGR 0418+5729 Large field (at last) ... But multipoles! 1308.4987 XMM-Newton observations allowed to detect a spectral line which is variable with phase. If the line is interpreted as a proton cyclotron line, then the field in the absorbing region is 2 1014 – 1015 G SGR 0418+5729 1308.4987 a. Spectrum for the phases 0.15-0.17 and the best-fit model (red) for the phase averaged spectrum b. Residuals for this model c. Residuals for the model with a line d. Residuals for the BB+powel law model (no line) Magnetars and supernovae KASEN & BILDSTEN (2010) With large field and short spin a newborn NS can contribute a lot to the luminosity of a SN. Parameters needed About young millisecond magnetars see also 1906.02610, and a review in 2103.10878. Magnetars and GRBs 1804.08652 Papers to read • Woods, Thompson astro-ph/0406133 – old classical review • Mereghetti arXiv: 0804.0250 • Rea, Esposito arXiv: 1101.4472 - outbursts • Turolla, Esposito arXiv: 1303.6052 - Low-field magnetars • Mereghetti et al. arXiv: 1503.06313 • Turolla, Zane, Watts arXiv: 1507.02924 – Big general review • Beloborodov, Kaspi arXiv: 1703.00068 • Esposito et al. arXiv: 1803.05716 • Coti Zelati et al. arXiv: 1710.04671 – outbursts • Gourgouliatos, Esposito 1805.01680 – magnetic fields • Dall’Osso, Stella 2103.10878 - millisecond magnetars