Radio Emissions of Magnetars Observations at Nanshan Xinjiang

Radio Emissions of Magnetars & Observations at Nanshan Xinjiang Astronomical Observatory Yuan Jianping, Wang Na, Liu Zhiyong Outline Introduction of magnetar Radio emissions of Magnetars Observations of Magnetars at Nanshan

Anomalous X-ray Pulsar and Soft Gamma Repeaters X-ray pulsators p: 2 -12 s Period derivative： 10 -13 ~10 -10 s s-1 Lx >> Edot Strong B: 1014 ~1015 G > Bcrit No evidence for companion. Magnetic energy powered Magnetar model (Thompson & Duncom )

Some Major Unsolved Problems Wood, Thompson 2006 What is the birth rate of AXP and SGRs What fractions of NS go through a phase of strong B activity Why are the periods clustered in an interval of 2 -12 s Are SGRs and AXPs fundamentally NS What is the initial spin period of magnetars What is the evolutionary sequence of magnetar Do the magnetars and high B-field radio pulsars form a continuum of magnetic activity

AXP SGR • AXP (9+3) • SGR (7+2) • Spin period (2 - 12 s) • Spin period (2 -12 s) • Period derivative： 10 -10 ~ 1013 s s-1 • Period derivative： 10 -13 ~10 -10 • Characteristic age: 103 ~105 yr • No companion • X-ray luminosity: 1034 ~1035 erg s-1> spin-down luminosity • X-ray and soft gamma-ray emission. • No companion, some associate with SNR • 3 sources have Giant flares, 1044 erg s-1 (Mereghetti 2000)

Emission Mechanisms • Persistent emission: it can be induced by twisting of the external B caused by the motions of the star interior (mereghetti 2008) • Bursts and flares: are explained in terms of magnetic reconnections (Lyubarsky 2002), fast-mode breakdown model (Heyl & Hernquist 2005) • See Tong Hao’s talk.

• radio quite? • Their radio detection started ~ 10 years ago.

SGR 1900+14 • A fading radio source within the X-ray box of it. (Frail 1999) • A short-lived cloud of ionized gas, powered by relativistic particles ejected at the time of intense burst of HE photons.

SGR 1806− 20 • Giant gamma ray flare on 27 Dec 2004 • Radio emission Jan 2005, was suggested arises from the debris ejected during the explosion Cameron et al. Nat. 2005

2 in 9 SGRs are detected to emit radio emission Flux density: 100 u. Jy – 500 m. Jy, Flux density decreased Visible in several months

XTE J 1810− 197 • Transient X-ray outburst began 2003. P: 5. 54 s (Ibrahim et al 2004) • Radio emission (Halpern et al 2005), P: 5. 54 s （Camilo et al 2006)， Camilo et al 2006

Camilo et al 2007

• Flux density decreased significantly Lazaridis et al 2009

Lazaridis et al 2008 Lazaridis et al 2007 S ~ν− 0. 5 (Camilo et al 2007 )

AXP 1 E 1547− 5408 (PSR J 1550− 5418) Radio signals P = 2 s (Camilo et al 2007) DM = 830 pc cm-3 Camilo et al 2007

Single pulses profiles The average profile Camilo et al 2007

Polarization Camilo et al 2007 The radiation is highly linearly polarized, Especially at high frequency, it is almost 100 per cent linearly polarized.

• Flux density is variable • Spectrum is different Camilo et al 2008

1 E 2259+586 (See Malov’s talk) Radio emission from two AXPs are reported by Malofeev Mean duration of 120± 20 ms, 1. 7% DM: 79± 4 pc/cm− 3 Flux density < 150 m. Jy at 87 MHz (Malofeev 2005), 35± 25 m. Jy at 111 MHz (Malofeev 2007), Estimated spectral index (S ~ν−α ) α> 2. 5 Estimated : S 1500 < 0. 05 m. Jy

4 U 0142+61 (See Malov’s talk) X-ray pulsar with a P of 8. 7 s (Israel 1994) DM 27(5) pc cm− 3 S 111, 30(20)m. Jy (Malofeev 2010) Large flux-density fluctuation were observed. Spectral index >2. 7, steep spectrum.

PSR J 1622− 4950 Discovered in HTRU survey, with a P of 4. 326 s & DM 820 pc cm 3 A greatly varying flux density, ~ 6 with 24 h Profile changes shape on short timescales. Pdot is fluctuating within a factor of 2,

PSR J 1622− 4950 A very high B ~ 2. 8× 1014 G, the highest B of any radio pulsar known to date. Appears to have an inverted spectrum similar to two AXPs a magnetar, the first to be discovered via its radio emission The x-ray counterpart be in quiescence Highlights unprecedented features of the emission of the magnetars across radio band.

Totally, 5 in 12 AXPs are reported to emit radio emission. The discoveries provided an exciting new spectral window on magnetar physics Another link between magnetar and radio pulsar. Average pulse profile change significant Spectrum are different from radio pulsar. Flux density is variable Mechanism appears to have a different origin or perhaps multiple origins, compared to the normal radio pulsars.

• The radio emission isn't stable, repeated observations are warranted • Is radio emission related to X−ray behavior? • Do they have narrow radio emissions?

Observations at Nanshan • • Nanshan 25 m radio telescope Central frequency 1540 MHz BW: 320 MHz, 125 channels Single pulse mode 1 bit sample every 1 ms July, 2009 – Dec, 2010 3600 s (1 h)

Single Pulse Search • De-dispersed at a set of trial DM ranging from 0 to 1000 pc cm-3, spacing is 1 pc cm-3 • Flux density limit ~ 4. 8 Jy α = 5 (S/N threshold) β = sqrt(π/2) ( one-bit digitization) k: Boltzmann’ constant Trec, Tspl, Tsky are noise np = 2 number of polarization τ = 1 ms, sampling interval Δf = 320 MHz, BW A = 490. 87 m 2 the area of antenna ESAMDIN et al 2008

PSR B 0525+21 DM=50. 94

http: //www. physics. mcgill. ca/~pulsar/magnetar/main. html Name P d. P / dt e− 11 Activity 4 U 0142+61 8. 6883297 0. 196 H X O I, B XTE 1810− 197 5. 539 0. 81 H X R, B, transient 1 E 2259+586 6. 9789 0. 048 H X O, B H = soft gamma rays/hard X-rays (>10 ke. V); X = X-rays (1 -10 ke. V); O = optical/near-infrared; I = mid to far infrared; R = radio, B = burst, F = Giant flare

Single Pulse Search • 4 U 0142+61 3*1 hr, negative • XTE J 1810− 197 5*1 hr, negative • 1 E 2259+586 2*1 hr, negative

Folding 4 U 0142+61 DM 27(5) pc cm− 3 1 E 2259+586 DM 79(4) pc cm− 3 XTE J 1810− 197 DM 178 pc cm− 3 Dedispersed with reported DM and folded with catalog period. Negative. For XTE J 1810− 197 1. Flux density decreased. 2. It would be detectable when it is in activity

Sumarry Nondetection of single pulses with S 1540>~4. 8 Jy Nondetection of 1 -hr integrated pulses with S 1540> ~ 0. 26 m. Jy Magnetar seems do not emit strong pulse sporadically in RRAT’s way. We are looking forward the large telescope in Xinjiang!