Artikel zu "PSR J1811-1925 in G11.2-0.3" (I) (II) Bow shock / Wind nebulae Table
X-ray Pulsar XTE J1810-197 & PSR J1811-1925 PSR J1811-1736, PSR in a highly eccentric binary system K1 Chandra associates pulsar and historic supernova K2 The Pulsar Wind Nebula in G11.2-0.3 K3 Phase Coherent Timing of PSR J1811–1925 K4.1 Correlated radio and X-ray Structures in PWNe K4.2 Parsec-Scale Tails	— :    IV magnetar Current NS — SNR census: The Evidence (Vorl) Neutron star supernova remnant census (IV_SNRs) K5 PSR J1811-1925 and its PWN (INTEGRAL) Literatur

PSR J1811-1925 in G11.2-0.3

K1  Chandra associates pulsar and historic supernova

PSR J1811-1925 in G11.2-0.3 PSR J1811-1925;   (in G11.2-0.3 dist: ~ 5 kpc)   P = 64.7 ms;  P' = 4.2×10-14 s s-1;    tc = P/2P' = 24 kyr;    B = 1.8·1012 G   E'rot = 6.4·1039 erg s-1

PSR J1811-1925 — G11.2-0.3
	Authors: Kaspi, V. M., Roberts, M. E., Vasisht, G., Gotthelf, E. V., Pivovaroff, M., & Kawai, N.
	Journal-ref: ApJ 560 (2001) 371 [astro-ph/0107292 ]
	Title: Chandra Observations of G11.2-0.3: Implications for Pulsar Ages
Abstract: We present Chandra X-ray Observatory imaging observations of the young Galactic supernova remnant G11.2-0.3. The image shows that the previously known young 65-ms X-ray pulsar is at position (J2000) RA 18h 11m 29.22s, DEC -19o 25'27.''6, with 1 sigma error radius 0.''6. This is within 8'' of the geometric center of the shell. This provides strong confirming evidence that the system is younger, by a factor of ~12, than the characteristic age of the pulsar. The age discrepancy suggests that pulsar characteristic ages can be poor age estimators for young pulsars. Assuming conventional spin down with constant magnetic field and braking index, the most likely explanation for the age discrepancy in G11.2-0.3 is that the pulsar was born with a spin period of ~62 ms. The Chandra image also reveals, for the first time, the morphology of the pulsar wind nebula. The elongated hard-X-ray structure can be interpreted as either a jet or a Crab-like torus seen edge on. This adds to the growing list of highly aspherical pulsar wind nebulae and argues that such structures are common around young pulsars.

[January 11, 2001] — Scientists using NASA's Chandra X-ray Observatory have found new evidence that a pulsar in the constellation of Sagittarius was created when a massive star exploded, witnessed by Chinese astronomers in the year 386 AD. If confirmed, this will be only the second pulsar to be clearly associated with a historic event.

Chandra / Roberts Fig. — Comparison of X-ray PWN emission and radio emission: red represents photons of energies 0.6--1.65~keV, green is 3.5~cm radio, and blue is 4-9 keV photons.

"Determining the true ages of astronomical objects is notoriously difficult, and for this reason, historical records of supernovae are of great importance," said Kaspi. In roughly the past 2,000 years, fewer than 10 reports of probable supernovae have been archived mostly by Asian astronomers. Of those handful, the remnant of 1054 AD, the Crab Nebula, was until now the only pulsar whose birth could be associated with a historic event and, hence, the only neutron star that has a firm age.

Between mid-April and mid-May in the year 386 AD, a young "guest star," presumably a supernova, was recorded by Chinese observers in the direction of the sky now known as the constellation of Sagittarius. In the 1970s, radio astronomers discovered an expanding nebula of gas and high-energy particles, called G11.2-0.3, that is believed to be the remnant of that explosion. In 1997, a team of X-ray astronomers used Japan’s ASCA satellite to discover a pulsar in the same area of the sky. Past attempts to identify the pulsar with G11.2-0.3, and hence the ancient Chinese observations, have been controversial.

The location of the pulsar at the center of the remnant provides new evidence that it is associated with the remnant. Since pulsars are known to move rapidly away from where they are formed, a pulsar near the center of the remnant implies the system must be very young, since not enough time has elapsed for the pulsar to travel far from its birthplace.

"We believe that the pulsar and the supernova remnant G11.2-0.3 are both likely to be left over from the explosion seen by the Chinese observers over 1600 years ago," said Roberts. "While this is exciting by itself, it also raises new questions about what we know about pulsars especially during their infancies."

These questions follow from a discrepancy that arose when the ASCA team applied the present spin rate to current models to determine the pulsar's estimated lifetime and compare it to the age of G11.2-0.3. The result was an age of roughly 24,000 years — far predating the birth year of 386 AD.

To explain this contradiction, the Chandra team argues that this pulsar may have had approximately the same spin rate today as it did at its birth, as had been suggested by the ASCA data. If this is true, then it could have important implications for the conventional wisdom regarding pulsars, which, may be born spinning more slowly than has been thought.

"We now have strong evidence that the standard age estimate for this pulsar is probably wrong, and it is much younger than previously believed," said Kaspi. "This, in turn, suggests that other standard pulsar age estimates may be wrong as well, and this has important implications for the population as a whole."

In addition to these results, the Chandra observations of G11.2-0.3 have, for the first time, revealed the bizarre appearance of the pulsar wind nebula (also known as "plerions") at the center of the supernova remnant. Its rough cigar-like shape is in contrast to the graceful arcs observed around the Crab and Vela pulsars. However, together with those pulsars, G11.2-0.3 demonstrates that such complicated structures are ubiquitous around young pulsars. This has left astronomers confounded.

Chandra observed G11.2-0.3 with the Advanced CCD Imaging Spectrograph at two epochs: August 6, 2000, and October 15, 2000, for approximately 20,000 and 15,000 seconds respectively.

— E' = 6.4·1039 erg s-1
	Authors: Roberts, M.S.E., Tam, C.R., Kaspi, V.M., Maxim Lyutikov, Gautam Vasisht, Michael Pivovaroff, E.V. Gotthelf, Nobuyuki Kawai
	Journal-ref: ApJ 588 (2003) 992 [astro-ph/0206450 ]
	Title: The Pulsar Wind Nebula in G11.2-0.3
Image credit: Chandra / VLA / Roberts Fig. — G11.2-0.3: A Textbook Supernova Abstract: We present an X-ray and radio study of the wind nebula surrounding the central pulsar PSR J1811-1925 in the supernova remnant G11.2-0.3. Using high resolution data obtained with the Chandra X-ray observatory and with the VLA radio telescope we show the X-ray and radio emission is asymmetric around the pulsar, despite the latter's central position in the very circular shell. The new X-ray data allow us to separate the synchrotron emission of the pulsar wind nebula from the surrounding thermal emission and that from the pulsar itself. Based on X-ray data from two epochs, we observe temporal variation of the location of X-ray hot spots near the pulsar, indicating relativistic motion. We compare thermal emission observed within the shell, which may be associated with the forward shock of the pulsar wind nebula, to thermal emission from a nearby portion of the remnant shell, the temperature of which implies an expansion velocity consistent with the identification of the remnant with the historical event of 386 A.D. The measured X-ray and radio spectral indices of the nebula synchrotron emission are found to be consistent with a single synchrotron cooling break. The magnetic field implied by the break frequency is anomalously large given the apparent size and age of the nebula if a spherical morphology is assumed, but is consistent with a bipolar morphology.    In Chandra's X-ray image, the pulsar and a cigar-shaped cloud of energetic particles, known as a pulsar wind nebula, are predominantly seen as high-energy X-rays (blue). A shell of heated gas from the outer layers of the exploded star surrounds the pulsar and the pulsar wind nebula and emits lower-energy X-rays (represented in green and red).

[2002] Pulsar J1811-1925 and supernova in the year 386 AD
G11.2-0.3 is a remarkably spherical young SNR plausibly associated with the historical event of 386 A.D. recorded by Chinese astrologers.

Chandra / Roberts Fig. — ACIS observing epochs 1 (top) and 2 (bottom), smoothed with a 3'' Gaussian, and 3.5 cm (bottom) VLA X-band image with a 3.1'' × 2.8'' restoring beam. The line in the images shows the 1-D slice for the profiles shown in Figure 5.

Literatur

Tam, C., Roberts, M. S. E., & Kaspi, V. M. 2002, ApJ, 572, 202 (Paper II)
Kaspi, V. M. & Helfand, D. J. 2002, To appear in “Neutron Stars in Supernova Remnants” (ASP Conference Proceedings), eds P. O. Slane and B. M. Gaensler

Cusumano et al., A&A, 375 (2001) 397–404

—
	Authors: F.P. Gavriil, V.M. Kaspi, M.S.E. Roberts
	Ref: 34th Cospar Scientific Assembly 6 Jan 2003 [astro-ph/0301090 ]
	Title: Phase Coherent Timing of PSR J1811-1925: The Pulsar at the Heart of G11.2-0.3
Abstract: The X-ray Pulsar PSR J1811-1925 in the historic supernova remnant G11.2-0.3 has a characteristic age over 10 times the age of the remnant. This likely implies that its current spin period, 65 ms, is close to its birth spin period. Alternatively, the pulsar may have an unusually high braking index. We report here on regular Rossi X-ray Timing Explorer/ Proportional Counting Array (RXTE/PCA) timing observations of the pulsar that were designed to measure its braking index. We provide a preliminary phase-coherent timing solution which includes a significant n''. The braking index we measure is >> 3, likely a result of conventional timing noise. We also report on a preliminary analysis of the pulsar's unusually hard spectrum: we determine a photon index of G = 1.78 ± 0.74$, for the pulsed component of the spectra, consistent within the uncertainties with previous ASCA and Chandra observations. The pulsed emission of PSR J1811-1925 is seen beyond 30 keV, and the pulsations remain sinusoidal up to and beyond this energy.

Crab nebula - PWN - Pulsar Wind Nebulae
	Authors: Mallory S.E. Roberts, Maxim Lyutikov, Bryan M. Gaensler, Crystal Brogan, Cindy R. Tam, Roger W. Romani
	ref: "X-Ray and Radio Connections" (2004) [astro-ph/0406592 ]
	Title: Ain't No Crab, PWN Got A Brand New Bag: Correlated radio and X-ray Structures in Pulsar Wind Nebulae
Abstract: The traditional view of radio pulsar wind nebulae (PWN), encouraged by the Crab nebula's X-ray and radio morphologies, is that they are a result of the integrated history of their pulsars' wind. The radio emission should therefore be largely unaffected by recent pulsar activity, and hence minimally correlated with structures in the X-ray nebulae. Observations of several PWN, both stationary (sPWN) and rapidly moving (rPWN), now show clear morphological relationships between structures in the radio and X-ray with radio intensity variations on the order of unity. We present high-resolution X-ray and radio images of several PWN of both types and discuss the morphological relationships between the two wavebands.

—
	Authors: Bryan M. Gaensler
	Ref: IAU Symposium, Vol. 218, (2004) [astro-ph/0405290 ]
	Title: Shocks and Wind Bubbles Around Energetic Pulsars
Abstract: The Crab Nebula demonstrates that neutron stars can interact with their environments in spectacular fashion, their relativistic winds generating nebulae observable across the electromagnetic spectrum. At many previous conferences, astronomers have discussed, debated and puzzled over the complicated structures seen in the Crab, but have been limited to treating most other pulsar wind nebulae (PWNe) as simple calorimeters for a pulsar's spin-down energy. However, with the wealth of high-quality data which have now become available, this situation has changed dramatically. I here review some of the main observational themes which have emerged from these new measurements. Highlights include the ubiquity of pulsar termination shocks, the unambiguous presence of relativistic jets in PWNe, complicated time variability seen in PWN structures, and the use of bow shocks to probe the interaction of pulsar winds with the ambient medium. Figure 1. Image credit: Chandra / ATCA / AAO / Gaensler Examples of the three broad phases in PWN evolution. (a) Chandra X-ray image of the Crab Nebula; (b) ATCA radio image of SNR B0453–685 in the LMC; (c) AAO Ha (greyscale) and Chandra X-ray (contours) images of the bow shock powered by PSR B1957+20.

K4.2   PSR J1509-5850 and PSR J1740+1000 — Parsec-Scale Tails

PSR J1509-5850 — d = 4 kpc — P = 89 ms — NH = 2.1 × 1022 cm-2 — LX(0.5-8 keV) ~ 1 × 1033 erg s-1 PSR J1740+1000 — d = 1.4 kpc — P = 154 ms — NH = 1 × 1022 cm-2 — LX(0.5-8 keV) ~ 2 × 1033 erg s-1
	Authors: O. Kargaltsev, Z. Misanovic, G. G. Pavlov, J. A. Wong, G. P. Garmire
	Journal-ref: (2008) [0802.2963 ]
	Title: X-ray Observations of Parsec-Scale Tails behind Two Middle-Aged Pulsars
Fig. 14.— Composite X-ray (red) and radio (blue) image of the field of the J1509 tail. Image credit: Kargaltsev et al. (2008) Fig. 16.— X-ray luminosities of PWNe versus pulsar spin-down power (see KP08). The data points corresponding to pulsars with firmly established long X-ray tails are shown in color (as well as the names of the pulsars). The blue and red points correspond to the total PWN luminosities and the luminosities of the compact bright features associated with the PWN “heads”, respectively. In most cases the luminosity of the extended tail component substantially exceeds that of the head. Abstract: Chandra and XMM-Newton resolved extremely long tails behind two middle-aged pulsars, J1509-5850 and J1740+1000. The tail of PSR J1509-5850 is discernible up to 5.6' from the pulsar (6.5 pc at a distance of 4 kpc), with a flux of fX(0.5-8 keV) = 2 × 10-13 erg cm-2 s-1. The tail spectrum fits an absorbed power-law (PL) model with the photon index of G = 2.3 ± 0.2, corresponding to the luminosity of LX(0.5-8 keV) ~ 1 × 1033 erg s-1, for NH = 2.1 × 1022 cm-2. The tail of PSR J1740+1000 is firmly detected up to 5' (2 pc at a 1.4 kpc distance), with a flux of fX(0.4-10 keV) = 4.2 × 10-12 erg cm-2 s-1. The PL fit yields photon index of G = 1.45 ± 0.05 and NH = 1 × 1021 cm-2. The large extent of the tails suggests that the bulk flow in the tails starts as mildly relativistic downstream of the termination shock, and then gradually decelerates. Within the observed extent of the J1509-5850 tail, the average flow speed exceeds 5,000 km s-1, and the equipartition magnetic field is a few times 10-5 G. For the J1740+1000 tail, the equipartition field is a factor of a few lower. The harder spectrum of the J1740+1000 tail implies either less efficient cooling or a harder spectrum of injected electrons. For the high-latitude PSR J1740+1000, the orientation of the tail on the sky shows that the pulsar is moving toward the Galactic plane, which means that it was born from a halo-star progenitor. The comparison between the J1509 and J1740 tails and the X-ray tails of other pulsars shows that the X-ray radiation efficiency correlates poorly with the pulsar spin-down luminosity or age. The X-ray efficiencies of the ram-pressure confined pulsar wind nebulae (PWNe) are systematically higher than those of PWNe around slowly moving pulsars with similar spin-down parameters.    Thanks to the high sensitivity and angular resolution of the Chandra and XMM-Newton observatories, about 50 PWNe have been detected in X-rays (Kaspi et al. 2006; Gaensler & Slane 2006; Kargaltsev & Pavlov 2008, hereafter KP08). The X-ray observations have shown that PWNe have complex morphologies, including toroidal structures around the pulsar, jets along the pulsar’s spin axis, and cometary tails (see KP08 for Chandra images). The well-known example of such a bowshock-tail PWN is “the Mouse PWN” produced by the young, energetic pulsar J1747-2958 (tc = 26 kyr, E'rot = 2.5 × 1036 erg s-1), which shows an X-ray tail of the projected length lortogonal ~ 1 pc (Gaensler et al. 2004). In addition to the Mouse, about a dozen X-ray PWNe with bowshock-tail morphologies have been discovered recently (KP08). Interestingly, one of the longest tails, lortogonal ~ 1.5 pc, was found behind the 3 Myr old pulsar B1929+10, with a relatively low spin-down power, E'rot = 3.8 × 1033 erg s-1 (Wang et al. 1993; Becker et al. 2006; Misanovic et al. 2007). Although most of the known PWNe are powered by much younger and more powerful pulsars, it has been noticed (Kargaltsev et al. 2007) that bowshock PWNe with extended tails are generally brighter than PWNe around slowly moving pulsars. PSR J1509–5850 (hereafter J1509) was discovered in the Parkes Multibeam Pulsar Survey (Kramer et al. 2003). The pulsar is located in the Galactic plane at the dispersion measure (DM) distance of about 4 kpc. To study the X-ray properties of the pulsar and look for its PWN, we observed this field with Chandra. In addition to detecting the pulsar, the observation revealed a spectacular long tail, first reported by Kargaltsev et al. (2006). It was briefly described by Hui & Becker (2007; hereafter HB07), who also reported the discovery of diffuse radio emission, possibly associated with the tail. References Becker, W., et al. 2006, ApJ, 645, 1421 Gaensler, B.M., & Slane, P.O. 2006, ARA&A 44, 17 Hui, C.Y., Becker, W. 2007, A&A, 470, 965 [0704.1265 ] Radio and X-ray nebulae associated with PSR J1509-5850 (HB07) Kargaltsev, O., & Pavlov, G. G. 2008, in 40 Years of Pulsars (KP08) Kargaltsev, O., Pavlov, G.G., Sanwal, D., Wong, J., & Garmire, G.P. 2006, BAAS 38, 359 Kaspi, V.M., Roberts, M.S.E., & Harding, A.K. 2006, CUP Kramer, M., et al. 2003, MNRAS 342, 1299 Misanovic, Z., Pavlov, G. G., & Garmire, G. P. 2007, ApJ, Wang, Q.D., Li, Z.-Y., & Begelman, M.C. 1993, Nature 364, 127 The X-ray-emitting trail of the nearby pulsar PSR1929 + 10

K5  PSR J1811-1925 and its PWN (INTEGRAL)

PSR J1811-1925 — d ~ 5 kpc —
	Authors: A.J. Dean, A. De Rosa, V.A. McBride, R. Landi, A.B. Hill, L. Bassani, A. Bazzano, A.J. Bird, P. Ubertini
	Journal-ref: MNRAS 384 (2008) L29 [0711.0648 ]
	Title: INTEGRAL observations of PSR J1811-1925 and its associated Pulsar Wind Nebula
Abstract: We present spectral measurements made in the soft (20-100 keV) gamma-ray band of the region containing the composite supernova remnant G11.2-0.3 and its associated pulsar PSR J1811-1925. Analysis of INTEGRAL/IBIS data allows characterisation of the system above 10 keV. The IBIS spectrum is best fitted by a power law having photon index of G = 1.8 ± 0.3 and a flux of fX(20-100 keV) = 1.5 × 10-11 erg cm-2 s-1. Analysis of archival Chandra data over different energy bands rules out the supernova shell as the site of the soft gamma-ray emission while broad band (1-200 keV) spectral analysis strongly indicates that the INTEGRAL/IBIS photons originate in the central zone of the system which contains both the pulsar and its nebula. The composite X-ray and soft gamma-ray spectrum indicates that the pulsar provides around half of the emission seen in the soft gamma-ray domain; its spectrum is hard with no sign of a cut off up to at least 80 keV. The other half of the emission above 10 keV comes from the PWN; with a power law slope of 1.7 its spectrum is softer than that of the pulsar. From the IBIS/ISGRI mosaics we are able to derive 2 sigma upper limits for the flux from the location of the nearby TeV source HESS J1809-193 to be fX(20-100 keV) = 4.8 × 10-12 erg cm-2 s-1. Image credit: INTEGRAL / A.J. Dean et al Fig. 1.— INTEGRAL IBIS/ISGRI 18–60 keV image of the region around PSR J1811-1925. Note that the image structure around the position of PSR J1809-1917 is well below the detection threshold as determined by Bird et al. (2007) for the 3rd IBIS/ISGRI catalogue. The fit ellipse (Aharonian et al. 2007) of the extended HESS source is reported with a magenta ellipse. In the inset we show the Chandra images (~ 5' × 5') in 0.2–2 keV (left) and 4–8 keV (right). We have also examined the likelihood of an association between PSR J1811-1925 and HESS J1809-193. Although PSR J1811-1925 is the most energetic pulsar in the region, the only one detected above 10 keV and thus a possible source of energy to fuel the TeV fluxes, there is no morphological evidence to support this pairing, making it an unlikely counterpart.  2 PSR J1811-1925  An interesting case to investigate is the 65ms pulsar PSR J1811-1925, discovered in X-rays by ASCA in the supernova remnant (SNR) G11.2-0.3 (Torii et al. 1997). It is a composite SNR showing both an extended shell component and a compact plerionic component. This discovery strongly suggests a direct association of the pulsar with the SNR and with a “guest star” witnessed by Chinese astronomers in A.D. 386 as proposed by Clark & Stephenson (1977). The distance of the system is ~ 5 kpc as inferred from H I measurements. Thanks to X-ray observations performed by Chandra (Kaspi et al. 2001) it was possible to localise the pulsar to within a few arc seconds from the geometric centre of the shell of the SNR (Tam & Roberts 2003), thus providing an indication that the system may be young. The system PSR J1811-1925/G11.2-0.3 is located near the TeV source HESS J1809-193, recently discovered by the HESS telescope array (Aharonian et al. 2007). Although the pulsar is energetic enough to power the high energy gamma-rays, the association with the TeV source is not likely since the pulsar is clearly the companion of G11.2-0.3 and HESS J1809-193 is offset from the supernova remnant, implying that PSR J1811-1925 could not have produced the TeV source due to its motion. The likelihood of an association is further questioned by the presence of a second pulsar/PWN system, J1809-1917 (Kargaltsev & Pavlov 2007), which is closer to the centroid of the HESS source and also capable of supplying sufficient energy from the pulsar to power HESS J1809-193. References Aharonian, F., Akhperjanian, A.G., Bazar-Bachi, A.R. et al, 2007, A&A Kargaltsev, O. & Pavlov, G.G., 2007, Kaspi, V.M., Roberts, M.E., Vasisht, et al., 2001, ApJ 560, 371 Roberts, M.S.E., Tam, C.R., Kaspi, V.M. et al., 2003, ApJ 588, 992 Tam, C. & Roberts, M.S.E., 2003, ApJ 598, 30 Torii, K., Tsunemi, H., Dotani, T., & Mitsuda, K. 1997, ApJ 489, 145 (PSR J1811-1925) Torii, K., et al. 1998, ApJ 494, L207 (PSR J1617-5055 in RCW 103)

Literatur zu ""
Kaspi, V.M., Roberts, M.E., Vasisht, G., Gotthelf, E.V., Pivovaroff, M., & Kawai, N.	2001	ApJ 560, 371	"Chandra Observations of G11.2-0.3: Implications for Pulsar Ages"
Roberts, M.S.E., Tam, C.R., Kaspi, V.M., et al.	2003	ApJ 588, 992	"The Pulsar Wind Nebula in G11.2-0.3"
Dean, A. J.; de Rosa, A.; McBride, V. A.; et al.	2008	MNRAS 384, L29	"INTEGRAL observations of PSR J1811-1925 and its associated Pulsar Wind Nebula"

H. Heintzmann

( Eintrag vom 17.4.2008)

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