New X-ray observations of the Geminga pulsar wind nebula

Abstract

Previous observations of the middle-aged pulsar Geminga with XMM-Newton and Chandra have shown an unusual pulsar wind nebula (PWN), with a 20" long central (axial) tail directed opposite to the pulsar's proper motion and two 2' long, bent lateral (outer) tails. Here we report on a deeper (78 ks) Chandra observation and a few additional XMM-Newton observations of the Geminga PWN. The new Chandra observation has shown that the axial tail, which includes up to three brighter blobs, extends at least 50" (i.e., 0.06 d_{250} pc) from the pulsar. It also allowed us to image the patchy outer tails and the emission in the immediate vicinity of the pulsar with high resolution. The PWN luminosity, L_{0.3-8 keV} ~ 3\times 10^{29} d_{250}^2 erg/s, is lower than the pulsar's magnetospheric luminosity by a factor of 10. The spectra of the PWN elements are rather hard (photon index ~ 1). Comparing the two Chandra images, we found evidence of PWN variability, including possible motion of the blobs along the axial tail. The X-ray PWN is the synchrotron radiation from relativistic particles of the pulsar wind; its morphology is connected with the supersonic motion of Geminga. We speculate that the outer tails are either (1) a sky projection of the limb-brightened boundary of a shell formed in the region of contact discontinuity, where the wind bulk flow is decelerated by shear instability, or (2) polar outflows from the pulsar bent by the ram pressure from the ISM. In the former case, the axial tail may be a jet emanating along the pulsar's spin axis, perhaps aligned with the direction of motion. In the latter case, the axial tail may be the shocked pulsar wind collimated by the ram pressure.

16 pages, including 6 figures; minor changes in the text; typos corrected; published in ApJ

References in corpus (26)

• The USNO-B Catalog
• The Evolution and Structure of Pulsar Wind Nebulae
• The Second-Generation Guide Star Catalog: Description and Properties
• Discovery of Spatial and Spectral Structure in the X-Ray Emission from the Crab Nebula
• Pulsar Wind Nebulae in the Chandra Era
• The Variable Jet of the Vela Pulsar
• On the polar caps of the 3 Musketeers
• The Mouse That Soared: High Resolution X-ray Imaging of the Pulsar-Powered Bow Shock G359.23-0.82
• Constraining Pulsar Magnetosphere Geometry with Gamma-Ray Light Curves
• Relativistic MHD simulations of pulsar bow-shock nebulae
• A Chandra Search for Coronal X Rays from the Cool White Dwarf GD 356
• Birth Kick Distributions and the Spin-Kick Correlation of Young Pulsars
• Pulsar bow-shock nebulae. II. Hydrodynamical simulation
• Ultraviolet, X-ray, and Optical Radiation from the Geminga Pulsar
• X-ray Observations of Parsec-Scale Tails behind Two Middle-Aged Pulsars
• Three-dimensional hydrodynamic simulations of asymmetric pulsar wind bow shocks
• Optical photometry of the PSR B0656+14 and its neighborhood
• X-ray emission from PSR B1800-21, its wind nebula, and similar systems
• Chandra observations of the pulsar PSR B1929+10 and its environment
• The pulsar wind nebula of the Geminga pulsar
• Vela, its X-ray nebula, and the polarization of pulsar radiation
• Winds, B-Fields, and Magnetotails of Pulsars
• Blazing trails: Microquasars as head-tail sources and the seeding of magnetized plasma into the ISM
• Probing the Pulsar Wind Nebula of PSR B0355+54
• On the complex X-ray structure tracing the motion of Geminga
• The neutral gas in the environs of the Geminga gamma-ray pulsar

Cited by in corpus (29)

• Evidence for vacuum birefringence from the first optical polarimetry measurement of the isolated neutron star RX\, J1856.5$-$3754
• Using HAWC to Discover Invisible Pulsars
• Geminga's puzzling pulsar wind nebula
• Fermi-LAT Search for Pulsar Wind Nebulae around gamma-ray Pulsars
• Gamma-ray Pulsar Revolution
• Pulsar Wind Nebulae Created by Fast-Moving Pulsars
• Pulsar-wind nebulae and magnetar outflows: observations at radio, X-ray, and gamma-ray wavelengths
• Cosmic-Ray Propagation in Light of Recent Observation of Geminga
• A rapid cosmic-ray increase in BC 3372-3371 from ancient buried tree rings in China
• A broadband X-ray study of the Geminga pulsar with NuSTAR and XMM-Newton
• Chandra Observations of Outflows from PSR J1509-5850
• Extended Emission from the PSR B1259-63/SS 2883 Binary Detected with Chandra
• Simultaneous X-ray and radio observations of the radio-mode switching pulsar PSR B1822-09
• The Young Pulsar J1357-6429 and Its Pulsar Wind Nebula
• Deep Chandra Observations of the Pulsar Wind Nebula Created by PSR B0355+54
• Full-3D relativistic MHD simulations of bow shock pulsar wind nebulae: emission and polarization
• Detection of extended gamma-ray emission around the Geminga pulsar with H.E.S.S
• The Vela and Geminga pulsars in the mid-infrared
• Chandra observations of the elusive pulsar wind nebula around PSR B0656+14
• First Detection of a Pulsar Bow Shock Nebula in Far-UV: PSR J0437-4715
• A Chandra search for the pulsar wind nebula around PSR B1055-52
• The Identification of the X-ray Counterpart to PSR J2021+4026
• Gamma-ray halos around pulsars: impact on pulsar wind physics and galactic cosmic ray transport
• High energy gamma-ray emission from compact galactic sources in the context of observations with the next generation Cherenkov Telescope Arrays
• Interpretation of the puzzling gamma-ray spectrum of the Geminga halo
• Detection of continuum radio emission associated with Geminga
• Rapid X-ray variations of the Geminga pulsar wind nebula
• Spatially resolved polarization variation of the Crab Nebula
• Method for testing diffusive shock acceleration and diffusion propagation of 1-100 TeV cosmic electrons with multiwavelength observations of the Geminga halo and pulsar wind nebula