The optical and near-infrared spectrum of the Crab pulsar with X-shooter

Abstract

Pulsars are well studied all over the electromagnetic spectrum, and the Crab pulsar may be the most studied object in the sky. Nevertheless, a high-quality optical to near-infrared spectrum of the Crab or any other pulsar has not been published to date. Obtaining a properly flux-calibrated spectrum enables us to measure the spectral index of the pulsar emission, without many of the caveats from previous studies. This was the main aim of this project, but we could also detect absorption and emission features from the pulsar and nebula over an unprecedentedly wide wavelength range. A spectrum was obtained with the X-shooter spectrograph on the Very Large Telescope. Particular care was given to the flux-calibration of these data. A high signal-to-noise spectrum of the Crab pulsar was obtained from 300 to 2400nm. The spectral index fitted to this spectrum is flat with alpha_nu=0.16 +- 0.07. For the emission lines we measure a maximum velocity of 1600 km/s, whereas the absorption lines from the material between us and the pulsar is unresolved at the 50 km/s resolution. A number of Diffuse Interstellar Bands and a few near-IR emission lines that have previously not been reported from the Crab are highlighted.

arXiv commentThis is the version resubmitted to A&A with replies to th first referee report

References in corpus (34)

• emcee: The MCMC Hammer
• Astrophysics Source Code Library
• X-shooter, the new wide band intermediate resolution spectrograph at the ESO Very Large Telescope
• WISeREP - An Interactive Supernova Data Repository
• Molecfit: A general tool for telluric absorption correction. I. Method and application to ESO instruments
• An Analysis of the Shapes of Interstellar Extinction Curves. V. The IR-Through-UV Curve Morphology
• An atmospheric radiation model for Cerro Paranal. I. The optical spectral range
• The surprising Crab pulsar and its nebula: A review
• The Crab pulsar in the 0.75-30 MeV range as seen by CGRO COMPTEL
• An advanced scattered moonlight model for Cerro Paranal
• Observations of the Crab Nebula and its pulsar in the far-ultraviolet and in the optical
• The dust and gas content of the Crab Nebula
• Flux calibration of medium-resolution spectra from 300 nm to 2500 nm: Model reference spectra and telluric correction
• Diffuse Interstellar Bands in NGC 1448
• The X-shooter GRB afterglow legacy sample (XS-GRB)
• Phosphorus in the Young Supernova Remnant Cassiopeia A
• The Importance of Physical Models for Deriving Dust Masses and Grain Size Distributions in Supernova Ejecta I: Radiatively Heated Dust in the Crab Nebula
• The young pulsar PSR B0540-69.3 and its synchrotron nebula in the optical and X-rays
• Phase-resolved Crab Studies with a Cryogenic TES Spectrophotometer
• Spectroscopy of High Energy BL Lac Objects with X-shooter on the VLT
• Optical and infrared observations of the Crab Pulsar and its nearby knot
• The Crab pulsar and its red knot in the near-infrared
• Characterization of the Inner Knot of the Crab: The Site of the Gamma-ray Flares?
• The near-infrared detection of PSR B0540-69 and its nebula
• The optical to gamma-ray emission of the Crab pulsar: a multicomponent model
• Near-Infrared, Kilosecond Variability of the Wisps and Jet in the Crab Pulsar Wind Nebula
• The Optical Spectrum of the Vela Pulsar
• Synchrotron Model for the Infrared, Optical and X-Ray Emission of the Crab Pulsar
• The Nature of the H2-Emitting Gas in the Crab Nebula
• H2 Temperatures in the Crab Nebula
• Observational and theoretical constraints for an H$\alpha$-halo around the Crab Nebula
• Optical Spectrum of Main-, Inter- and Off-pulse Emission from Crab Pulsar
• Optical spectroscopy of the radio pulsar PSR B0656+14
• The location of the Crab pulsar emission region: Restrictions on synchrotron emission models

Cited by in corpus (5)

• Very-High-Energy Emission From Pulsars
• Thermal and nonthermal emission in the optical-UV spectrum of PSR B0950+08
• Utilizing cosmic-ray positron and electron observations to probe the averaged properties of Milky Way pulsars
• Spatial Variations and Breaks in the Optical-NIR spectra of the Pulsar and PWN in SNR 0540-69.3
• Possible counterpart signal of the Fermi bubbles at the cosmic-ray positrons