The first detection of a pulsar with ALMA

Abstract

Pulsars are neutron stars, stellar corpses left over after supernova explosions of stars about ten times as massive as our Sun, with densities comparable to the atomic nucleus', spinning with periods from few milliseconds up to few seconds, and endowed with magnetic fields thousands billion times stronger than the Earth's, where particles are accelerated to the relativistic regime producing electromagnetic radiation across the entire spectrum. Although there is a general consensus on the fact that pulsars' radio emission is coherent in nature, whereas the emission from the optical to high-energy $\gamma$-rays is due to incoherent processes, it has not been established yet at which wavelengths the transition occurs, a key information for all emission models of pulsar magnetospheres. Of course, to address this issue covering the spectral region between high-frequency radio waves and the mid-IR is crucial. We used the Atacama Large Millimetre Array (ALMA) to observe the Vela pulsar (PSR\, B0833$-$45), one of the very few observed in radio and from the mid-infrared up to the very high-energy $\gamma$-rays. We detected Vela at frequencies of 97.5, 145, 233, 343.5 GHz and found that its energy density spectrum follows a power-law of spectral index $\alpha =-0.93\pm 0.16$. The ALMA spectrum corresponds to very high brightness temperatures - from $10^{17}$ to $10^{15}$ K - suggesting that a coherent radiative process still contributes to the mm/sub-mm emission. This is, therefore, the first indication of coherent emission other than radio originating in pulsars. At the same time, we identified an extended structure, preliminarily detected in ground-based observations. We support its interpretation as a counter-jet protruding from the pulsar.

13 pages, 6 figures, published in ApJ Letter

References in corpus (6)

• The ATNF Pulsar Catalogue
• Spectral properties of 441 radio pulsars
• Phase resolved spectroscopy of the Vela pulsar with XMM-Newton
• Fermi-LAT Detection of Pulsed Gamma-rays Above 50 GeV from the Vela Pulsar
• The Vela Pulsar With an Active Fallback Disk
• The effect of an offset polar cap dipolar magnetic field on the modeling of the Vela pulsar's $\gamma$-ray light curves

Cited by in corpus (13)

• Multi-TeV Emission From the Vela Pulsar
• pulsar_spectra: A pulsar flux density catalogue and spectrum fitting repository
• Submillimeter pulsations from the magnetar XTE J1810-197
• The first ultraviolet detection of the Large Magellanic Cloud pulsar PSR B0540-69 and its multi-wavelength properties
• Detection of pulses from the Vela pulsar at millimeter wavelengths with phased ALMA
• Spectral analysis of 22 radio pulsars using SKA-Low precursor stations
• The Vela pulsar and its pulsar wind nebula Vela-X using 13 years of Fermi-LAT Observations
• ALMA discovery of Punctum -- a highly polarized mm source in nuclear starburst galaxy NGC 4945
• Modelling energy-dependent pulsar light curves
• Retuning radio astronomy for axion dark matter with neutron stars
• Rotationally-driven VHE emission from the Vela pulsar
• 50-250 MHz Pulsar Census with an SKA-Low prototype station: Spectra and Polarization
• Modelling energy-dependent pulsar light curves due to curvature radiation