GLOBAL SPECTRAL ENERGY DISTRIBUTION OF THE CRAB NEBULA IN THE PROSPECT OF THEPLANCKSATELLITE POLARIZATION CALIBRATION

Abstract The Crab nebula is a prominent pulsar wind nebula detected in multiband observations ranging from radio to very high-energy γ-rays. Recently, γ-rays with energies above 1 PeV have been detected by the Large High Altitude Air Shower Observatory, and the energy of the most energetic particles in the nebula can be constrained. In this paper, we investigate the broadest spectral energy distribution of the Crab nebula and the energy distribution of the electrons emitting the multiwavelength nonthermal emission based on a one-zone time-dependent model. The nebula is powered by the pulsar, and high-energy electrons/positrons with a broken power-law spectrum are continually injected in the nebula as the pulsar spins down. Multiwavelength nonthermal emission is generated by the leptons through synchrotron radiation and inverse Compton scattering. Using appropriate parameters, the detected fluxes for the nebula can be well reproduced, especially for the γ-rays from 102 MeV to 1 PeV. The results show that the detected γ-rays can be produced by the leptons via the inverse Compton scattering, and the lower limit of the Lorentz factor of the most energetic leptons is ∼ 8.5 × 109. It can be concluded that there exist electrons/positrons with energies higher than 4.3 PeV in the Crab nebula.

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NIKA 150 GHz polarization observations of the Crab nebula and its spectral energy distribution

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731551 ◽

2018 ◽

Vol 616 ◽

pp. A35 ◽

Cited By ~ 10

Author(s):

A. Ritacco ◽

J. F. Macías-Pérez ◽

N. Ponthieu ◽

R. Adam ◽

P. Ade ◽

...

Keyword(s):

Energy Distribution ◽

Spectral Index ◽

Crab Nebula ◽

Spectral Energy Distribution ◽

Polarization Degree ◽

Kinetic Inductance Detectors ◽

Spectral Energy ◽

Kinetic Inductance ◽

Wide Range ◽

The Crab Nebula

The Crab nebula is a supernova remnant exhibiting a highly polarized synchrotron radiation at radio and millimetre wavelengths. It is the brightest source in the microwave sky with an extension of 7 by 5 arcmin, and is commonly used as a standard candle for any experiment which aims to measure the polarization of the sky. Though its spectral energy distribution has been well characterized in total intensity, polarization data are still lacking at millimetre wavelengths. We report in this paper high resolution observations (18′′ FWHM) of the Crab nebula in total intensity and linear polarization at 150 GHz with the NIKA camera. NIKA, operated at the IRAM 30 m telescope from 2012 to 2015, is a camera made of Lumped Element Kinetic Inductance Detectors (LEKIDs) observing the sky at 150 and 260 GHz. From these observations we are able to reconstruct the spatial distribution of the polarization degree and angle of the Crab nebula, which is found to be compatible with previous observations at lower and higher frequencies. Averaging across the source and using other existing data sets we find that the Crab nebula polarization angle is consistent with being constant over a wide range of frequencies with a value of − 87.7° ± 0.3 in Galactic coordinates. We also present the first estimation of the Crab nebula spectral energy distribution polarized flux in a wide frequency range: 30–353 GHz. Assuming a single power law emission model we find that the polarization spectral index βpol = – 0.347 ± 0.026 is compatible with the intensity spectral index β = – 0.323 ± 0.001.

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The Crab nebula variability at short time-scales with the Cherenkov telescope array

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3599 ◽

2020 ◽

Vol 501 (1) ◽

pp. 337-346

Author(s):

E Mestre ◽

E de Oña Wilhelmi ◽

D Khangulyan ◽

R Zanin ◽

F Acero ◽

...

Keyword(s):

Gamma Ray ◽

Crab Nebula ◽

Spectral Energy Distribution ◽

Spectral Energy ◽

Telescope Array ◽

Cherenkov Telescopes ◽

Cherenkov Telescope ◽

Emission Models ◽

Short Time ◽

The Crab Nebula

ABSTRACT Since 2009, several rapid and bright flares have been observed at high energies (>100 MeV) from the direction of the Crab nebula. Several hypotheses have been put forward to explain this phenomenon, but the origin is still unclear. The detection of counterparts at higher energies with the next generation of Cherenkov telescopes will be determinant to constrain the underlying emission mechanisms. We aim at studying the capability of the Cherenkov Telescope Array (CTA) to explore the physics behind the flares, by performing simulations of the Crab nebula spectral energy distribution, both in flaring and steady state, for different parameters related to the physical conditions in the nebula. In particular, we explore the data recorded by Fermi during two particular flares that occurred in 2011 and 2013. The expected GeV and TeV gamma-ray emission is derived using different radiation models. The resulting emission is convoluted with the CTA response and tested for detection, obtaining an exclusion region for the space of parameters that rule the different flare emission models. Our simulations show different scenarios that may be favourable for achieving the detection of the flares in Crab with CTA, in different regimes of energy. In particular, we find that observations with low sub-100 GeV energy threshold telescopes could provide the most model-constraining results.

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An intermittent extreme BL Lac: MWL study of 1ES 2344+514 in an enhanced state

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1702 ◽

2020 ◽

Vol 496 (3) ◽

pp. 3912-3928

Author(s):

MAGIC Collaboration: V A Acciari ◽

S Ansoldi ◽

L A Antonelli ◽

A Arbet Engels ◽

A Babić ◽

...

Keyword(s):

Crab Nebula ◽

Spectral Energy Distribution ◽

Broad Band ◽

High Energy ◽

Spectral Energy ◽

Bl Lac ◽

Very High Energy ◽

Γ Ray ◽

Using Data ◽

The Crab Nebula

ABSTRACT Extreme high-frequency BL Lacs (EHBL) feature their synchrotron peak of the broad-band spectral energy distribution (SED) at νs ≥ 1017 Hz. The BL Lac object 1ES 2344+514 was included in the EHBL family because of its impressive shift of the synchrotron peak in 1996. During the following years, the source appeared to be in a low state without showing any extreme behaviours. In 2016 August, 1ES 2344+514 was detected with the ground-based γ-ray telescope FACT during a high γ-ray state, triggering multiwavelength (MWL) observations. We studied the MWL light curves of 1ES 2344+514 during the 2016 flaring state, using data from radio to very-high-energy (VHE) γ-rays taken with OVRO, KAIT, KVA, NOT, some telescopes of the GASP-WEBT collaboration at the Teide, Crimean, and St. Petersburg observatories, Swift-UVOT, Swift-XRT, Fermi-LAT, FACT, and MAGIC. With simultaneous observations of the flare, we built the broad-band SED and studied it in the framework of a leptonic and a hadronic model. The VHE γ-ray observations show a flux level of 55 per cent of the Crab Nebula flux above 300 GeV, similar to the historical maximum of 1995. The combination of MAGIC and Fermi-LAT spectra provides an unprecedented characterization of the inverse-Compton peak for this object during a flaring episode. The Γ index of the intrinsic spectrum in the VHE γ-ray band is 2.04 ± 0.12stat ± 0.15sys. We find the source in an extreme state with a shift of the position of the synchrotron peak to frequencies above or equal to 1018 Hz.

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VHE SPECTRAL ENERGY DISTRIBUTION OF CRAB NEBULA COMPARED WITH THE PREDICTION OF A SYNCHROTRON SELF-COMPTON EMISSION MODEL

Cosmic Rays for Particle and Astroparticle Physics ◽

10.1142/9789814329033_0001 ◽

2011 ◽

Author(s):

V.G. SINITSYNA ◽

A.Y. ALAVERDIAN ◽

A.S. BOLDYREV ◽

S.S. BORISOV ◽

R.M. MIRSAFATIKHOV ◽

...

Keyword(s):

Energy Distribution ◽

Crab Nebula ◽

Spectral Energy Distribution ◽

Spectral Energy ◽

Emission Model

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MAGIC very large zenith angle observations of the Crab Nebula up to 100 TeV

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936899 ◽

2020 ◽

Vol 635 ◽

pp. A158 ◽

Cited By ~ 1

Author(s):

◽

V. A. Acciari ◽

S. Ansoldi ◽

L. A. Antonelli ◽

A. Arbet Engels ◽

...

Keyword(s):

Zenith Angle ◽

Crab Nebula ◽

Spectral Energy Distribution ◽

Spectral Energy ◽

Atmospheric Transmission ◽

Cherenkov Telescopes ◽

Large Zenith Angle ◽

Energy Domain ◽

Emission Models ◽

The Crab Nebula

Aims. We measure the Crab Nebula γ-ray spectral energy distribution in the ~100 TeV energy domain and test the validity of existing leptonic emission models at these high energies. Methods. We used the novel very large zenith angle observations with the MAGIC telescope system to increase the collection area above 10 TeV. We also developed an auxiliary procedure of monitoring atmospheric transmission in order to assure proper calibration of the accumulated data. This employs recording optical images of the stellar field next to the source position, which provides a better than 10% accuracy for the transmission measurements. Results. We demonstrate that MAGIC very large zenith angle observations yield a collection area larger than a square kilometer. In only ~ 56 h of observations, we detect the γ-ray emission from the Crab Nebula up to 100 TeV, thus providing the highest energy measurement of this source to date with Imaging Atmospheric Cherenkov Telescopes. Comparing accumulated and archival MAGIC and Fermi/LAT data with some of the existing emission models, we find that none of them provides an accurate description of the 1 GeV to 100 TeV γ-ray signal.

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Modelling the Spectral Energy Distribution of Star-Forming Galaxies with Radiative Transfer Methods

Star-Formation Rates of Galaxies ◽

10.1017/9781316875445.012 ◽

2021 ◽

pp. 204-224

Author(s):

Cristina Popescu

Keyword(s):

Radiative Transfer ◽

Energy Distribution ◽

Spectral Energy Distribution ◽

Spectral Energy ◽

Star Forming

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Influence of Microlensing on Spectral Anomalies of the Lensed Objects

Open Astronomy ◽

10.1515/astro-2017-0324 ◽

2011 ◽

Vol 20 (3) ◽

Author(s):

S. Simić ◽

L. Č. Popović ◽

P. Jovanović

Keyword(s):

Energy Distribution ◽

Spectral Energy Distribution ◽

Angular Size ◽

Black Body ◽

Spectral Energy

AbstractHere we consider the influence of microlensing on the spectrum of a lensed object with the angular size 5 μas accepting that the composite emission of this object originates from three different regions arranged around its center. We assume that the lensed object has three concentric regions with a black-body emission; the temperatures of these regions are 10 000 K, 7500 K and 5000 K. We investigate how the integral spectral energy distribution (SED) of such stratified source changes due to microlensing by a group of solarmass stars. We find that the SED and flux ratios in the photometric B, V and R passbands show considerable changes during a microlens event. This indicates that the flux anomaly observed in some lensed quasars may be caused by microlensing of a stratified object.

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