HESS J1427−608: AN UNUSUAL HARD, UNBROKEN Γ-Ray SPECTRUM IN a VERY WIDE ENERGY RANGE

Guo, Xiaolei; Xin, Y.; Liao, Neng-Hui; Yuan, Qiang; Gao, Wei-Hong; He, H. H.; Fan, Yi‐Zhong; Liu, Siming

doi:10.3847/1538-4357/835/1/42

Cited by 9 publications

(11 citation statements)

References 43 publications

(63 reference statements)

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“…No associated X-ray point source with similar column density was reported using XMM-Newton data (Fujinaga et al 2013). Above 3 GeV, a Fermi-LAT point source was detected at the center of HESS J1427−608 with a hard spectral index Γ GeV = 1.87 ± 0.17 and an integrated flux of Φ GeV = (3.06 ± 0.73) × 10 −10 photon cm −2 s −1 (Guo et al 2017). Figure 1 (left) shows the HGPS significance map with the associated X-ray and GeV sources overlaid.…”

Section: Application On Hess J1427−608 and Hess J1458−608supporting

confidence: 58%

“…Figure 2 (left) shows the corresponding spectral energy distributions (SEDs) reported in the Fermi-LAT catalogs. The spectrum of the point source detected above 3 GeV (Guo et al 2017) smoothly connects to the H.E.S.S. measurements while the 4FGL catalog reports a source with a pulsar-like spectrum represented by a logarithmic parabola.…”

Section: Multiwavelength Constraintsmentioning

confidence: 53%

“…Three Fermi-LAT sources are located inside the R spec of HESS J1427−608 (3FHL J1427.9−6054, 4FGL J1427.8−6051 and the source detected by Guo et al 2017, as illustrated in Fig. 1, left).…”

Section: Multiwavelength Constraintsmentioning

confidence: 99%

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Multiwavelength constraints on the unidentified Galactic TeV sources HESS J1427−608, HESS J1458−608, and new VHE γ-ray source candidates

Devin

Renaud

Lemoine‐Goumard

et al. 2021

A&A

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Aims. Among the γ-ray sources discovered at high and very-high energies, a large fraction still lack a clear identification. In particular, the H.E.S.S. Galactic Plane Survey (HGPS) revealed 78 TeV sources among which 47 are not clearly associated with a known object. Multiwavelength data can help identify the origin of the very-high energy γ-ray emission, although some bright TeV sources have been detected without clear counterparts. We present a multiwavelength approach to constrain the origin of the emission from unidentified HGPS sources. Methods. We present a generic pipeline that explores a large database of multiwavelength archival data toward any region in the Galactic plane. Along with a visual inspection of the retrieved multiwavelength observations to search for faint and uncataloged counterparts, we derive a radio spectral index that helps disentangle thermal from nonthermal emission and a mean magnetic field through X-ray and TeV data in case of a leptonic scenario. We also search for a spectral connection between the GeV and the TeV regimes with the Fermi-LAT cataloged sources that may be associated with the unidentified HGPS source. We complete the association procedure with catalogs of known objects (supernova remnants, pulsar wind nebulae, H II regions, etc.) and with the source catalogs from instruments whose data are retrieved. Results. The method is applied on two unidentified sources, namely HESS J1427−608 and HESS J1458−608, for which the multiwavelength constraints favor the pulsar wind nebula (PWN) scenario. We model their broadband nonthermal spectra in a leptonic scenario with a magnetic field B ≲ 10 μG, which is consistent with that obtained from ancient PWNe. We place both sources within the context of the TeV PWN population to estimate the spin-down power and the characteristic age of the putative pulsar. We also shed light on two possibly significant γ-ray excesses in the HGPS: the first is located in the south of the unidentified source HESS J1632−478 and the second is spatially coincident with the synchrotron-emitting supernova remnant G28.6−0.1. The multiwavelength counterparts found toward both γ-ray excesses make these promising candidates for being new very-high energy γ-ray sources.

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Section: Application On Hess J1427−608 and Hess J1458−608supporting

confidence: 58%

Section: Multiwavelength Constraintsmentioning

confidence: 53%

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Multiwavelength constraints on the unidentified Galactic TeV sources HESS J1427−608, HESS J1458−608, and new VHE γ-ray source candidates

Devin

Renaud

Lemoine‐Goumard

et al. 2021

A&A

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“…The largest discrepancy in fit values is for the source HESS J1427-608, which had a best-fit spectral index of 2.20 in Aharonian et al (2008). Guo et al (2017) reported on a counterpart seen in Fermi-LAT data at GeV energies with a best fit including the H.E.S.S. data from Aharonian et al (2008) of E −2 over four orders of magnitude in energy with no break in the spectrum, a property unique among currently known TeV sources.…”

Section: Discussionmentioning

confidence: 97%

Search for PeV Gamma-Ray Emission from the Southern Hemisphere with 5 Yr of Data from the IceCube Observatory

Aartsen¹,

Ackermann²,

Adams³

et al. 2020

ApJ

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The measurement of diffuse PeV gamma-ray emission from the Galactic plane would provide information about the energy spectrum and propagation of Galactic cosmic rays, and the detection of a pointlike source of PeV gamma-rays would be strong evidence for a Galactic source capable of accelerating cosmic rays up to at least a few PeV. This paper presents several unbinned maximum-likelihood searches for PeV gamma-rays in the Southern Hemisphere using 5 yr of data from the IceTop air shower surface detector and the in-ice array of the IceCube Observatory. The combination of both detectors takes advantage of the low muon content and deep shower maximum of gamma-ray air showers and provides excellent sensitivity to gamma-rays between ∼0.6 and 100 PeV. Our measurements of pointlike and diffuse Galactic emission of PeV gamma-rays are consistent with the background, so we constrain the angle-integrated diffuse gamma-ray flux from the Galactic plane at 2 PeV to 2.61×10 −19 cm −2 s −1 TeV −1 at 90% confidence, assuming an E −3 spectrum, and we estimate 90% upper limits on pointlike emission at 2 PeV between 10 −21 and 10 −20 cm −2 s −1 TeV −1 for an E −2 spectrum, depending on decl. Furthermore, we exclude unbroken power-law emission up to 2 PeV for several TeV gamma-ray sources observed by the High Energy Spectroscopic System and calculate upper limits on the energy cutoffs of these sources at 90% confidence. We also find no PeV gamma-rays correlated with neutrinos from IceCube's high-energy starting event sample. These are currently the strongest constraints on PeV gamma-ray emission.

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“…RX J1713.7-3946 (Abdo et al 2011;Yuan et al 2011;Zeng et al 2017), RX J0852-4622 (Vela Junior; Tanaka et al 2011), and RCW 86 . These SNRs are believed to be a class of sources with leptonic origin of the γ-ray emission (Yuan et al 2012;Funk 2015;Guo et al 2017).…”

Section: Discussionmentioning

confidence: 99%

Detection of GeV Gamma-Ray Emission in the Direction of HESS J1731-347 with Fermi-LAT

Guo

Xin

Liao

et al. 2018

ApJ

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We report the detection of GeV γ-ray emission from supernova remnant HESS J1731-347 using 9 years of Fermi Large Area Telescope data. We find a slightly extended GeV source in the direction of HESS J1731-347. The spectrum above 1 GeV can be fitted by a power-law with an index of Γ = 1.77 ± 0.14, and the GeV spectrum connects smoothly with the TeV spectrum of HESS J1731-347. Either a hadronic-leptonic or a pure leptonic model can fit the multi-wavelength spectral energy distribution of the source. However, the hard GeV γ-ray spectrum is more naturally produced in a leptonic (inverse Compton scattering) scenario, under the framework of diffusive shock acceleration. We also searched for the GeV γ-ray emission from the nearby TeV source HESS J1729-345. No significant GeV γ-ray emission is found, and upper limits are derived.

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HESS J1427−608: AN UNUSUAL HARD, UNBROKEN Γ-Ray SPECTRUM IN a VERY WIDE ENERGY RANGE

Cited by 9 publications

References 43 publications

Multiwavelength constraints on the unidentified Galactic TeV sources HESS J1427−608, HESS J1458−608, and new VHE γ-ray source candidates

Multiwavelength constraints on the unidentified Galactic TeV sources HESS J1427−608, HESS J1458−608, and new VHE γ-ray source candidates

Search for PeV Gamma-Ray Emission from the Southern Hemisphere with 5 Yr of Data from the IceCube Observatory

Detection of GeV Gamma-Ray Emission in the Direction of HESS J1731-347 with Fermi-LAT

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