A hadronic scenario for HESS J1818–154

Castelletti, G.; Supán, L.; Dubner, G.; Joshi, B. C.; Surnis, Mayuresh

doi:10.1051/0004-6361/201322350

Cited by 14 publications

(22 citation statements)

References 14 publications

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“…Unfortunately, it is usually quite difficult to determine the distance precisely (Acero et al 2016). These distances are often estimated as the kinematic distance of associated molecular clouds detected via CO lines (e.g., Castelletti et al 2013), OH maser, or HI absorption features (e.g., Tian & Leahy 2011. The extinction column density of optical and/or X-ray emission and/or the dispersion measure of the associated radio pulsar can also be used to constrain the distance (e.g., Arzoumanian et al 2011).…”

Section: Model Descriptionmentioning

confidence: 99%

Evolution of High-Energy Particle Distribution in Mature Shell-Type Supernova Remnants

Zeng

Xin

Liu

et al. 2017

ApJ

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Multi-wavelength observations of mature supernova remnants (SNRs), especially with recent advances in γ-ray astronomy, make it possible to constrain energy distribution of energetic particles within these remnants. In consideration of the SNR origin of Galactic cosmic rays and physics related to particle acceleration and radiative processes, we use a simple one-zone model to fit the nonthermal emission spectra of three shell-type SNRs located within 2°on the sky: RX J1713.7−3946, CTB 37B, and CTB 37A. Although radio images of these three sources all show a shell (or half-shell) structure, their radio, X-ray, and γ-ray spectra are quite different, offering an ideal case to explore evolution of energetic particle distribution in SNRs. Our spectral fitting shows that (1) the particle distribution becomes harder with aging of these SNRs, implying a continuous acceleration process, and the particle distributions of CTB 37A and CTB 37B in the GeV range are harder than the hardest distribution that can be produced at a shock via the linear diffusive shock particle acceleration process, so spatial transport may play a role; (2) the energy loss timescale of electrons at the high-energy cutoff due to synchrotron radiation appears to be always a bit (within a factor of a few) shorter than the age of the corresponding remnant, which also requires continuous particle acceleration; (3) double power-law distributions are needed to fit the spectra of CTB 37B and CTB 37A, which may be attributed to shock interaction with molecular clouds.

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Section: Model Descriptionmentioning

confidence: 99%

Evolution of High-Energy Particle Distribution in Mature Shell-Type Supernova Remnants

Zeng

Xin

Liu

et al. 2017

ApJ

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“…No pulsar candidates have been discovered in archival radio observations of the SNR. Castelletti et al (2013) recently discovered a molecular cloud in spatial coincidence with the northern part of the SNR shell and then suggested a hadronic origin of the TeV emission. Although this scenario cannot be excluded, the so far tentative evidence for an interaction between the MC and the shell, the poor morphological match between the MC and the TeV source, and the need to invoke an additional mechanism to explain the X-ray emission makes a hadronic scenario unlikely.…”

Section: Discussionmentioning

confidence: 99%

“…Castelletti et al (2013) placed the SNR at a distance of (4.8 ± 1.0) kpc. At this distance, the angular size of the shell of G 15.4+0.1 (12 ×18 ) corresponds to a physical size of (17 × 15) pc.…”

Section: Age and Evolution Of The Snr G 154+01 And Its Pwnmentioning

confidence: 99%

“…The SNR was reported to have a shell-like morphology with a size of about 14 ×15 and an average spectral index α = −0.6±0.2, indicating that the radio emission is dominated by non-thermal synchrotron emission from the shell. A recent study by Castelletti et al (2013) places the SNR at a distance of (4.8 ± 1.0) kpc and discovered a molecular cloud coincident with the SNR. For the reasons outlined above, this source is a potential emitter of both X-rays and VHE γ rays.…”

Section: Introductionmentioning

confidence: 99%

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HESS J1818–154, a new composite supernova remnant discovered in TeV gamma rays and X-rays

Abramowski¹,

Aharonian²,

Benkhali³

et al. 2014

A&A

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Composite supernova remnants (SNRs) constitute a small subclass of the remnants of massive stellar explosions where non-thermal radiation is observed from both the expanding shell-like shock front and from a pulsar wind nebula (PWN) located inside of the SNR. These systems represent a unique evolutionary phase of SNRs where observations in the radio, X-ray, and γ-ray regimes allow the study of the co-evolution of both these energetic phenomena. In this article, we report results from observations of the shell-type SNR G 15.4+0.1 performed with the High Energy Stereoscopic System (H.E.S.S.) and XMM-Newton. A compact TeV γ-ray source, HESS J1818−154, located in the center and contained within the shell of G 15.4+0.1 is detected by H.E.S.S. and featurs a spectrum best represented by a power-law model with a spectral index of −2.3 ± 0.3 stat ± 0.2 sys and an integral flux of F(>0.42 TeV) = (0.9 ± 0.3 stat ± 0.2 sys ) × 10 −12 cm −2 s −1 . Furthermore, a recent observation with XMM-Newton reveals extended X-ray emission strongly peaked in the center of G 15.4+0.1. The X-ray source shows indications of an energydependent morphology featuring a compact core at energies above 4 keV and more extended emission that fills the entire region within the SNR at lower energies. Together, the X-ray and VHE γ-ray emission provide strong evidence of a PWN located inside the shell of G 15.4+0.1 and this SNR can therefore be classified as a composite based on these observations. The radio, X-ray, and γ-ray emission from the PWN is compatible with a one-zone leptonic model that requires a low average magnetic field inside the emission region. An unambiguous counterpart to the putative pulsar, which is thought to power the PWN, has been detected neither in radio nor in X-ray observations of G 15.4+0.1.

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“…Since the profiles are clearly non-gaussian, the listed parameters are only mean representative values. Additionally, we followed the procedure presented in Castelletti et al (2013) to calculate the H 2 column density of the identified molecular material and used this value, together with the corresponding distance that we derived for each cloud, to compute the total mass of the clouds. For clouds A, B, and C we assumed regions (elliptical for A, and circular for B and C) with physical sizes of approximately 2 .5 × 6 , 3 .5 and 3 in diameter, respectively.…”

Section: Distance Constraintsmentioning

confidence: 99%

Radio and X-ray properties of the source G29.37+0.1 linked to HESS J1844−030

Castelletti

Supán

Petriella

et al. 2017

A&A

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Aims. We report on the first detailed multiwavelength study of the radio source G29.37+0.1, which is an as-yet-unclassified object linked to the very-high-energy γ-emitting source HESS J1844−030. The origin of the multiwavelength emission toward G29.37+0.1 has not been clarified so far, leaving open the question about the physical relationship between these sources. Methods. Using observations carried out with the Giant Metrewave Radio Telescope (GMRT), we performed high-quality fullsynthesis imaging at 610 MHz of the field containing G29.37+0.1. The obtained data, combined with observations at 1400 MHz from The Multi-Array Galactic Plane Imaging Survey (MAGPIS) were used to investigate in detail the properties of its radio emission. Additionally, we reprocessed archival data obtained with the XMM-Newton and Chandra observatories in order to get a multiwavelength view of this unusual source. Results. The radio source G29.37+0.1 mainly consists of a bright twisted structure, named the S-shaped feature. The high sensitivity of the new GMRT observations allowed the identification of potential lobes, jets, and a nuclear central region in the S-shaped morphology of G29.37+0.1. We also highlight the detection of diffuse and low surface brightness emission enveloping the brightest emitting regions. The brightest emission in G29.37+0.1 has a radio synchrotron spectral index α=0.59±0.09. Variations in the spectral behaviour are observed across the whole radio source with the flattest spectral features in the central nuclear and jets components (α∼0.3). These results lead us to conclude that the brightest radio emission from G29.37+0.1 likely represents a newly recognized radio galaxy. The identification of optical and infrared counterparts to the emission arising from the core of G29.37+0.1 strengthens our interpretation of an extragalactic origin of the radio emission. We performed several tests to explain the physical mechanism responsible for the observed X-ray emission, which appears overlapping the northeastern part of the radio emission. Our spectral analysis demonstrated that a non-thermal origin for the X-ray emission compatible with a pulsar wind nebula is quite possible. The analysis of the spatial distribution of the CO gas revealed the presence of a complex of molecular clouds located in projection adjacent to the radio halo emission and probably interacting with it. We propose that the faint halo represents a composite supernova remnant with a pulsar powered component given by the diffuse X-ray emission superimposed along the line of sight to the radio galaxy. Further broadband observations of HESS J1844−030 are needed to disentangle its origin, although its shape and position suggest an extragalactic origin connected to G29.37+0.1.

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A hadronic scenario for HESS J1818–154

Cited by 14 publications

References 14 publications

Evolution of High-Energy Particle Distribution in Mature Shell-Type Supernova Remnants

Evolution of High-Energy Particle Distribution in Mature Shell-Type Supernova Remnants

HESS J1818–154, a new composite supernova remnant discovered in TeV gamma rays and X-rays

Radio and X-ray properties of the source G29.37+0.1 linked to HESS J1844−030

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