scholarly journals Connecting the ISM to TeV PWNe and PWN candidates

2019 ◽  
Vol 36 ◽  
Author(s):  
F. J. Voisin ◽  
G. P. Rowell ◽  
M. G. Burton ◽  
Y. Fukui ◽  
H. Sano ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Gamma Ray ◽  
Galactic Plane ◽  
Cosmic Ray ◽  
Molecular Gas ◽  
Pulsar Wind Nebulae ◽  
Density Estimates ◽  
Pulsar Wind

AbstractWe investigate the interstellar medium towards seven TeV gamma-ray sources thought to be pulsar wind nebulae using Mopra molecular line observations at 7 mm [CS(1–0), SiO(1–0, v = 0)], Nanten CO(1–0) data and the Southern Galactic Plane Survey/GASS Hisurvey. We have discovered several dense molecular clouds co-located to these TeV gamma-ray sources, which allows us to search for cosmic rays coming from progenitor SNRs or, potentially, from pulsar wind nebulae. We notably found SiO(1–0, v = 0) emission towards HESS J1809–193, highlighting possible interaction between the adjacent supernova remnant SNR G011.0–0.0 and the molecular cloud atd∼ 3.7 kpc. Using morphological features, and comparative studies of our column densities with those obtained from X-ray measurements, we claim a distanced∼ 8.6 − 9.7kpc for SNR G292.2–00.5,d∼ 3.5 − 5.6 kpc for PSR J1418–6058 andd∼ 1.5 kpc for the new SNR candidate found towards HESS J1303–631. From our mass and density estimates of selected molecular clouds, we discuss signatures of hadronic/leptonic components from pulsar wind nebulae and their progenitor SNRs. Interestingly, the molecular gas, which overlaps HESS J1026–582 atd∼ 5 kpc, may support a hadronic origin. We find however that this scenario requires an undetected cosmic-ray accelerator to be located atd< 10 pc from the molecular cloud. For HESS J1809–193, the cosmic rays which have escaped SNR G011.0–0.0 could contribute to the TeV gamma-ray emission. Finally, from the hypothesis that at most 20% the pulsar spin down power could be converted into CRs, we find that among the studied pulsar wind nebulae, only those from PSR J1809–1917 could potentially contribute to the TeV emission.

scholarly journals Fermi-LAT Detection of Extended Gamma-Ray Emission in the Vicinity of SNR G045.7-00.4: Evidence of Escaping Cosmic Rays Interacting with the Surrounding Molecular Clouds

2021 ◽  
Vol 923 (1) ◽  
pp. 106
Author(s):  
Hai-Ming Zhang ◽  
Ruo-Yu Liu ◽  
Yang Su ◽  
Hui Zhu ◽  
Shao-Qiang Xi ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Supernova Remnant ◽  
Milky Way ◽  
Gamma Ray ◽  
Molecular Gas ◽  
Western Boundary ◽  
Large Area ◽  
Gamma Ray Emission

Abstract We present an analysis of Fermi Large Area Telescope data of the gamma-ray emission in the vicinity of a radio supernova remnant (SNR), G045.7-00.4. To study the origin of the gamma-ray emission, we also make use of the CO survey data of Milky Way Imaging Scroll Painting to study the massive molecular gas complex that surrounds the SNR. The whole size of the gigaelectronvolt emission is significantly larger than that of the radio morphology. Above 3 GeV, the gigaelectronvolt emission is resolved into two sources: one is spatially consistent with the position of the SNR with a size comparable to that of the radio emission, and the other is located outside of the western boundary of the SNR and spatially coincident with the densest region of the surrounding molecular cloud. We suggest that the gigaelectronvolt emission of the western source may arise from cosmic rays (CRs) that have escaped the SNR and illuminated the surrounding molecular cloud. We find that the gamma-ray spectra of the western source can be consistently explained by this scenario with a total energy of ∼1050 erg in escaping CRs assuming the escape is isotropic.

scholarly journals An interacting molecular cloud scenario for production of gamma-rays and neutrinos from MAGIC J1835-069, and MAGIC J1837-073

2021 ◽  
Vol 81 (5) ◽  
Author(s):  
Prabir Banik ◽  
Arunava Bhadra
Keyword(s):  
Cosmic Rays ◽  
Gamma Rays ◽  
Molecular Cloud ◽  
Gamma Ray ◽  
Galactic Plane ◽  
Cosmic Ray ◽  
Maximum Energy ◽  
Hadronic Interactions ◽  
Extended Sources ◽  
First Time

AbstractRecently the MAGIC telescope observed three TeV gamma-ray extended sources in the galactic plane in the neighborhood of radio SNR G24.7+0.6. Among them, the PWN HESS J1837-069 was detected earlier by the HESS observatory during its first galactic plane survey. The other two sources, MAGIC J1835-069 and MAGIC J1837-073 are detected for the first time at such high energies. Here we shall show that the observed gamma-rays from the SNR G24.7+0.6 and the HESS J1837-069 can be explained in terms of hadronic interactions of the PWN/SNR accelerated cosmic rays with the ambient matter. We shall further demonstrate that the observed gamma-rays from the MAGIC J1837-073 can be interpreted through hadronic interactions of runaway cosmic-rays from PWN HESS J1837-069 with the molecular cloud at the location of MAGIC J1837-073. No such association has been found between MAGIC J1835-069 and SNR G24.7+0.6 or PWN HESS J1837-069. We have examined the maximum energy attainable by cosmic-ray particles in the SNR G24.7+0.6/ PWN HESS J1837-069 and the possibility of their detection with future gamma-ray telescopes. The study of TeV neutrino emissions from the stated sources suggests that the HESS J1837-069 should be detected by IceCube Gen-2 neutrino telescope in a few years of observation.

scholarly journals The population of TeV pulsar wind nebulae in the H.E.S.S. Galactic Plane Survey

2018 ◽  
Vol 612 ◽  
pp. A2 ◽  
Author(s):  
◽  
H. Abdalla ◽  
A. Abramowski ◽  
F. Aharonian ◽  
F. Ait Benkhali ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Galactic Plane ◽  
High Energy ◽  
Pulsar Wind Nebulae ◽  
Upper Limits ◽  
Very High Energy ◽  
Consistent Picture ◽  
Pulsar Wind ◽  
Asymmetric Environment ◽  
First Time

The nine-year H.E.S.S. Galactic Plane Survey (HGPS) has yielded the most uniform observation scan of the inner Milky Way in the TeV gamma-ray band to date. The sky maps and source catalogue of the HGPS allow for a systematic study of the population of TeV pulsar wind nebulae found throughout the last decade. To investigate the nature and evolution of pulsar wind nebulae, for the first time we also present several upper limits for regions around pulsars without a detected TeV wind nebula. Our data exhibit a correlation of TeV surface brightness with pulsar spin-down power Ė. This seems to be caused both by an increase of extension with decreasing Ė, and hence with time, compatible with a power law RPWN(Ė) ~Ė−0.65±0.20, and by a mild decrease of TeV gamma-ray luminosity with decreasing Ė, compatible with L1−10 TeV ~Ė0.59±0.21. We also find that the offsets of pulsars with respect to the wind nebula centre with ages around 10  kyr are frequently larger than can be plausibly explained by pulsar proper motion and could be due to an asymmetric environment. In the present data, it seems that a large pulsar offset is correlated with a high apparent TeV efficiency L1−10 TeV∕Ė. In addition to 14 HGPS sources considered firmly identified pulsar wind nebulae and 5 additional pulsar wind nebulae taken from literature, we find 10 HGPS sources that are likely TeV pulsar wind nebula candidates. Using a model that subsumes the present common understanding of the very high-energy radiative evolution of pulsar wind nebulae, we find that the trends and variations of the TeV observables and limits can be reproduced to a good level, drawing a consistent picture of present-day TeV data and theory.

scholarly journals The Mopra Southern Galactic Plane CO Survey

2013 ◽  
Vol 30 ◽  
Author(s):  
Michael G. Burton ◽  
C. Braiding ◽  
C. Glueck ◽  
P. Goldsmith ◽  
J. Hawkes ◽  
...  
Keyword(s):  
Molecular Clouds ◽  
Gamma Ray ◽  
Galactic Plane ◽  
Molecular Gas ◽  
Number Density ◽  
Analysis Methodology ◽  
The Galaxy ◽  
First Results ◽  
Molecular Masses ◽  
Velocity Channel

AbstractWe present the first results from a new carbon monoxide (CO) survey of the southern Galactic plane being conducted with the Mopra radio telescope in Australia. The 12CO, 13CO, and C18O J = 1–0 lines are being mapped over the $l = 305^{\circ }\text{--} 345^{\circ }, b = \pm 0.5^{\circ }$ portion of the fourth quadrant of the Galaxy, at 35 arcsec spatial and 0.1 km s−1 spectral resolution. The survey is being undertaken with two principal science objectives: (i) to determine where and how molecular clouds are forming in the Galaxy and (ii) to probe the connection between molecular clouds and the ‘missing’ gas inferred from gamma-ray observations. We describe the motivation for the survey, the instrumentation and observing techniques being applied, and the data reduction and analysis methodology. In this paper, we present the data from the first degree surveyed, $l = 323^{\circ } \text{--} 324^{\circ }, b = \pm 0.5^{\circ }$. We compare the data to the previous CO survey of this region and present metrics quantifying the performance being achieved; the rms sensitivity per 0.1 km s−1 velocity channel is ~1.5 K for ${\rm ^{12}CO}$ and ~0.7 K for the other lines. We also present some results from the region surveyed, including line fluxes, column densities, molecular masses, ${\rm ^{12}CO/^{13}CO}$ line ratios, and ${\rm ^{12}CO}$ optical depths. We also examine how these quantities vary as a function of distance from the Sun when averaged over the 1 square degree survey area. Approximately 2 × 106M⊙ of molecular gas is found along the G323 sightline, with an average H2 number density of $n_{\text{H}_2} \sim 1$ cm−3 within the Solar circle. The CO data cubes will be made publicly available as they are published.

scholarly journals New hard X-ray sources discovered in the ongoing INTEGRAL Galactic plane survey after 14 yr of observations

2017 ◽  
Vol 470 (1) ◽  
pp. 512-516 ◽  
Author(s):  
Roman A. Krivonos ◽  
Sergey S. Tsygankov ◽  
Ilya A. Mereminskiy ◽  
Alexander A. Lutovinov ◽  
Sergey Yu. Sazonov ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Gamma Ray ◽  
Galactic Plane ◽  
Cataclysmic Variables ◽  
Galactic Nuclei ◽  
Pulsar Wind Nebulae ◽  
X Ray ◽  
Sky Survey ◽  
The Galaxy ◽  
Pulsar Wind

Abstract The International Gamma-Ray Astrophysics Laboratory (INTEGRAL) continues to successfully work in orbit after its launch in 2002. The mission provides the deepest ever survey of hard X-ray sources throughout the Galaxy at energies above 20 keV. We report on a catalogue of new hard X-ray source candidates based on the latest sky maps comprising 14 yr of data acquired with the IBIS telescope onboard INTEGRAL in the Galactic Plane (|b| &lt; 17.5°). The current catalogue includes in total 72 hard X-ray sources detected at S/N &gt; 4.7σ and not known to previous INTEGRAL surveys. Among them, 31 objects have also been detected in the on-going all-sky survey by the BAT telescope of the Swift observatory. For 26 sources on the list, we suggest possible identifications: 21 active galactic nuclei, two cataclysmic variables, two isolated pulsars or pulsar wind nebulae and one supernova remnant; 46 sources from the catalogue remain unclassified.

scholarly journals The low cosmic-ray density in the Polaris Flare

2021 ◽  
Vol 21 (10) ◽  
pp. 246
Author(s):  
Zhi-Wei Cui ◽  
Rui-Zhi Yang ◽  
Bing Liu
Keyword(s):  
Molecular Cloud ◽  
Molecular Clouds ◽  
Column Density ◽  
Galactic Plane ◽  
Cosmic Ray ◽  
Giant Molecular Cloud ◽  
Large Gradient ◽  
Ray Density ◽  
Density Map

Abstract We reported the γ-ray observation towards the giant molecular cloud Polaris Flare. Together with the dust column density map, we derived the cosmic ray (CR) density and spectrum in this cloud. Compared with the CR measured locally, the CR density in the Polaris Flare is significantly lower and the spectrum is softer. Such a different CR spectrum reveals either a rather large gradient of CR distribution in the direction perpendicular to the Galactic plane or a suppression of CR inside molecular clouds.

scholarly journals Constraining the cosmic ray spectrum in the vicinity of the supernova remnant W28: from sub-GeV to multi-TeV energies

2020 ◽  
Vol 635 ◽  
pp. A40
Author(s):  
V. H. M. Phan ◽  
S. Gabici ◽  
G. Morlino ◽  
R. Terrier ◽  
J. Vink ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Molecular Clouds ◽  
Supernova Remnants ◽  
Supernova Remnant ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
Ionization Rate ◽  
High Energy ◽  
Radio Waves ◽  
X Ray

Context. Supernova remnants interacting with molecular clouds are ideal laboratories to study the acceleration of particles at shock waves and their transport and interactions in the surrounding interstellar medium. Aims. Here, we focus on the supernova remnant W28, which over the years has been observed in all energy domains from radio waves to very-high-energy gamma rays. The bright gamma-ray emission detected from molecular clouds located in its vicinity revealed the presence of accelerated GeV and TeV particles in the region. An enhanced ionization rate has also been measured by means of millimeter observations, but such observations alone cannot tell us whether the enhancement is due to low-energy (MeV) cosmic rays (either protons or electrons) or the X-ray photons emitted by the shocked gas. The goal of this study is to determine the origin of the enhanced ionization rate and to infer from multiwavelength observations the spectrum of cosmic rays accelerated at the supernova remnant shock in an unprecedented range spanning from MeV to multi-TeV particle energies. Methods. We developed a model to describe the transport of X-ray photons into the molecular cloud, and we fitted the radio, millimeter, and gamma-ray data to derive the spectrum of the radiating particles. Results. The contribution from X-ray photons to the enhanced ionization rate is negligible, and therefore the ionization must be due to cosmic rays. Even though we cannot exclude a contribution to the ionization rate coming from cosmic-ray electrons, we show that a scenario where cosmic-ray protons explain both the gamma-ray flux and the enhanced ionization rate provides the most natural fit to multiwavelength data. This strongly suggests that the intensity of CR protons is enhanced in the region for particle energies in a very broad range covering almost six orders of magnitude: from ≲100 MeV up to several tens of TeV.

“KAGONMA” NH3 mapping observations of molecular clouds with Nobeyama 45m telescope

2018 ◽  
Vol 14 (S345) ◽  
pp. 353-354
Author(s):  
T. Murase ◽  
T. Handa ◽  
M. Maebata ◽  
Z. Yang ◽  
Y. Hirata ◽  
...  
Keyword(s):  
Temperature Gradient ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Galactic Plane ◽  
Evolutionary Process ◽  
Molecular Gas ◽  
Gas Temperature ◽  
Dense Molecular Cloud ◽  
Temperature Maps ◽  
Galactic Object

AbstractIn the collapsing phase of a molecular cloud, the molecular gas temperature is a key to understand the evolutionary process from a dense molecular cloud to stars. In order to know this, mapping observations in NH3 lines are required. Therefore, we made them based on the FUGIN (FOREST Unbiased Galactic plane Imaging survey with Nobeyama 45m telescope). The 6 maps were observed in NH3 (J,K) = (1,1), (2,2), (3,3) and H2O maser lines and obtained temperature maps; some show temperature gradient in a cloud. Additionally 72 cores were observed. These candidates were called as KAGONMA or KAG objects as abbreviation of KAgoshima Galactic Object survey with Nobeyama 45-M telescope in Ammonia lines. We show the results of two regions in W33 and discuss their astrophysical properties.

scholarly journals The contribution of Galactic TeV pulsar wind nebulae to Fermi-LAT diffuse emission

2021 ◽  
Author(s):  
Vittoria Vecchiotti ◽  
Giulia Pagliaroli ◽  
Francesco Villante
Keyword(s):  
Cosmic Rays ◽  
Energy Range ◽  
Spectral Index ◽  
Large Scale ◽  
Galactic Center ◽  
Galactic Plane ◽  
Diffuse Emission ◽  
Pulsar Wind Nebulae ◽  
Γ Ray ◽  
Pulsar Wind

Abstract The large-scale diffuse γ−ray flux observed by Fermi-LAT in the 1-100 GeV energy range, parameterized as ∝ E−Γ, has a spectral index Γ that depends on the distance from the Galactic center. This feature, if attributed to the diffuse emission produced by cosmic rays (CR) interactions with the interstellar gas, can be interpreted as the evidence of a progressive CR spectral hardening towards the Galactic center. This interpretation challenges the standard cosmic rays diffusion paradigm. We report on the implications of TeV Pulsar Wind Nebulae observed by the HESS Galactic Plane Survey in the 1-100 TeV energy range for the interpretation of Fermi-LAT data. We argue that a relevant fraction of this population cannot be resolved by Fermi-LAT in the GeV domain providing a relevant contribution to the large-scale diffuse emission, viz. the 30% of the total diffuse γ-ray emission in the inner Galaxy. This additional component naturally accounts for a large part of the spectral index variation observed by Fermi-LAT, weakening the evidence of CR spectral hardening in the inner Galaxy.

scholarly journals Introducing the HD+B model for pulsar wind nebulae: a hybrid hydrodynamics/radiative approach

2020 ◽  
Vol 494 (3) ◽  
pp. 4357-4370
Author(s):  
B Olmi ◽  
D F Torres
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Theoretical Modelling ◽  
X Rays ◽  
Pulsar Wind Nebulae ◽  
New Approach ◽  
Energy Gamma ◽  
Radiative Model ◽  
Pulsar Wind

ABSTRACT Identification and characterization of a rapidly increasing number of pulsar wind nebulae is, and will continue to be, a challenge of high-energy gamma-ray astrophysics. Given that such systems constitute -by far- the most numerous expected population in the TeV regime, such characterization is important not only to learn about the sources per se from an individual and population perspective, but also to be able to connect them with observations at other frequencies, especially in radio and X-rays. Also, we need to remove the emission from nebulae in highly confused regions of the sky for revealing other underlying emitters. In this paper, we present a new approach for theoretical modelling of pulsar wind nebulae: a hybrid hydrodynamic-radiative model able to reproduce morphological features and spectra of the sources, with relatively limited numerical cost.

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