The interstellar medium and the massive stellar content towards the SNR G18.1−0.1 and neighbouring H ii regions

Paron, S.; Weidmann, W. A.; Ortega, M. E.; Colombo, J. F. Albacete; Pichel, A.

doi:10.1093/mnras/stt837

Cited by 18 publications

(52 citation statements)

References 42 publications

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“…Notably, such collisions between molecular clouds are thought to generate OB stars, filamentary clouds, dense cores and complex velocity distribution. In our region of study, Paron et al (2013) in fact detected several O and B stars next to the IR bubble N22, N21 and the UC Hii G018.15-00.28 towards the molecular gas R1a component.…”

Section: Discussionmentioning

confidence: 52%

“…From Fig. 9, we noted that the molecular gas in R4a (shown in green) appeared to be part of the putative molecular shell GSH G018.2-0.1+53 suggested by Paron et al (2013) whereas the gas in R4b (in red) appeared isolated. However, their similar morphologies as shown by the overlap of the two components (in yellow) the similarities of the 13 CO(1-0), CS, and NH3 spectral lines may indicate some association.…”

Section: Region R4mentioning

confidence: 92%

“…The region covered by our 7mm survey is shown in black dashed box. The putative molecular shell GSH 18.1-0.2+53 (Paron et al 2013) is shown in purple dashed ellipse (see online version) in the middle-left panel. Finally, the red dashed circle in the middle right panel represents the region whose mass and density have been calculated (see section 4.2).…”

Section: Overviewmentioning

confidence: 99%

“…Therefore, the progenitor SNR of PSR J1826−1334 may contribute to the HESS J1826−130 TeV emission. Paron et al (2013) argued the distance of SNR G018.2−0.1 to be d = 4 kpc based on its possible association with the nearby Hii regions. Its small projected radius r ∼4 pc would imply a very young SNR with age < 1000 yr. By comparing our CO(1-0) column density the those derived from X-ray measurements NH = 7.2 × 10 22 cm −2 (Sugizaki et al 2001) and NH = 5.7 × 10 22 cm −2 (Leahy, Green & Tian 2014), we would argue an SNR distance greater than 4 kpc, consistent with the distance estimate from Leahy, Green & Tian (2014).…”

Section: Crs From the Progenitor Snr Of Psr J1826-1334mentioning

confidence: 99%

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ISM gas studies towards the TeV PWN HESS J1825−137 and northern region

Voisin¹,

Rowell²,

Burton³

et al. 2016

Mon. Not. R. Astron. Soc.

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HESS J1825−137 is a pulsar wind nebula (PWN) whose TeV emission extends across ∼ 1 deg. Its large asymmetric shape indicates that its progenitor supernova interacted with a molecular cloud located in the north of the PWN as detected by previous CO Galactic survey (e.g Lemiere, Terrier & Djannati-Ataï 2006).Here we provide a detailed picture of the ISM towards the region north of HESS J1825−137, with the analysis of the dense molecular gas from our 7mm and 12mm Mopra survey and the more diffuse molecular gas from the Nanten CO(1-0) and GRS 13 CO(1-0) surveys. Our focus is the possible association between HESS J1825−137 and the unidentified TeV source to the north, HESS J1826−130. We report several dense molecular regions whose kinematic distance matched the dispersion measured distance of the pulsar. Among them, the dense molecular gas located at (RA, Dec)=(18.421h,−13.282 • ) shows enhanced turbulence and we suggest that the velocity structure in this region may be explained by a cloud-cloud collision scenario.Furthermore, the presence of a Hα rim may be the first evidence of the progenitor SNR of the pulsar PSR J1826-1334 as the distance between the Hα rim and the TeV source matched with the predicted SNR radius R SNR ∼ 120 pc.From our ISM study, we identify a few plausible origins of the HESS J1826−130 emission, including the progenitor SNR of PSR J1826−1334 and the PWN G018.5−0.4 powered by PSR J1826−1256. A deeper TeV study however, is required to fully identify the origin of this mysterious TeV source.Key words: molecular data -pulsars: individual: PSR J1826−1334 -ISM: cloudscosmic-rays -gamma-rays: ISM. INTRODUCTIONHESS J1825−137 is one of the brightest and most extensive pulsar wind nebulae (PWNe) detected in TeV γ-rays (Aharonian et al. 2006). It is powered by the high spin-down power (ĖSD = 2.8 × 10 36 erg/s) pulsar PSR J1826−1334 with a dispersion measure distance of 3.9±0.4 kpc and characteristic age τc ∼ 20 kyr.PWNe represent a significant fraction of the Galactic TeV γ-ray source population. They convert a varying fraction of their pulsars' spin down energyĖSD into high energy E-mail:fabien.voisin@adelaide.edu.au (AVR); fabien.voisin@adelaide.edu.au (ANO) electrons. The electron flow is temporally randomized and re-accelerated at a termination shock resulting from pressure from the surrounding interstellar medium (ISM). InverseCompton (IC) up-scattering of soft photons then leads to TeV γ-rays, and associated synchrotron radio to X-ray emission.The morphology of PWNe can be heavily influenced by the ISM. The interaction of the progenitor supernova shock with adjacent molecular clouds can lead to a reverse shock propagating back into the PWN (Blondin, Chevalier & Frierson 2001), giving rise to an asymmetry in the radio, X-ray and γ-ray emission that can trail away from the pulsar along the pulsar-molecular cloud axis.HESS J1825−137 is an excellent example of this situa- Lemiere, Terrier & Djannati-Ataï (2006), with the bulk of the TeV γ-ray extending up to a degree south of the pulsar. In...

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Section: Discussionmentioning

confidence: 52%

Section: Region R4mentioning

confidence: 92%

Section: Overviewmentioning

confidence: 99%

Section: Crs From the Progenitor Snr Of Psr J1826-1334mentioning

confidence: 99%

See 2 more Smart Citations

ISM gas studies towards the TeV PWN HESS J1825−137 and northern region

Voisin¹,

Rowell²,

Burton³

et al. 2016

Mon. Not. R. Astron. Soc.

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show abstract

“…This PWN is probably powered by the pulsar PSR J1826−1256, which lies within the VHE emission region 5 .4 offset from its centroid, and now is notable for being one of the brightest radio-quiet γ-ray pulsars (Acero et al 2015). Nevertheless, within the extension of HESS J1826−130 there are other potential sources of energetic particles capable to power the TeV emission, such as radio SNRs and HII regions (Paron et al 2013), and this fact hampers a decisive conclusion on the origin of the γ-rays.…”

Section: Introductionmentioning

confidence: 99%

A new study towards PSR J1826–1334 and PSR J1826–1256 in the region of HESS J1825–137 and HESS J1826–130

Duvidovich

Giacani²,

Castelletti³

et al. 2019

A&A

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Aims. The goal of this paper is to detect synchrotron emission from the relic electrons of the crushed pulsar wind nebula (PWN) HESS J1825−137 and to investigate the origin of the γ-ray emission from HESS J1826−130. Methods. The study of HESS J1825−137 was carried out on the basis of new radio observations centred at the position of PSR J1826−1334 performed with the Karl G. Jansky Very Large Array at 1.4 GHz in configurations B and C. To investigate the nature of HESS J1826−130, we reprocessed unpublished archival data obtained with XMM-Newton. Results. The new radio continuum image towards PSR J1826−1334 reveals a bright radio source, with the pulsar located in its centre, which suggests that this feature could be the radio counterpart of the compact component of the PWN detected at high energy. The new 1.4 GHz radio data do not reveal emission with an extension comparable with that observed in γ-rays for the HESS J1825−137 source. On the other hand, the XMM-Newton study of the region including PSR J1826−1256 reveals an elongated non-thermal X-ray emitting nebula with the pulsar located in the northern border and a tail towards the peak of the very high energy source. The spectrum is characterized by a power law with a photon index going from 1.6 around the pulsar to 2.7 in the borders of the nebula, a behaviour consistent with synchrotron cooling of electrons. From our X-ray analysis we propose that HESS J1826−130 is likely produced by the PWN powered by PSR J1826−1256 via the inverse Compton mechanism.

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Using 3D Voronoi grids in radiative transfer simulations

Camps

Baes

Saftly

2013

A&A

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Context. Probing the structure of complex astrophysical objects requires effective three-dimensional (3D) numerical simulation of the relevant radiative transfer (RT) processes. As with any numerical simulation code, the choice of an appropriate discretization is crucial. Adaptive grids with cuboidal cells such as octrees have proven very popular; however, several recently introduced hydrodynamical and RT codes are based on a Voronoi tessellation of the spatial domain. An unstructured grid of this nature poses new challenges in laying down the rays (straight paths) needed in RT codes. Aims. We show that it is straightforward to implement accurate and efficient RT on 3D Voronoi grids. Methods. We present a method for computing straight paths between two arbitrary points through a 3D Voronoi grid in the context of a RT code. We implement this grid in our RT code SKIRT, using the open source library Voro++ to obtain the relevant properties of the Voronoi grid cells based solely on the generating points. We compare the results obtained through the Voronoi grid with those generated by an octree grid for two synthetic models, and we perform the well-known Pascucci RT benchmark using the Voronoi grid. Results. The presented algorithm produces correct results for our test models. Shooting photon packages through the geometrically much more complex 3D Voronoi grid is only about three times slower than the equivalent process in an octree grid with the same number of cells, while in fact the total number of Voronoi grid cells may be lower for an equally good representation of the density field. Conclusions. The benefits of using a Voronoi grid in RT simulation codes will often outweigh the somewhat slower performance.

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The interstellar medium and the massive stellar content towards the SNR G18.1−0.1 and neighbouring H ii regions

Cited by 18 publications

References 42 publications

ISM gas studies towards the TeV PWN HESS J1825−137 and northern region

ISM gas studies towards the TeV PWN HESS J1825−137 and northern region

A new study towards PSR J1826–1334 and PSR J1826–1256 in the region of HESS J1825–137 and HESS J1826–130

Using 3D Voronoi grids in radiative transfer simulations

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