N. Maxted

A 7 mm line survey of the shocked and disrupted molecular gas towards the W28 field TeV gamma-ray sources

We present 7 mm Mopra observations of the dense molecular gas towards the W28 supernova remnant (SNR) field, following a previous 12 mm line survey of this region. These observations take advantage of the 7 mm beam size to probe the dense and disrupted gas in the region at ∼1 arcmin scales. Our observations are focused towards the north-eastern (NE) HESS J1801−233 and southern HESS J1800−240 B TeV gamma-ray sources, with slightly less observations towards HESS J1800−240 A and C. Using the CS (1–0) transition we reveal multiple regions of dense gas, inline image cm−3. We report the discovery of dense gas towards HESS J1800−240 C, at the site of a 1720 MHz OH maser. The NE molecular cloud is known to be disrupted; many 1720 MHz OH masers and broad CO line emission are detected at the rim of W28. Here, we reveal this shock interaction region contains generally extended clumpy CS, as well as clumpy SiO and CH3OH emission with broad line profiles. The full width at half maximum (FWHM) of the molecular lines extend up to 18 km s−1 on the W28 side of the NE cloud. The detection of SiO towards maser clumps OH C, D, E and F provides further evidence of the shocked conditions in the NE cloud. Several other lines associated with star formation are also detected towards the southern source, notably the energetic H ii complex G5.89−0.39. The spatial match of dense gas with the TeV emission further supports the cosmic ray (CR) origin for the gamma-rays. We estimate the mass of several extended dense clouds within the field and predict the TeV flux from the dense cloud components. The predicted fluxes are of the order of 10−14 to 10−13 photons cm−2 s−1, which should be detectable and possibly resolved by a future TeV instrument, such as the Cherenkov Telescope Array.

3 to 12 millimetre studies of dense gas towards the western rim of supernova remnant RX J1713.7-3946

The young X-ray and gamma-ray-bright supernova remnant RX J1713.7-3946 (SNR G347.3-0.5) is believed to be associated with molecular cores that lie within regions of the most intense TeV emission. Using the Mopra telescope, four of the densest cores were observed using high critical density tracers such as CS(J= 10, J= 21) and its isotopologue counterparts, NH₃(1, 1) and (2, 2) inversion transitions and N₂H⁺(J= 10) emission, confirming the presence of dense gas ≥10⁴cm⁻³ in the region. The mass estimates for Core C range from 40 (from CS) to 80 M⊙ (from NH₃ and N₂H⁺), an order of magnitude smaller than published mass estimates from CO(J= 1-0) observations. We also modelled the energy-dependent diffusion of cosmic ray protons accelerated by RX J1713.7-3946 into Core C, approximating the core with average density and magnetic field values. We find that for considerably suppressed diffusion coefficients (factors χ= 10⁻³ down to 10⁻⁵ the Galactic average), low-energy cosmic rays can be prevented from entering the inner core region. Such an effect could lead to characteristic spectral behaviour in the GeV to TeV gamma-ray and multi-keV X-ray fluxes across the core. These features may be measurable with future gamma-ray and multi-keV telescopes offering arcminute or better angular resolution, and can be a novel way to understand the level of cosmic ray acceleration in RX J1713.7-3946 and the transport properties of cosmic rays in the dense molecular cores.

Interstellar gas towards CTB 37A and the TeV gamma-ray source HESS J1714−385

Observations of dense molecular gas towards the supernova remnants CTB 37A (G348.5+0.1) and G348.5-0.0 were carried out using the Mopra and Nanten2 radio telescopes. We present CO(2-1) and CS(1-0) emission maps of a region encompassing the CTB 37A TeV gamma-ray emission, HESS J1714-385, revealing regions of dense gas within associated molecular clouds. Some gas displays good overlap with gamma-ray emission, consistent with hadronic gamma-ray emission scenarios. Masses of gas towards the HESS J1714-385 TeV gamma-ray emission region were estimated, and were of the order of 10^3-10^4 solar masses. In the case of a purely hadronic origin for the gamma-ray emission, the cosmic ray flux enhancement is ~80-1100 times the local solar value. This enhancement factor and other considerations allow a discussion of the age of CTB 37A, which is consistent with ~10^4 yr.

A Detailed Study of the Interstellar Protons toward the TeV γ-Ray SNR RX J0852.0–4622 (G266.2–1.2, Vela Jr.): The Third Case of the γ-Ray and ISM Spatial Correspondence

We present a new analysis of the interstellar protons toward the TeV

Dense gas towards the RX J1713.7-3946 supernova remnant

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Discovery of new TeV supernova remnant shells in the Galactic plane with H.E.S.S.

-ray SNR RX J0852.0

Ammonia excitation imaging of shocked gas towards the W28 gamma-ray source HESS J1801−233

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Upper limits on gamma-ray emission from Supernovae serendipitously observed with H.E.S.S

4622 (G266.2

Radio Evolution of Supernova Remnants Including Nonlinear Particle Acceleration: Insights from Hydrodynamic Simulations

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Probing the local environment of the supernova remnant HESS J1731−347 with CO and CS observations

1.2, Vela Jr.). We used the NANTEN2