Spitzer observations of supernova remnants: II. Physical conditions and comparison with HH7 and HH54

Abstract

We have studied the shock-excited molecular regions associated with four supernova remnants (SNRs) - IC443C, W28, W44 and 3C391 - and two Herbig-Haro objects, HH7 and HH54, using Spitzer's Infrared Spectrograph (IRS). The physical conditions within the observed areas are inferred from spectroscopic data obtained from IRS and from SWS and LWS onboard ISO, together with photometric data from Spitzer's Infrared Array Camera (IRAC). Adopting a power-law distribution for the gas temperature in the observed region, the H2 S(0) to S(7) spectral line maps obtained with IRS were used to constrain the gas density, yielding estimated n(H2) in the range 2-4*10^3 cm^-3. The excitation of H2 S(9) to S(12) and high-J CO pure rotational lines, however, require environments several times denser. The inconsistency among the best-fit densities estimated from different species can be explained by density fluctuations within the observed regions. The best-fit power-law index b is smaller than the value 3.8 predicted for a paraboloidal C-type bow shock, suggesting that the shock front has a "flatter" shape than that of a paraboloid. The best-fit parameters for SNRs and Herbig-Haro objects do not differ significantly between the two classes of sources, except that for the SNRs the ortho-to-para ratio (OPR) of hot gas (T> 1000 K) is close to the LTE value 3, while for HH7 and HH54 even the hottest gas exhibits an OPR smaller than 3. Finally, we mapped the physical parameters within the regions observed with IRS and found that the mid-lying H2 emissions - S(3) to S(5) - tend to trace the hot component of the gas, while the intensities of S(6) and S(7) are more sensitive to the density of the gas compared to S(3) to S(5).

References in corpus (4)

• Spitzer observations of HH54 and HH7-11: mapping the H2 ortho-to-para ratio in shocked molecular gas
• Spitzer spectral line mapping of supernova remnants: I. Basic data and principal component analysis
• Mapping warm molecular hydrogen with Spitzer's Infrared Array Camera (IRAC)
• Molecular line emission in HH54: a coherent view from near to far infrared

Cited by in corpus (17)

• Herschel/PACS Spectroscopic Survey of Protostars in Orion: The Origin of Far-Infrared CO Emission
• Collisional excitation of far-infrared line emissions from warm interstellar carbon monoxide (CO)
• Efficient ortho-para conversion of H2 on interstellar grain surfaces
• Quantum Calculation of Inelastic CO Collisions with H: I. rotational quenching of low-lying rotational levels
• Probing MHD Shocks with high-J CO observations: W28F
• APEX observations of supernova remnants - I. Non-stationary MHD-shocks in W44
• The water abundance behind interstellar shocks: results from $Herschel$/PACS and $Spitzer$/IRS observations of H${}_2$O, CO, and H${}_2$
• Hot Molecular Gas in the Circumnuclear Disk
• AKARI Near-infrared Spectral Observations of Shocked H2 Gas of the Supernova Remnant IC 443
• JOYS: The [D/H] abundance derived from protostellar outflows across the Galactic disk measured with JWST
• Rovibrational (de-)excitation of H${}_2$ by He revisited
• Submillimeter observations of molecular gas interacting with the supernova remnant W28
• Proper Motions and Shock Wave Dynamics in the HH 7-11 Stellar Jet
• C-type shock modelling -- the effect of new H${}_2$-H collisional rate coefficients
• Supernova Shocks in Molecular Clouds: Shocks Driven into Dense Cores in IC 443 and 3C 391
• Analysis of the first infrared spectrum of quasi-bound H2 line emission in Herbig-Haro 7
• A Spectroscopic Study of Supernova Remnants with the Infrared Space Observatory