scholarly journals Radio observations of supernova remnant G1.9+0.3

2019 ◽  
Vol 492 (2) ◽  
pp. 2606-2621 ◽  
Author(s):  
Kieran J Luken ◽  
Miroslav D Filipović ◽  
Nigel I Maxted ◽  
Roland Kothes ◽  
Ray P Norris ◽  
...  
Keyword(s):  
Spectral Index ◽  
Supernova Remnant ◽  
Radio Spectrum ◽  
Northern Region ◽  
Radio Continuum ◽  
Expansion Rate ◽  
Continuum Emission ◽  
Rotation Measure ◽  
Cas A ◽  
Recent Epoch

ABSTRACT We present 1–10 GHz radio continuum flux density, spectral index, polarization, and rotation measure (RM) images of the youngest known Galactic supernova remnant (SNR) G1.9+0.3, using observations from the Australia Telescope Compact Array. We have conducted an expansion study spanning eight epochs between 1984 and 2017, yielding results consistent with previous expansion studies of G1.9+0.3. We find a mean radio continuum expansion rate of (0.78 ± 0.09) per cent yr−1 (or ∼8900 km s−1 at an assumed distance of 8.5 kpc), although the expansion rate varies across the SNR perimetre. In the case of the most recent epoch between 2016 and 2017, we observe faster-than-expected expansion of the northern region. We find a global spectral index for G1.9+0.3 of −0.81 ± 0.02 (76 MHz–10 GHz). Towards the northern region, however, the radio spectrum is observed to steepen significantly (∼−1). Towards the two so-called (east and west) ‘ears’ of G1.9+0.3, we find very different RM values of 400–600 and 100–200 rad m2, respectively. The fractional polarization of the radio continuum emission reaches (19 ± 2) per cent, consistent with other, slightly older, SNRs such as Cas A.

scholarly journals Spectropolarimetry of supernova remnant G296.5 + 10.0

2008 ◽  
Vol 4 (S259) ◽  
pp. 141-144
Author(s):  
Lisa Harvey-Smith ◽  
Bryan M. Gaensler ◽  
C.-Y. Ng ◽  
Anne J. Green
Keyword(s):  
Supernova Remnant ◽  
Galactic Halo ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Smooth Component ◽  
Rotation Measure ◽  
Pixel Image ◽  
Spectral Channels ◽  
The Magnetic Field ◽  
Compact Array

AbstractRadio continuum emission from the supernova remnant G296.5 + 10.0 was observed using the Australia Telescope Compact Array. Using a 104 MHz bandwidth split into 13 × 8 MHz spectral channels, it was possible to produce a pixel-by-pixel image of Rotation Measure (RM) across the entire remnant. A lack of correlation between RM and X-ray surface brightness reveals that the RMs originate from outside the remnant. Using this information, we will characterise the smooth component of the magnetic field within the supernova remnant and attempt to probe the magneto-ionic structure and turbulent scale sizes in the ISM and galactic halo along the line-of-sight.

scholarly journals Discovery of recombining plasma inside the extended gamma-ray supernova remnant HB9

2019 ◽  
Vol 489 (3) ◽  
pp. 4300-4310 ◽  
Author(s):  
A Sezer ◽  
T Ergin ◽  
R Yamazaki ◽  
H Sano ◽  
Y Fukui
Keyword(s):  
Supernova Remnant ◽  
Gamma Ray ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Large Area ◽  
Imaging Spectrometer ◽  
X Ray ◽  
East Region ◽  
X Ray Imaging ◽  
Collisional Ionization

ABSTRACT We present the results from the Suzaku X-ray Imaging Spectrometer observation of the mixed-morphology supernova remnant (SNR) HB9 (G160.9+2.6). We discovered recombining plasma (RP) in the western Suzaku observation region and the spectra here are well described by a model having collisional ionization equilibrium (CIE) and RP components. On the other hand, the X-ray spectra from the eastern Suzaku observation region are best reproduced by the CIE and non-equilibrium ionization model. We discuss possible scenarios to explain the origin of the RP emission based on the observational properties and concluded that the rarefaction scenario is a possible explanation for the existence of RP. In addition, the gamma-ray emission morphology and spectrum within the energy range of 0.2–300 GeV are investigated using 10 yr of data from the Fermi Large Area Telescope (LAT). The gamma-ray morphology of HB9 is best described by the spatial template of radio continuum emission. The spectrum is well fit to a log-parabola function and its detection significance was found to be 25σ. Moreover, a new gamma-ray point source located just outside the south-east region of the SNR’s shell was detected with a significance of 6σ. We also investigated the archival H i and CO data and detected an expanding shell structure in the velocity range of $-10.5$ and $+1.8$ km s−1 that is coinciding with a region of gamma-ray enhancement at the southern rim of the HB9 shell.

scholarly journals On the integrated continuum radio spectrum of supernova remnant W44 (G34.7-0.4): New insights from Planck

2015 ◽  
pp. 29-37 ◽  
Author(s):  
D. Onic
Keyword(s):  
Supernova Remnant ◽  
Dust Emission ◽  
Radio Spectrum ◽  
Radio Continuum ◽  
Continuum Spectrum ◽  
Data Points ◽  
Emission Models ◽  
Continuum Radio ◽  
Emission Detection

In this paper, the integrated continuum radio spectrum of supernova remnant (SNR) W44 was analyzed up to 70 GHz, testing the different emission models that can be responsible for its particular shape. The observations by the Planck space telescope made it possible to analyze the high frequency part of radio emission from SNRs. Although the quality of radio continuum spectrum (a high scatter of data points at same frequencies) prevents us to make definite conclusions, the possibility of spinning dust emission detection towards this remnant is emphasized. In addition, a concave-down feature, due to synchrotron losses, can not be definitely dismissed by the present knowledge of the integrated radio continuum spectrum of this SNR.

Radio Continuum Emission from the Central Stars of M20, and the Detection of a New Supernova Remnant near M20

2000 ◽  
Vol 540 (2) ◽  
pp. 842-850 ◽  
Author(s):  
F. Yusef‐Zadeh ◽  
Mark Shure ◽  
Mark Wardle ◽  
N. Kassim
Keyword(s):  
Supernova Remnant ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Central Stars

scholarly journals Radio properties of the OH megamaser galaxy IRAS 02524+2046

2020 ◽  
Vol 638 ◽  
pp. A78
Author(s):  
Hao Peng ◽  
Zhongzu Wu ◽  
Bo Zhang ◽  
Yongjun Chen ◽  
Xingwu Zheng ◽  
...  
Keyword(s):  
Flux Density ◽  
Spectral Index ◽  
Line Emission ◽  
Far Infrared ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Starburst Galaxy ◽  
Radio Flux ◽  
Vlbi Observations

We present results from VLBI observations of continuum and OH line emission in IRAS 02524+2046 as well as arcsecond-scale radio properties of this galaxy using VLA archive data. We found that there is no significant detection of radio continuum emission from VLBI observations. The arcsecond-scale radio images of this source show no clear extended emission. The total radio flux density at L and C bands are approximately 2.9 mJy and 1.0 mJy, respectively, which indicates a steep radio spectral index between the two bands. A steep spectral index, low brightness temperature, and high q-ratio (i.e., the far-infrared to the radio flux density), which are three critical indicators in the classification of radio activity in the nuclei of galaxies, are all consistent with the classification of this source as a starburst galaxy from its optical spectrum. The high-resolution line profile reveals that we detected both the 1665 MHz and 1667 MHz OH maser lines, which show two and three clear components, respectively. The channel maps show that the maser emission are distributed in a region of ∼210 pc × 90 pc. The detected maser components in different regions indicate similar double spectral features, which might be evidence that this galaxy is at a stage of major merger as seen from the optical morphology.

scholarly journals Protostellar Outflows at the EarliesT Stages (POETS)

2018 ◽  
Vol 619 ◽  
pp. A107 ◽  
Author(s):  
A. Sanna ◽  
L. Moscadelli ◽  
C. Goddi ◽  
V. Krishnan ◽  
F. Massi
Keyword(s):  
Spectral Index ◽  
Young Stars ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Stellar Winds ◽  
Distance Measurements ◽  
Very Large Array ◽  
Star Forming ◽  
Continuum Source ◽  
Star Forming Regions

Context. Weak and compact radio continuum and H2O masers are preferred tracers of the outflow activity nearby very young stars. Aims. We want to image the centimeter free–free continuum emission in the range 1–7 cm (26–4 GHz), which arises in the inner few 1000 au from those young stars also associated with bright H2O masers. We seek to study the radio continuum properties in combination with the H2O maser kinematics to quantify the outflow energetics powered by single young stars. Methods. We made use of the Karl G. Jansky Very Large Array (VLA) in the B configuration at K band and the A configuration at both Ku and C bands in order to image the radio continuum emission toward 25 H2O maser sites with an angular resolution and thermal rms on the order of 0.′′1 and 10 μJy beam−1, respectively. These targets add to our pilot study of 11 maser sites previously presented. The sample of H2O maser sites was selected among those regions that have accurate distance measurements, obtained through maser trigonometric parallaxes, and H2O maser luminosities in excess of 10−6 L⊙. Results. We present high-resolution radio continuum images of 33 sources belonging to 25 star-forming regions. In each region, we detect radio continuum emission within a few 1000 au of the H2O masers’ position; 50% of the radio continuum sources are associated with bolometric luminosities exceeding 5 × 103 L⊙, including W33A and G240.32 + 0.07. We provide a detailed spectral index analysis for each radio continuum source, based on the integrated fluxes at each frequency, and produce spectral index maps with the multifrequency synthesis deconvolution algorithm of CASA. The radio continuum emission traces thermal bremsstrahlung in (proto)stellar winds and jets that have flux densities at 22 GHz below 3 mJy and spectral index values between − 0.1 and 1.3. We prove a strong correlation (r > 0.8) between the radio continuum luminosity (Lrad) and the H2O maser luminosity (LH2O) of (L8 GHz∕mJy kpc2) = 103.8 × (LH2O L⊙)0.74. This power-law relation is similar to that between the radio continuum and bolometric luminosities, which confirms earlier studies. Since H2O masers are excited through shocks driven by (proto)stellar winds and jets, these results provide support to the idea that the radio continuum emission around young stars is dominated by shock ionization, and this holds over several orders of magnitude of stellar luminosites (1–105 L⊙).

scholarly journals Multifrequency radio observations of SNR J0536-6735 (N 59B) with associated pulsar

2012 ◽  
pp. 69-76 ◽  
Author(s):  
L.M. Bozzetto ◽  
M.D. Filipovic ◽  
E.J. Crawford ◽  
Horta de ◽  
M. Stupar
Keyword(s):  
Flux Density ◽  
Supernova Remnant ◽  
Optical Emission ◽  
Shell Morphology ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Density Estimates ◽  
Hii Region ◽  
Pulsar Wind ◽  
Compact Array

We present a study of new Australian Telescope Compact Array (ATCA) observations of supernova remnant, SNR J0536-6735. This remnant appears to follow a shell morphology with a diameter of D=36x29 pc (with 1 pc uncertainty in each direction). There is an embedded HII region on the northern limb of the remnant which made various analysis and measurements (such as flux density, spectral index and polarisation) difficult. The radio-continuum emission followed the same structure as the optical emission, allowing for extent and flux density estimates at 20 cm. We estimate the surface brightness at 1 GHz of 2.55x10?21 Wm?2 Hz?1 sr?1 for the SNR. Also, we detect a distinctive radio-continuum point source which confirms the previous suggestion of this remnant being associated with pulsar wind nebula (PWN). The tail of this remnant is not seen in the radio-continuum images and is only seen in the optical and X-ray images.

scholarly journals The Radio Morphology and Possible Nature of 3C 58

1983 ◽  
Vol 101 ◽  
pp. 341-342
Author(s):  
Ma Er ◽  
Richard G. Strom
Keyword(s):  
Spectral Index ◽  
Radio Telescope ◽  
Intensity Distribution ◽  
Supernova Remnant ◽  
Published Data ◽  
Rotation Measure

Observations have been made of the supernova remnant 3C 58 with the Westerbork Synthesis Radio Telescope at 6 and 49 cm. These measurements provide us with greater resolution and sensitivity than that attained with previously published data. The 49 cm map has been used for comparison with an existing 21 cm one (Wilson and Weiler, 1976) to obtain information on the spectral index, rotation measure and depolarization. The 6 cm map is valuable both for its greater resolution, and for comparing with an observation made with the same instrument eight years previously. The total intensity distribution is shown in Figure 1.

scholarly journals A Nonthermal Superbubble in the Irregular Galaxy IC 10

1988 ◽  
Vol 101 ◽  
pp. 465-467
Author(s):  
Evan D. Skillman
Keyword(s):  
High Resolution ◽  
Spectral Index ◽  
Supernova Remnant ◽  
Radio Continuum ◽  
Irregular Galaxy ◽  
Large Size ◽  
Ic 10

AbstractNew high resolution radio continuum images of the nearby irregular galaxy IC 10 have revealed a large (> 250 pc) nonthermal source. The source is roughly circular with a spectral index of ∼ –0.5, and is most likely a very large supernova remnant. Its large size suggests that it is the result of several supernovae, and may be related to the supershells observed in our own and other galaxies.

scholarly journals Multi-Array λ2 and 6cm Radio Continuum Observations of Sgr A West

1989 ◽  
Vol 136 ◽  
pp. 443-451 ◽  
Author(s):  
F. Yusef-Zadeh ◽  
Mark Morris ◽  
Ron Ekers
Keyword(s):  
Spectral Index ◽  
Stellar Wind ◽  
Galactic Center ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Spectral Indices ◽  
Ionized Gas ◽  
Sgr A ◽  
Index Maps ◽  
East West

Sub-arcsecond (down to 0.1″ × 0.2″) radio continuum observations using the VLA2 in a number of configurations have been carried out in order to investigate the fine-scale morphological details of the ionized gas and the distribution of spectral index along the triskelian-shaped figure of Sgr A West. In addition to finding a number of isolated patches of thermally-emitting gas and an absorbing feature at λ6cm within three arcminutes of the Galactic center, we have observed:1) radio continuum emission from IRS-7, implying that the stellar wind from this supergiant is externally ionized. An improved position for this object was obtained.2) the circular mini-cavity located along the east-west bar of Sgr A West. This feature has a diameter of 2-arcseconds and may have been created by a spherical wind, the source of which is yet to be identified; the seemingly most plausible candidate, IRS-16, is offset by 3″ from the center of the cavity.Spectral index maps having a resolution of 0.7″ × 0.3″ were made from scaled array observations at λ2cm and 6cm. They show that the eastern arm has a spectral index near −0.1, while the northern arm and the bar have positive spectral indices, indicating perhaps a partial opacity effect. The spectral index of IRS-7 is +0.6, consistent with that expected from a completely ionized stellar wind.

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