Tentative evidence of spatially extended GeV emission from SS433/W50

We have analyzed ten years of the Fermi Large Area Telescope data toward the SS433/W50 region. With the latest source catalog and diffuse background models, the γ-ray excess from SS433/W50 is detected with a significance of ~6σ in the photon energy range of 500 MeV–10 GeV. Our analysis indicates that an extended flat disk morphology is preferred over a point-source description, suggesting that the GeV emission region is much larger than that of the TeV emission detected by the High Altitude Water Cherenkov (HAWC) telescope. The size of the GeV emission is instead consistent with the extent of the radio nebula W50, a supernova remnant being distorted by the jets, so we suggest that the GeV emission may originate from this supernova remnant. The spectral result of the GeV emission is also consistent with a supernova remnant origin. Furthermore, we derive the GeV flux upper limits on the TeV emission region, which put moderate constraints on the leptonic models to explain the multiwavelength data.

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

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2461 ◽

2019 ◽

Vol 489 (3) ◽

pp. 4300-4310 ◽

Cited By ~ 5

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.

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Observation of Supernova Remnant IC 443 with the Fermi Large Area Telescope

10.2172/1057406 ◽

2012 ◽

Author(s):

A Abdo

Keyword(s):

Supernova Remnant ◽

Large Area

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Fermi-LAT and WMAP observations of the supernova remnant Puppis A

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313009617 ◽

2013 ◽

Vol 9 (S296) ◽

pp. 295-299

Author(s):

Marie-Hélène Grondin ◽

John W. Hewitt ◽

Marianne Lemoine-Goumard ◽

Thierry Reposeur ◽

Keyword(s):

Supernova Remnants ◽

Supernova Remnant ◽

Gamma Ray ◽

High Energy ◽

Radio Spectrum ◽

Wilkinson Microwave Anisotropy Probe ◽

Large Area ◽

X Ray ◽

Inverse Compton Scattering ◽

Γ Ray

AbstractThe supernova remnant (SNR) Puppis A (aka G260.4-3.4) is a middle-aged supernova remnant, which displays increasing X-ray surface brightness from West to East corresponding to an increasing density of the ambient interstellar medium at the Eastern and Northern shell. The dense IR photon field and the high ambient density around the remnant make it an ideal case to study in γ-rays. Gamma-ray studies based on three years of observations with the Large Area Telescope (LAT) aboard Fermi have revealed the high energy gamma-ray emission from SNR Puppis A. The γ-ray emission from the remnant is spatially extended, and nicely matches the radio and X-ray morphologies. Its γ-ray spectrum is well described by a simple power law with an index of ~2.1, and it is among the faintest supernova remnants yet detected at GeV energies. To constrain the relativistic electron population, seven years of Wilkinson Microwave Anisotropy Probe (WMAP) data were also analyzed, and enabled to extend the radio spectrum up to 93 GHz. The results obtained in the radio and γ-ray domains are described in detail, as well as the possible origins of the high energy γ-ray emission (Bremsstrahlung, Inverse Compton scattering by electrons or decay of neutral pions produced by proton interactions).

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η Carinae with Fermi-LAT: two full orbits and the third periastron

Astronomy and Astrophysics ◽

10.1051/0004-6361/202140451 ◽

2021 ◽

Vol 654 ◽

pp. A44

Author(s):

G. Martí-Devesa ◽

O. Reimer

Keyword(s):

Binary Systems ◽

High Energy ◽

Particle Accelerators ◽

Large Area ◽

Large Dataset ◽

Energy Emission ◽

Collision Region ◽

Upper Limits ◽

High Energy Emission ◽

Energy Components

Context. Colliding-wind binaries are massive stellar systems featuring strong, interacting winds. These binaries may be actual particle accelerators, making them variable γ-ray sources due to changes in the wind collision region along the orbit. However, only two of these massive stellar binary systems have been identified as high-energy sources. The first and archetypical system of this class is η Carinae, a bright γ-ray source with orbital variability peaking around its periastron passage. Aims. The origin of the high-energy emission in η Carinae is still unclear, with both lepto-hadronic and hadronic scenarios being under discussion. Moreover, the γ-ray emission seemed to differ between the two periastrons previously observed with the Fermi-Large Area Telescope. Continuing observations might provide highly valuable information for understanding the emission mechanisms in this system. Methods. We have used almost 12 yr of data from the Fermi-Large Area Telescope. We studied both low- and high-energy components, searching for differences and similarities between both orbits, and we made use of this large dataset to search for emission from nearby colliding-wind binaries. Results. We show how the energy component above 10 GeV of η Carinae peaks months before the 2014 periastron, while the 2020 periastron is the brightest one to date. Additionally, upper limits are provided for the high-energy emission in other particle-accelerating colliding-wind systems. Conclusions. Current γ-ray observations of η Carinae strongly suggest that the wind collision region of this system is perturbed from orbit to orbit, affecting particle transport within the shock.

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An Instrument to Study the Diffuse EUV Astronomical Background

International Astronomical Union Colloquium ◽

10.1017/s0252921100036630 ◽

1996 ◽

Vol 152 ◽

pp. 611-616 ◽

Cited By ~ 1

Author(s):

S. Bowyer ◽

J. Edelstein ◽

M. Lampton ◽

L. Morales ◽

J. Perez Mercader ◽

...

Keyword(s):

Dark Matter ◽

Interstellar Medium ◽

Extreme Ultraviolet ◽

Unique Line ◽

Upper Limits ◽

Diffuse Background ◽

Source Mechanisms ◽

New Type

The extreme ultraviolet (EUV) diffuse background is the most poorly known of any of the diffuse astronomical backgrounds. Only upper limits to this flux exist, obtained with spectrometers with very crude (from ≈ 15 to 30 Å) resolution; these limits are generally one to two orders of magnitude larger than the expected sources of cosmic flux. A variety of source mechanisms have been postulated to radiate in this bandpass; the most discussed is the hot phase of the interstellar medium. A speculative possibility is that hot dark matter in the form of massive, radiatively unstable neutrinos in our Galaxy will produce a unique line in this bandpass. We describe an instrument employing a new type of spectrometer which will provide ~5 Å resolution and unprecedented sensitivity for diffuse EUV radiation. The instrument will be carried aboard the newly developed Spanish Minisat satellite.

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Search for γ-ray emission from superluminous supernovae with the Fermi-LAT

Astronomy and Astrophysics ◽

10.1051/0004-6361/201730741 ◽

2018 ◽

Vol 611 ◽

pp. A45 ◽

Cited By ~ 13

Author(s):

N. Renault-Tinacci ◽

K. Kotera ◽

A. Neronov ◽

S. Ando

Keyword(s):

Neutron Stars ◽

Confidence Level ◽

Compact Object ◽

Photon Spectrum ◽

Systematic Search ◽

Large Area ◽

Rotation Periods ◽

Upper Limit ◽

Upper Limits ◽

Γ Ray

We present the first individual and stacking systematic search for γ-ray emission in the GeV band in the directions of 45 superluminous supernovae (SLSNe) with the Fermi Large Area Telescope (LAT). No excess of γ-rays from the SLSN positions was found. We report γ-ray luminosity upper limits and discuss the implication of these results on the origin of SLSNe and, in particular, the scenario of central compact object-aided SNe. From the stacking search, we derived an upper limit at 95% confidence level to the γ-ray luminosity (above 600 MeV) Lγ < 9.1 × 1041 erg s−1 for an assumed E−2 photon spectrum for our full SLSN sample. We conclude that the rate of the neutron stars born with millisecond rotation periods P ≲ 2 ms and B ~ 1012−13 G must be lower than the rate of the observed SLSNe. The luminosity limits obtained on individual sources are also constraining: in particular, SN2013fc, CSS140222, SN2010kd, and PTF12dam can only be born with millisecond periods if B ≲ 1013 G.

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Locating the gamma-ray emission region in the brightest Fermi-LAT flat-spectrum radio quasars

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3483 ◽

2020 ◽

Vol 500 (4) ◽

pp. 5297-5321

Author(s):

Atreya Acharyya ◽

Paula M Chadwick ◽

Anthony M Brown

Keyword(s):

Time Scales ◽

Gamma Ray ◽

High Energy ◽

Emission Region ◽

Large Area ◽

Line Region ◽

Spectrum Radio ◽

Show Evidence ◽

Very High Energy ◽

Gamma Ray Emission

ABSTRACT We present a temporal and spectral analysis of the gamma-ray flux from nine of the brightest flat-spectrum radio quasars (FSRQs) detected with the Fermi Large Area Telescope during its first 8 yr of operation, with the aim of constraining the location of the emission region. Using the increased photon statistics obtained from the two brightest flares of each source, we find evidence of sub-hour variability from B2 1520+31, PKS 1502+106, and PKS 1424−41, with the remaining sources showing variability on time-scales of a few hours. These indicate gamma-ray emission from extremely compact regions in the jet, potentially compatible with emission from within the broad-line region (BLR). The flare spectra show evidence of a spectral cut-off in 7 of the 18 flares studied, further supporting the argument for BLR emission in these sources. An investigation into the energy dependence of cooling time-scales finds evidence for both BLR origin and emission from within the molecular torus (MT). However, Monte Carlo simulations show that the very high energy (Eγ ≥ 20 GeV) emission from all sources except 3C 279, 3C 454.3, and 4C 21.35 is incompatible with a BLR origin. The combined findings of all the approaches used suggest that the gamma-ray emission in the brightest FSRQs originates in multiple compact emission regions throughout the jet, within both the BLR and the MT.

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Diversity of γ-ray and radio variability of bright blazars and implications for γ-ray emission location

Publications of the Astronomical Society of Japan ◽

10.1093/pasj/psaa029 ◽

2020 ◽

Vol 72 (3) ◽

Author(s):

Hai-Ming Zhang ◽

Zhen-Jie Wang ◽

Jin Zhang ◽

Ting-Feng Yi ◽

Liang Chen ◽

...

Keyword(s):

Time Lag ◽

Light Curves ◽

Emission Region ◽

Large Area ◽

Central Engine ◽

Variation Patterns ◽

Multi Wavelength ◽

Γ Ray ◽

Fast Spike

Abstract Violent multi-wavelength variabilities are observed in γ-ray-selected blazars. We present an analysis of long-term light curves for eight bright blazars to explore the co-variation pattern in the γ-ray and radio bands. We extract their γ-ray light curves and spectra with data observed by the Fermi Large Area Telescope (LAT) since 2008. We find diverse co-variation patterns between the γ-ray and radio (at 43 GHz) fluxes in these sources. The γ-ray and radio fluxes of 3C 454.3 and PKS 1633+382 are correlated without any time lag, suggesting that they are from the same radiation region. Similar correlation is also observed in 3C 273 and PKS 1222+216, but the radio flux lags behind the γ-ray flux by approximately ∼160 d and ∼290 d, respectively. This likely suggests that their γ-ray emission regions are located the upstream of their radio cores at 43 GHz. The γ-ray and radio fluxes of the other four blazars are not correlated, implying that the γ-ray and radio emission may be from different regions in their jets. The γ-ray light curves of the eight blazars can be decomposed into some components with long-timescale variability and some fast spike flares. We propose that they may be attributed to the central engine activity and the magnetic reconnection process or turbulence in the local emission region, respectively.

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A LOFAR search for steep-spectrum pulsars in supernova remnants and pulsar wind nebulae

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833922 ◽

2019 ◽

Vol 623 ◽

pp. A90 ◽

Cited By ~ 1

Author(s):

S. M. Straal ◽

J. van Leeuwen

Keyword(s):

Black Hole ◽

Supernova Remnants ◽

Supernova Remnant ◽

Point Sources ◽

Pulsar Wind Nebulae ◽

Upper Limits ◽

Formation History ◽

Propagation Effects ◽

Pulsar Wind ◽

Rule Out

Pinpointing a pulsar in its parent supernova remnant (SNR) or resulting pulsar wind nebula (PWN) is key to understanding its formation history and the pulsar wind mechanism, yet only about half the SNRs and PWNe appear associated with a pulsar. Our aim was to find the pulsars in a sample of eight known and new SNRs and PWNe. Using the LOFAR radio telescope at 150 MHz, each source was observed for 3 h. We covered the entire remnants where needed, by employing many tied-array beams to tile out even the largest objects. For objects with a confirmed point source or PWN we constrained our search to those lines of sight. We identified a promising radio pulsar candidate towards PWN G141.2+5.0. The candidate, PSR J0337+61, has a period of 94 ms and a DM of 226 pc cm−3. We re-observed the source twice with increased sensitivities of 30% and 50%, but did not re-detect it. It thus remains unconfirmed. For our other sources we obtain very stringent upper limits of 0.8 − 3.1 mJy at 150 MHz. Generally, we can rule out that the pulsars travelled out of the remnant. From these strict limits we conclude our non-detections towards point sources and PWNe are the result of beaming and propagation effects. Some of the remaining SNRs should host a black hole rather than a neutron star.

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