Calibrating Column Density Tracers With Gamma-Ray Observations of the Ρ Ophiuchi Molecular Cloud

Abrahams, Ryan; Teachey, Alex

doi:10.3847/1538-4357/834/1/91

Cited by 4 publications

(6 citation statements)

References 48 publications

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“…We note that all of the new extended sources are found at low latitudes (     | | b 4 20 ), 69 implying potential Galactic origin. We found the sources were generally associated with either SNRs or SFRs, the two exceptions being the ρ Oph Cloud, which was originally discovered by COSB at γ-ray energies (Mayer-Hasselwander et al 1980) and was previously found as an extended object in γ-rays (Lande et al 2012;Abrahams et al 2017), and the Crab Nebula, which did not pass the extension criteria threshold in Ackermann et al (2017c). Figure 3 shows the detected extension and extension upper limits for all the sources investigated in this analysis.…”

Section: Extension Catalogmentioning

confidence: 73%

The Search for Spatial Extension in High-latitude Sources Detected by the Fermi Large Area Telescope

Ackermann¹,

Ajello²,

Baldini³

et al. 2018

ApJS

187

162

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We present a search for spatial extension in high-latitude (>  | | b 5) sources in recent Fermi point source catalogs. The result is the Fermi High-Latitude Extended Sources Catalog, which provides source extensions (or upper limits thereof) and likelihood profiles for a suite of tested source morphologies. We find 24extended sources, 19 of which were not previously characterized as extended. These include sources that are potentially associated with supernova remnants and star-forming regions. We also found extended γ-ray emission in the vicinity of the CenA radio lobes and-at GeV energies for the first time-spatially coincident with the radio emission of the SNR CTA 1, as well as from the Crab Nebula. We also searched for halos around active galactic nuclei, which are predicted from electromagnetic cascades induced by the e + e − pairs that are deflected in intergalactic magnetic fields. These pairs are produced when γ-rays interact with background radiation fields. We do not find evidence for extension in individual sources or in stacked source samples. This enables us to place limits on the flux of the extended source components, which are then used to constrain the intergalactic magnetic field to be stronger than 3×10 −16 G for a coherence length λ10 kpc, even when conservative assumptions on the source duty cycle are made. This improves previous limits by several orders of magnitude.

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Section: Extension Catalogmentioning

confidence: 73%

The Search for Spatial Extension in High-latitude Sources Detected by the Fermi Large Area Telescope

Ackermann¹,

Ajello²,

Baldini³

et al. 2018

ApJS

187

162

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“…For example, since we expect that on scales larger than a protoplanetary disk, dust and gas should generally be well coupled and the dust-to-gas ratio should not vary much within gas of the same metallicity, it is natural to use observations of the dust to constrain the gas column density. Dust extinction measurements provide the cleanest measure of the column density (Lombardi & Alves, 2001;Kainulainen & Tan, 2013;Abrahams et al, 2017) but require one to have deep near IR and/or mid IR maps of the background stellar population in order to detect the extinction. If these are unavailable, the technique cannot be used.…”

Section: Probability Density Functionsmentioning

confidence: 99%

Synthetic observations of star formation and the interstellar medium

Haworth

Glover

Koepferl

et al. 2018

New Astronomy Reviews

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Synthetic observations are playing an increasingly important role across astrophysics, both for interpreting real observations and also for making meaningful predictions from models. In this review, we provide an overview of methods and tools used for generating, manipulating and analysing synthetic observations and their application to problems involving star formation and the interstellar medium. We also discuss some possible directions for future research using synthetic observations.

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“…The total uncertainty including the statistical and systematic uncertainty is calculated with their root sum square, 11 and is shown as a red band in Fig. 5.…”

Section: A Results Of the Baseline Model And The Systematic Uncertaimentioning

confidence: 99%

“…The interaction of CRs with the interstellar gas will produce γ-ray photons. On one hand, these γ rays can be a useful tracer of total gas column density [7][8][9][10][11][12][13][14], since the γ rays are transparent to the interstellar medium (ISM) and also independent of the chemical and thermodynamic state. On the other hand, γ-ray observation provides a unique way to probe the Galactic CRs outside the solar system.…”

Section: Introductionmentioning

confidence: 99%

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Probing local cosmic rays using Fermi-LAT observations of a mid-latitude region in the third Galactic quadrant

et al. 2019

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The γ-ray observation of interstellar gas provides a unique way to probe the cosmic rays (CRs) outside the solar system. In this work, we use an updated version of Fermi-LAT data and recent multi-wavelength tracers of interstellar gas to re-analyze a mid-latitude region in the third Galactic quadrant and estimate the local CR proton spectrum. Two γ-ray production cross section models for pp interaction, the commonly used one from Kamae et al. (2006) and the up-to-date one from Kafexhiu et al. (2014), are adopted separately in the analysis. Both of them can well fit the emissivity and the derived proton spectra roughly resemble the direct measurements from AMS-02 and Voyager 1, but rather different spectral parameters are indicated. A break at 4 ± 1 GeV c −1 is shown if the cross section model by Kamae et al. (2006) is adopted. The resulting spectrum is 20% larger than the AMS-02 observation above 15 GeV and consistent with the de-modulated spectrum within 2%. The proton spectrum based on the cross section model of Kafexhiu et al. (2014) is about 1.4 − 1.8 times that of AMS-02 at 2 − 100 GeV, however the difference decreases to 20% below 10 GeV with respect to the de-modulated spectrum. A spectral break at 20±11 GeV c −1 is required in this model. An extrapolation down to 300 MeV is performed to compare with the observation of Voyager 1, and we find a deviation of 2.5σ for both the models. In general, an approximately consistent CR spectrum can be obtained using γ-ray observation nowadays, but we still need a better γ-ray production cross section model to derive the parameters accurately.

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Calibrating Column Density Tracers With Gamma-Ray Observations of the Ρ Ophiuchi Molecular Cloud

Cited by 4 publications

References 48 publications

The Search for Spatial Extension in High-latitude Sources Detected by the Fermi Large Area Telescope

The Search for Spatial Extension in High-latitude Sources Detected by the Fermi Large Area Telescope

Synthetic observations of star formation and the interstellar medium

Probing local cosmic rays using Fermi-LAT observations of a mid-latitude region in the third Galactic quadrant

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