A large-scale survey of X-ray filaments in the Galactic Centre

Johnson, Seth; Dong, Hui; Wang, Q. Daniel

doi:10.1111/j.1365-2966.2009.15362.x

Cited by 31 publications

(64 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…According to Johnson et al (2009), the soft (<10 keV) X-ray spectrum of the filament has a photon index of G S ∼ 1 for a power-law model (albeit with a large uncertainty) and the 2-10 keV luminosity is ∼2×10…”

Section: Discussionmentioning

confidence: 99%

“…In particular, NGP 59 is located at the southern end of the small (11″×6 5) X-ray filament, G0.007-0.014 (Johnson et al 2009;Ponti et al 2015b). According to Johnson et al (2009), the soft (<10 keV) X-ray spectrum of the filament has a photon index of G S ∼ 1 for a power-law model (albeit with a large uncertainty) and the 2-10 keV luminosity is ∼2×10…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

NuSTAR HARD X-RAY SURVEY OF THE GALACTIC CENTER REGION. II. X-RAY POINT SOURCES

Hong

Mori

Hailey

et al. 2016

ApJ

View full text Add to dashboard Cite

We present the first survey results of hard X-ray point sources in the Galactic Center (GC) region by NuSTAR. We have discovered 70 hard (3-79 keV) X-ray point sources in a 0.6 deg 2 region around SgrA * with a total exposure of 1.7 Ms, and 7 sources in the SgrB2 field with 300 ks. We identify clear Chandra counterparts for 58 NuSTAR sources and assign candidate counterparts for the remaining 19. The NuSTAR survey reaches X-ray luminosities of ∼4× and ∼8×10 32 erg s -1 at the GC (8 kpc) in the 3-10 and 10-40 keV bands, respectively. The source list includes three persistent luminous X-ray binaries (XBs) and the likely run-away pulsar called the Cannonball. New source-detection significance maps reveal a cluster of hard (>10 keV) X-ray sources near the SgrA diffuse complex with no clear soft X-ray counterparts. The severe extinction observed in the Chandra spectra indicates that all the NuSTAR sources are in the central bulge or are of extragalactic origin. Spectral analysis of relatively bright NuSTAR sources suggests that magnetic cataclysmic variables constitute a large fraction (>40%-60%). Both spectral analysis and logN-logS distributions of the NuSTAR sources indicate that the X-ray spectra of the NuSTAR sources should have kT>20 keV on average for a single temperature thermal plasma model or an average photon index of Γ=1.5-2 for a power-law model. These findings suggest that the GC X-ray source population may contain a larger fraction of XBs with high plasma temperatures than the field population.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

NuSTAR HARD X-RAY SURVEY OF THE GALACTIC CENTER REGION. II. X-RAY POINT SOURCES

Hong

Mori

Hailey

et al. 2016

ApJ

View full text Add to dashboard Cite

show abstract

“…Similarly, the electrons injected by the population of PWNe detected with Chandra in the inner 30 pc (Muno et al 2008;Johnson et al 2009) could potentially provide a large γ-ray luminosity. But given the large infrared (IR) and optical photon field energy densities in the GC region, the measured energy spectra should show pronounced Klein−Nishina suppression effects in the TeV γ-ray range, which is inconsistent with the hard spectrum without any cut−off reported in paper II in the central 0.45…”

Section: Morphologymentioning

confidence: 99%

“…The thickness of the filament also constrains the magnetic field to be larger than 20 µG (Ė/10 35 erg/s) 1/2 (Wang et al 2002). No significant cooling is visible along the filament (Johnson et al 2009). …”

Section: Nature Of the Sourcementioning

confidence: 99%

Characterising the VHE diffuse emission in the central 200 parsecs of our Galaxy with H.E.S.S.

Abdalla

Abramowski

Aharonian

et al. 2018

A&A

View full text Add to dashboard Cite

The diffuse very high−energy (VHE, > 100 GeV) γ-ray emission observed in the central 200 pc of the Milky Way by H.E.S.S. was found to follow the dense matter distribution in the Central Molecular Zone (CMZ) up to a longitudinal distance of about 130 pc to the Galactic Centre (GC), where the flux rapidly decreases. This was initially interpreted as the result of a burst−like injection of energetic particles 10 4 years ago, but a recent more sensitive H.E.S.S. analysis revealed that the cosmic−ray (CR) density profile drops with the distance to the centre, making data compatible with a steady cosmic PeVatron at the GC. In this paper, we extend this analysis to obtain for the first time a detailed characterisation of the correlation with matter and to search for additional features and individual γ-ray sources in the inner 200 pc. Taking advantage of 250 hours of H.E.S.S. data and improved analysis techniques we perform a detailed morphology study of the diffuse VHE emission observed from the GC ridge and reconstruct its total spectrum. To test the various contributions to the total γ-ray emission, we use an iterative 2D maximum likelihood approach that allows us to build a phenomenological model of the emission by summing a number of different spatial components. We show that the emission correlated with dense matter covers the full CMZ and that its flux is about half the total diffuse emission flux. We also detect some emission at higher latitude likely produced by hadronic collisions of CRs in less dense regions of the GC interstellar medium. We detect an additional emission component centred on the GC and extending over about 15 pc that is consistent with the existence of a strong CR density gradient and confirms the presence of a CR accelerator at the very centre of our Galaxy. We show that the spectrum of the full ridge diffuse emission is compatible with the one previously derived from the central regions, suggesting that a single population of particles fills the entire CMZ. Finally, we report the discovery of a VHE γ-ray source near the GC radio arc and argue that it is produced by the pulsar wind nebula candidate G0.13−0.11.

show abstract

“…Chandra observations detected a filamentary X-ray structure (G0.13−0.11) sandwiched between nonthermal radio filaments of the Arc and the 6.4 keV line emission from the extended molecular cloud G0.11−0.11 molecular gas (Yusef-Zadeh et al 2002). This filament has a photon index Γ = 1.4-1.5 (Wang et al 2002a;Johnson et al 2009). The nature of this filament, which has neither 6.4 keV line nor radio continuum counterparts, suggests that the nonthermal X-ray emission is consistent with a synchrotron emission from electrons with TeV energies.…”

Section: Time Variability Of Fe I Kα Line Emissionmentioning

confidence: 99%

Interacting Cosmic Rays With Molecular Clouds: A Bremsstrahlung Origin of Diffuse High-Energy Emission From the Inner 2°×1° of the Galactic Center

Yusef‐Zadeh

Hewitt

Wardle

et al. 2012

ApJ

133

191

View full text Add to dashboard Cite

The high-energy activity in the inner few degrees of the Galactic center is traced by diffuse radio, X-ray, and γ -ray emission. The physical relationship between different components of diffuse gas emitting at multiple wavelengths is a focus of this work. We first present radio continuum observations using the Green Bank Telescope and model the nonthermal spectrum in terms of a broken power-law distribution of ∼GeV electrons emitting synchrotron radiation. We show that the emission detected by Fermi is primarily due to nonthermal bremsstrahlung produced by the population of synchrotron emitting electrons in the GeV energy range interacting with neutral gas. The extrapolation of the electron population measured from radio data to low and high energies can also explain the origin of Fe i 6.4 keV line and diffuse TeV emission, as observed with Suzaku, XMM-Newton, Chandra, and the H.E.S.S. observatories. The inferred physical quantities from modeling multiwavelength emission in the context of bremsstrahlung emission from the inner ∼300×120 pc of the Galactic center are constrained to have the cosmic-ray ionization rate ∼1-10 × 10 −15 s −1 , molecular gas heating rate elevating the gas temperature to 75-200 K, fractional ionization of molecular gas 10 −6 -10 −5 , large-scale magnetic field 10-20 μG, the density of diffuse and dense molecular gas ∼100 and ∼10 3 cm −3 over 300 pc and 50 pc path lengths, and the variability of Fe i Kα 6.4 keV line emission on yearly timescales. Important implications of our study are that GeV electrons emitting in radio can explain the GeV γ -rays detected by Fermi and that the cosmic-ray irradiation model, like the model of the X-ray irradiation triggered by past activity of Sgr A * , can also explain the origin of the variable 6.4 keV emission from Galactic center molecular clouds.

show abstract

A large-scale survey of X-ray filaments in the Galactic Centre

Cited by 31 publications

References 31 publications

NuSTAR HARD X-RAY SURVEY OF THE GALACTIC CENTER REGION. II. X-RAY POINT SOURCES

NuSTAR HARD X-RAY SURVEY OF THE GALACTIC CENTER REGION. II. X-RAY POINT SOURCES

Characterising the VHE diffuse emission in the central 200 parsecs of our Galaxy with H.E.S.S.

Interacting Cosmic Rays With Molecular Clouds: A Bremsstrahlung Origin of Diffuse High-Energy Emission From the Inner 2°×1° of the Galactic Center

Contact Info

Product

Resources

About