The Centaurus a Ultrahigh-Energy Cosmic-Ray Excess and the Local Extragalactic Magnetic Field

Yüksel, Hasan; Stanev, T.; Kistler, Matthew D.; Kronberg, P. P.

doi:10.1088/0004-637x/758/1/16

Cited by 26 publications

(22 citation statements)

References 66 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition, the missing anisotropy of UHE CR events challenges this interpretation. Possible caveats to this result could be large ensemble-fluctuations of intrinsic source properties that have been omitted in this study (but could easily be included) and/or strong deflections in inter-galactic magnetic fields [53,54] (see further below).…”

Section: Discussionmentioning

confidence: 99%

“…Typically, neutron-rich isotopes β-decay to a stable or long-lived nucleus with the same mass number. In most cases there is only one stable nucleus per mass number below 56 Fe with the exception of the pairs 54 Cr/ 54 Fe, 46 Ca/ 46 Ti, 40 Ar/ 40 Ca and 36 S/ 36 Ar. We follow here the approach of Puget, Stecker and Bredekamp (PSB) [25] and consider only a single nucleus per mass number A in the decay chain of primary iron 56 Fe.…”

Section: Propagation Of Cosmic Ray Nucleimentioning

confidence: 99%

See 1 more Smart Citation

Ensemble fluctuations of the flux and nuclear composition of ultrahigh energy cosmic ray nuclei

2013

View full text Add to dashboard Cite

The flux and nuclear composition of ultra-high energy cosmic rays depend on the cosmic distribution of their sources. Data from cosmic ray observatories are yet inconclusive about their exact location or distribution, but provide a measure for the average local density of these emitters. Due to the discreteness of the emitters the flux and nuclear composition is expected to show ensemble fluctuations on top of the statistical variations, i.e. "cosmic variance". This effect is strongest for the most energetic cosmic rays due to the limited propagation distance in the cosmic radiation background and is hence a local phenomenon. For the statistical analysis of cosmic ray emission models it is important to quantify the possible level of this variance. In this paper we present a completely analytic method that describes the variation of the flux and nuclear composition with respect to the local source density. We highlight that proposed future space-based observatories with exposures of O(10 6 km 2 sr yr) will attain sensitivity to observe these spectral fluctuations in the cosmic ray energy spectrum at Earth relative to the overall power-law fit.PACS numbers: 96.50.S-, 98.70.Sa, 13.85.Tp

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Propagation Of Cosmic Ray Nucleimentioning

confidence: 99%

Ensemble fluctuations of the flux and nuclear composition of ultrahigh energy cosmic ray nuclei

2013

View full text Add to dashboard Cite

show abstract

“…A known point source of UHECRs can be used to probe the intergalactic magnetic fields in the vicinity of the source. For Cen A, this kind of study was done in Yuksel et al (2012). Here, we provide the order estimate from our results for comparison.…”

Section: Discussionmentioning

confidence: 99%

Centaurus a as a Point Source of Ultrahigh Energy Cosmic Rays

Kim

2013

ApJ

View full text Add to dashboard Cite

We probe the possibility that Centaurus A (Cen A) is a point source of ultrahigh energy cosmic rays (UHECRs) observed by Pierre Auger Observatory (PAO), through the statistical analysis of the arrival direction distribution. For this purpose, we set up the Cen A dominance model for the UHECR sources, in which Cen A contributes the fraction f C of the whole UHECR with energy above 5.5 × 10 19 eV and the isotropic background contributes the remaining 1 − f C fraction. The effect of the intergalactic magnetic fields on the bending of the trajectory of Cen A originated UHECRs is parameterized by the Gaussian smearing angle θ s . For the statistical analysis, we adopted the correlational angular distance distribution (CADD) for the reduction of the arrival direction distribution and the Kuiper test to compare the observed and the expected CADDs. We identify the excess of UHECRs in the Cen A direction and fit the CADD of the observed PAO data by varying two parameters f C and θ s of the Cen A dominance model. The best-fit parameter values are f C ≈ 0.1 (the corresponding Cen A fraction observed at PAO is f C,PAO ≈ 0.15, that is, about 10 out of 69 UHECRs) and θ s = 5• with the maximum likelihood L max = 0.29. This result supports the existence of a point source smeared by the intergalactic magnetic fields in the direction of Cen A. If Cen A is actually the source responsible for the observed excess of UHECRs, the rms deflection angle of the excess UHECRs implies the order of 10 nG intergalactic magnetic field in the vicinity of Cen A.

show abstract

“…However, despite this, we do note that the incorporation of random components of the GMF and/or appropriate EGMF would likely wash out the distribution obtained in the present simulation, making it look more like the observed event distribution (e.g. Yüksel et al 2012). …”

Section: Effects Of Gmf On the Arrival Directions Of Uhecrs And Its Imentioning

confidence: 58%

On the Excess of Ultra-High Energy Cosmic Rays in the Direction of Centaurus A

Liu

Wang

et al. 2012

ApJ

View full text Add to dashboard Cite

A posteriori anisotropy study of ultra-high energy cosmic rays (UHECRs) with the Pierre Auger Observatory (PAO) has shown evidence of excess of cosmic ray particles above 55 EeV within 18 • of the direction of the radio galaxy Centaurus A. However, the origin of the excess remains elusive. We simulate the propagation of different species of particles coming from the direction of Centaurus A in the Galactic magnetic fields, and find that only particles of nuclear charge Z 10 can avoid being deflected outside of the 18 • window of Centaurus A. On the other hand, considering the increasingly heavy composition of UHECRs at the highest energies measured by PAO, a plausible scenario for cosmic rays from the direction of Centaurus A can be found if they consist of intermediate-mass nuclei. The chemical composition of cosmic rays can be further constrained by lower-energy cosmic rays of the same rigidity. We find that cosmic ray acceleration in the lobes of Centaurus A is not favored, while acceleration in the stellar winds that are rich in intermediate-mass nuclei, could meet the requirement. This suggests that the observed excess may originate from cosmic ray accelerators induced by stellar explosions in the star-forming regions of Centaurus A and/or the Centaurus cluster located behind Centaurus A.

show abstract

The Centaurus a Ultrahigh-Energy Cosmic-Ray Excess and the Local Extragalactic Magnetic Field

Cited by 26 publications

References 66 publications

Ensemble fluctuations of the flux and nuclear composition of ultrahigh energy cosmic ray nuclei

Ensemble fluctuations of the flux and nuclear composition of ultrahigh energy cosmic ray nuclei

Centaurus a as a Point Source of Ultrahigh Energy Cosmic Rays

On the Excess of Ultra-High Energy Cosmic Rays in the Direction of Centaurus A

Contact Info

Product

Resources

About