Issue |
A&A
Volume 511, February 2010
|
|
---|---|---|
Article Number | A34 | |
Number of page(s) | 6 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361/200913312 | |
Published online | 02 March 2010 |
Nonthermal and thermal emission from the supernova remnant RX J1713.7-3946
E. G. Berezhko1 - H. J. Völk2
1 - Yu.G. Shafer Institute of Cosmophysical Research and Aeronomy,
31 Lenin Ave., 677980 Yakutsk, Russia
2 -
Max Planck Institut für Kernphysik,
Postfach 103980, 69029 Heidelberg, Germany
Received 17 September 2009 / Accepted 19 November 2009
Abstract
Aims. A nonlinear kinetic theory of cosmic ray (CR)
acceleration in supernova remnants (SNRs) is employed to investigate
the properties of SNR RX J1713.7-3946.
Methods. Observations of the nonthermal radio and X-ray emission spectra, as well as the HESS measurements of the very high energy -ray emission,
are used to constrain the astronomical and CR acceleration parameters
of the system. It is argued that RX J1713.7-3946 is a core
collapse supernova (SN) of type II/Ib with a massive progenitor, and it
has an age of
1600 yr and is at a distance of
1 kpc.
It is also assumed that the CR injection/acceleration takes place
uniformly across the shock surface for this kind of core collapse SNR.
Results. The theory gives a consistent description for all the
existing observational data, including the nondetection of thermal
X-rays and the spatial correlation of the X-ray and -ray emission
in the remnant. Specifically, it is shown that an efficient production
of nuclear CRs, leading to strong shock modification and a strong
downstream magnetic field
G can reproduce in detail the observed synchrotron emission from radio to X-ray frequencies, together with the
-ray spectral characteristics as observed by the HESS telescopes.
Conclusions. The calculations are consistent with RX J1713.7-3946 being an efficient source of nuclear CRs.
Key words: ISM: cosmic rays - acceleration of particles - shock waves - ISM: individual objects: RX J1713.7-3946 - radiation mechanisms: non-thermal - gamma rays: ISM
1 Introduction
The shell-type supernova remnant (SNR), RX J1713-3946, located in the Galactic plane was discovered in X-rays with ROSAT (Pfeffermann & Aschenbach 1996). Subsequent studies of this SNR with the ASCA satellite by Koyama et al. (1997) and Slane et al. (1999), and later with XMM by Cassam-Chenaï et al. (2004), have not positively identified any thermal X-ray emission so they tentatively concluded that the observable X-ray emission is entirely nonthermal.
The radio emission, on the other, hand is quite weak. Only part of the remnant
shell could be detected in radio synchrotron emission up to now, with a poorly
known spectral form (Lazendic et al. 2004). For the spatially integrated radio flux,
Aharonian et al. (2006) estimate about twice the value found by Lazendic et al. (2004). Most
recently, Acero et al. (2009) have derived a total flux value of
at 1.4 GHz, still about two times higher than
estimated by Aharonian et al. (2006). As far as the estimate of the magnetic field
strength is concerned, this higher estimate of the radio synchrotron flux
increases the magnetic field estimate (see below).
RX J1713-3946 was also detected in very high-energy (VHE: >100 GeV) -rays with
the CANGAROO (Enomoto et al. 2002; Muraishi et al. 2000) and HESS telescopes
(Aharonian et al. 2007,2004,2006). Especially the latter, very detailed observations
show a clear shell structure at TeV energies that correlates well with the
ASCA contours.
In a first theoretical paper on this source (Berezhko & Völk 2006), we investigated the
acceleration of CR electrons and protons in detail, using nonlinear kinetic
theory (Berezhko et al. 1996; Berezhko & Völk 2000). Observations of the nonthermal radio and X-ray
emission spectra, as well as the HESS measurements of the very high-energy
-ray emission, were used to constrain the astronomical and the particle
acceleration parameters of the system. Under the assumption that RX J1713.7-3946 is the
remnant of a core collapse supernova (SN) of type II/Ib with a massive
progenitor, the theory indeed gives a consistent description for the existing
data on the nonthermal emission. The VHE data from HESS were specifically
shown to be best explained as hadronic
-ray emission, where the magnetic field
amplification strongly depresses the inverse Compton and Bremsstrahlung
fluxes. Subsequently (Berezhko & Völk 2008), we analyzed the spatial correlation between
the synchrotron and the VHE emission, which has been used before as an argument
for a leptonic origin of the VHE emission (Katz & Waxman 2008; Plaga 2008). It has been
argued that correlated density and magnetic field strength variations lead
rather naturally to a spatial correlation of the hadronic VHE emission with the
synchrotron emission. Similar arguments have been brought forward by
Tanaka et al. (2008). Also, the recent broad-band X-ray synchrotron measurements
(Uchiyama et al. 2007; Takahashi et al. 2008) with the Suzaku instrument were compared to the theoretical
synchrotron spectra and were found to be quite consistent with a hadronic
model. A purely leptonic model, on the other hand (e.g. Porter et al. 2006),
where magnetic field amplification is not expected, was shown to be
inconsistent with these observations. Acero et al. (2009) have also considered a
leptonic origin of the
-ray emission as a viable possibility. This has to be
compared with the results of the present paper.
These theoretical considerations assumed that only over part of the shock
surface injection of suprathermal nuclear ions occurs effectively, because the
magnetic field is essentially parallel to the shock surface over other
parts. In fairly regular SNRs like those of type Ia explosions into a
presumably uniform circumstellar environment, this is a significant effect, as
in the case of SN 1006. For a blast wave propagating into the highly turbulent
shell of a stellar wind bubble from a massive progenitor star, on the other
hand, the magnetic flux tubes in the shell are presumably so slender and
irregular that energetic particles can cross diffusively into regions where
suprathermal injection is depressed, yet acceleration is possible. As a result,
shock modification by the pressure gradient of the accelerating particles
becomes possible everywhere on the shock surface. This reasoning follows the
discussion in Berezhko et al. (2009) with the conclusion that SNRs propagating into wind
bubbles should have their forward shock modified everywhere. Technically, this
implies that the SNR becomes spherically symmetric and the correction factor
(Völk et al. 2003) on the spherically symmetric solution reaches
unity. The ubiquitous shock modification also has implications for the thermal
emission, because the thermal gas, heated within the precursor due to the MHD
wave damping and later in the subshock, only reaches lower temperatures than in
the case of an unmodified shock.
In contrast to the previous studies (Berezhko & Völk 2006,2008) of RX J1713.7-3946, we therefore
adopt here the approximation of spherically symmetric CR
injection/acceleration with
(see
also Zirakashvili 2009). It is demonstrated that in this approximation a
consistent solution can also be found. In addition, a rough estimate of the
thermal X-ray emission from this object is given. Even though the error
in this estimate might be quite large, the nominal result is consistent with
the present non-detection of thermal X-rays (e.g. Acero et al. 2009).
Finally, the observed correlation of the X-ray and the VHE
-ray emission is
discussed in a generalized form.
2 Results
![]() |
Figure 1:
a) Shock radius |
Open with DEXTER |
As in the previous studies (Berezhko & Völk 2006,2008), a source distance
of d=1 kpc is adopted here. For the present angular source size of
about 60 arcmin, this implies an SNR radius
pc.
For the SNR age the value
yr is used,
consistent with the hypothesis of Wang et al. (1997) that RX J1713-3946 is the
remnant of the AD393 ``guest star''.
It had been argued (Berezhko & Völk 2006) that the existing data are only consistent with
RX J1713.7-3946 being a core collapse SN of type II/Ib. Those progenitor stars of core
collapse SNe that emit intense winds are massive main-sequence stars with
initial masses
.
During their evolution in a
surrounding uniform ISM of gas number density
,
the
wind termination shock creates a hot bubble of shocked wind material,
surrounded by a turbulent shell of shocked ISM behind an outer forward shock
that communicates the internal overpressure to the environment.
The gas number density distribution
is
assumed to have the form
![]() |
(1) |
corresponding to a very low-density bubble (




Under these conditions an SN explosion energy
erg and an ejecta mass
lead to a good fit
for the observed SNR properties. To determine the explosion energy directly
from the data, the value of the shock speed
would have been
needed. However, this quantity is not known. The ejecta energy
is still about
.
Together with the
kinetic energy of the shocked gas
,
this makes up about half of the total
energy
(see Fig. 1).
The spectral fit, also for the -ray data, can be achieved with the values
of the proton injection rate and
G for the downstream magnetic field strength. Such
values of
are significantly higher than for typical ambient
magnetic fields, also for the considered bubble wall in the dense
environment. (The gas density at the shock is still a factor
100 lower
than in that environment, which implies a strongly decompressed field upstream
of the SNR shock compared to the value in the ambient medium.) The high
-value must be attributed to field amplification at the shock
front because of the strong wave production by the acceleration of CRs far into
the nonlinear regime (Lucek & Bell 2000; Bell 2004)
.
It is assumed that also electrons are injected into the acceleration process at
the shock front. Since the details of the electron injection process are poorly
known, the electron injection rate is chosen such that
the electron to proton ratio
(defined as the ratio of
their distribution functions at all rigidities where the protons are already
relativistic and the electrons have not yet been cooled radiatively) is a
constant to be determined from the synchrotron observations. Clearly, from the
point of view of injection/acceleration theory,
,
together with
and
,
must be treated as theoretically not very well-constrained parameters to
be quantitatively determined by comparison with the available synchrotron
and
-ray data. Here,
is the overall shock compression ratio.
In the present case, the following parameter values were obtained by iteration:
,
B0=25
G,
.
The
gas dynamic variables at the present epoch are
,
,
and
km s-1, where
and
denote the subshock compression ratio
and the overall shock velocity, respectively (Fig. 1).
The corresponding solutions of the dynamic equations at each instant of time
yield the CR spectrum and the spatial distributions of CRs and thermal gas,
hence also the expected fluxes of nonthermal emission produced by the
accelerated CRs. The overall broadband spectral energy distribution (SED), expected at the
current evolutionary epoch, is displayed in Fig. 2, together with the
experimental data from ATCA at radio wavelengths, as estimated for the
full remnant by Acero et al. (2009), the X-ray data from ASCA (Aharonian et al. 2006)
and Suzaku (Uchiyama et al. 2007), and the HESS -ray data (Aharonian et al. 2007).
The comparison with our earlier theoretical spectrum (Berezhko & Völk 2008) shows that also a model with full spherical symmetry can successfully describe the spatially integrated nonthermal emission properties of this object.
At energies
TeV the theoretical
-ray spectrum is as hard
as
,
whereas
for
TeV it has a smooth cutoff. It should be noted that
the
-ray cutoff energy
is sensitive to the magnetic field strength
,
since the proton cutoff momentum has a dependence
(Berezhko 1996).
Note that the energy loss time of energetic protons due to their hadronic
collisions with the background nuclei is so long
108 yr, that it does
not play any role in determining
.
The theoretical results presented here are fully consistent with a dominantly
hadronic origin of the observed TeV -rays . At the present epoch, the SNR has
already converted
35% of
into accelerated nuclei.
2.1 Estimate of the thermal X-ray emission
![]() |
Figure 2:
Spatially integrated, overall nonthermal spectral energy distribution
of RX J1713.7-3946. The solid curve at energies above 107 eV corresponds to
|
Open with DEXTER |
As for the case of RX J0852.0-4622 (Berezhko et al. 2009) in addition the expected flux of thermal X-rays is estimated here. This is only possible in a very approximate way, even if we disregard the ejecta emission with the argument that the ejected mass in the present phase is small compared to the swept-up mass. The reason is the explosion into the wind bubble, creating a rather different thermodynamical structure from that of a classical Sedov solution for an SN explosion into a uniform medium, until now exclusively considered in the literature. Nevertheless the remnant of RX J1713.7-3946 in the stellar wind shell is approaching a roughly self-similar evolutionary phase, modified by strong particle acceleration relative to a purely gas dynamic evolution. Other estimates of the thermal emission from RX J1713.7-3946 have been made by Katz & Waxman (2008) and Drury et al. (2008), effectively assuming an explosion into a uniform medium.
The approximation adopted here is the following. The present bubble case is
compared with an SNR in a uniform medium in the classical Sedov phase without
any CR acceleration, making four assumptions: (i) the total hydrodynamic
explosion energy is the same in both cases; (ii) the shock velocity is the
same; (iii) the present gas density upstream of the shock is the same; and (iv)
the two objects are at the same distance of 1 kpc. Then the results of
Hamilton et al. (1983) for the thermal X-ray flux from a classical Sedov SNR are used,
employing the emission measure of the bubble remnant instead of that of the
classical Sedov remnant with the same four parameters above. The thermal X-ray
emission at keV-energies is dominated by lines, so it cannot be approximated by
some simple analytical formula. We use the results of numerical calculations
performed by Hamilton et al. (1983) with some corrections. These mean that the X-ray
emissivity of the remnant is reduced by the ratio
of the emission measure
for our
bubble solution to the emission measure for the classical Sedov solution
,
which corresponds to a uniform ambient gas density
(Berezhko et al. 2009).
Also the relation
![]() |
(2) |
is used, with




Using the differential thermal X-ray model spectra
photons/(keV cm2 s) from Hamilton et al. (1983) (for
,
see their Fig. 2) for their
erg cm-6 taking into account the scaling
with our model numbers
erg cm-6, multiplying it by the factor
,
as required, where
arcmin for the angular size of the classical Sedov remnant corresponding
to RX J1713.7-3946, and multiplying it also by the factor
,
results
in a thermal spectral energy density
eV cm-2 s-1 for
keV.
This result has not yet taken into account that the actual postshock gas
temperature
is lower by a factor
0.41 than the
temperature
used in the above estimate. As discussed in
Berezhko et al. (2009), this roughly corresponds to a reduced parameter value
erg cm-6 and thus to a reduction in the
thermal flux at 1 keV to
eV cm-2 s-1.
These numbers must be compared with the observed nonthermal X-ray energy flux
eV cm-2 s-1 at 1 keV (see
Fig. 2). Therefore, at 1 keV, the thermal energy flux is smaller
than the nonthermal flux by a factor of about 2. This does not contradict the
nondetection of thermal X-rays from RX J1713.7-3946.
2.2 Spatial correlation of the nonthermal X-ray fluxes with the
-ray fluxes
Acero et al. (2009) find a positive spatial nonlinear correlation







2.2.1 Correlation of the radial profiles
In terms of the spherically symmetric model, discussed here, the
correlation between X-ray and -ray fluxes means that the projected radial
profiles
and
of these emissions
as functions of projected radial distance
have similar shapes. At first
sight this contradicts this model: as can be seen from Figs. 3 and 4,
the calculated profiles are significantly different. Both profiles have a sharp
peak just behind the shock front, but the X-ray profile is by a factor of about
3 thinner than the
-ray profile. However, when smoothed with the point spread
function of width
,
corresponding to the
HESS angular resolution, these profiles become very similar.
Acero et al. (2009) compared XMM measurements of the X-ray emission smoothed with a
point spread function of width
.
It can therefore be
concluded that the similarity of the X-ray and the
-ray radial profiles is a
trivial consequence of smoothing two differently sharp peaks by a point
spread function whose width is considerably greater than the widths of either
one of the emission peaks.
The experimentally observed correlation according to Fig. 9 of Acero et al. (2009)
is fairly close to the relation
for all the brighter
SNR regions. Some deviation from this relation is observed for six of the
outer and dimmer regions, for which
.
This
peculiarity can also be explained within the present model. The reason is that
protons with an energy of about 100 TeV occupy a region, that is noticeably
larger than the shock size
,
because of their high diffusive
mobility. The 10 TeV
-ray emission these protons produce has an even
larger radial extension since the gas density strongly increases with radial
distance. Such an effect is absent for the electrons of the same energy which
produce the nonthermal keV-emission. As a result of their strong energy losses,
they occupy a region thinner than
around the shock
front. Therefore, as can be clearly seen from Figs. 3 and 4, the ratio
is expected to increase as a function of radial
distance for
,
as the data of Acero et al. (2009) are
interpreted here.
2.2.2 Correlation of azimuthal variations
![]() |
Figure 3:
The X-ray emissivities for the energy
|
Open with DEXTER |
![]() |
Figure 4:
The |
Open with DEXTER |
The measured X-ray and -ray emissions also undergo rather closely correlated
azimuthal variations across the remnant. Such an effect cannot be described
within the present model model, because it is spherically symmetric. One can
nevertheless attempt to interpret the correlated behavior of the fluxes
and
in different azimuthal sectors of the
remnant. It is natural to assume that this variation in the remnant properties
stems from variations in the ambient gas density
.
According to the
model proposed here, the SNR's present evolutionary phase is intermediate
between the sweep-up and a quasi-Sedov phase. Since the ejecta kinetic energy,
together with the kinetic energy of the swept-up gas, contains about half of the
explosion energy, the SN shock can be approximately treated as a piston-driven
shock rather than a pressure-driven shock in the Sedov phase. The speed of such
a shock depends only weakly upon the upstream gas density. Therefore
can be approximated by a constant across the whole remnant.
The local hadronic -ray emission then varies like
,
where the local CR energy content
in each angular sector is assumed to be the same everywhere,
because the overall CR energy content
has already reached the saturation level and therefore cannot undergo
significant variations. In addition, the highest energy CRs in the SNR
have the highest diffusive mobility so that they tend to be distributed roughly
uniformly across the remnant.
As is clear from Fig. 2, the synchrotron spectrum at high energies
eV is already considerably influenced
by synchrotron losses of the emitting electrons. Since the energy of these
electrons is fairly rapidly and completely transformed into synchrotron
emission, the flux
is
determined by the available energy flux
into the shock, an
essential part of which is transformed at the shock front into the energy flux
of high-energy CRs. High-energy electrons therefore accumulate a fraction
of this flux. This flux hardly depends on the value of the
interior magnetic field in all those SNR regions where the field is
sufficiently high,
G. In this case the relation
is expected for the brightest part of remnant.
This is indeed observed (Acero et al. 2009). Since the energy density of the
amplified magnetic field
is phenomenologically known to be
proportional to
,
with
(Völk et al. 2005), it is expected to be proportional to the local upstream gas
density
.
The magnetic field strength is therefore lower than the
average value
140
G within those parts of the remnant where the
gas density is lower than the average value. Synchrotron losses become much
smaller in these regions and therefore the expected synchrotron X-ray flux is
approximately
.
For the dim part of the
remnant, in which X-ray and
-ray emission is considerably lower than on average,
one then obtains
.
This is approximately
consistent with the observational result.
3 Summary
The assumption that CR injection/acceleration takes place uniformly across the whole SN shock surface is consistent with the existing data. The swept-up mass is so low in this case that, in a rough approximation, the estimated flux of thermal X-rays at 1 keV is lower than the nonthermal flux, consistent with the nondetection of thermal X-ray emission until now.It is concluded that the present observational knowledge of SNR RX J1713.7-3946 can be
interpreted by a source that ultimately converts more than 35% of the
mechanical explosion energy into nuclear CRs. Also, the observed high-energy
-ray emission of SNR RX J1713.7-3946 turns out to primarily be of hadronic origin.
The authors thank V. S. Ptuskin and V. N. Zirakashvili for discussions of the thermal emission properties. This work was supported in part by the Russian Foundation for Basic Research (grants 06-02-96008, 07-02-0221). E.G.B. acknowledges the hospitality of the Max-Planck-Institut für Kernphysik, where part of this work was carried out.
References
- Abbott, D. C. 1982, ApJ, 263, 723 [NASA ADS] [CrossRef] [Google Scholar]
- Acero, F., Ballet, J., Decourchelle, A., et al. 2009, A&A, 505, 157 [NASA ADS] [CrossRef] [EDP Sciences] [Google Scholar]
- Aharonian, F. A., Akhperjanian, A., Aye, K.-M., et al. (HESS Collaboration) 2004, Nature, 432, 75 [Google Scholar]
- Aharonian, F. A., Akhperjanian, A., Bazer-Bachi, A. R., et al. (HESS Collaboration) 2006, A&A, 449, 223 [Google Scholar]
- Aharonian, F. A., Akhperjanian, A., Bazer-Bachi, A. R., et al. (HESS Collaboration) 2007, A&A, 464, 235 [Google Scholar]
- Ballet, J. 2006, Adv. Space Res., 37, 1902 [NASA ADS] [CrossRef] [Google Scholar]
- Bell, A. R. 2004, MNRAS, 353, 550 [Google Scholar]
- Berezhko, E. G. 1996, Astropart. Phys., 5, 367 [NASA ADS] [CrossRef] [Google Scholar]
- Berezhko, E. G. 2005, Adv. Space Res., 35, 1031 [NASA ADS] [CrossRef] [Google Scholar]
- Berezhko, E. G. 2008, Adv. Space Res., 41, 429 [Google Scholar]
- Berezhko, E. G., & Völk, H. J. 2000, A&A, 357, 183 [Google Scholar]
- Berezhko, E. G., & Völk, H. J. 2006, A&A, 451,981 [NASA ADS] [CrossRef] [EDP Sciences] [Google Scholar]
- Berezhko, E. G., & Völk, H. J. 2008, A&A, 492,695 [NASA ADS] [CrossRef] [EDP Sciences] [Google Scholar]
- Berezhko, E. G., Elshin, V. K., & Ksenofontov, L. T. 1996, JETPh, 82, 1 [Google Scholar]
- Berezhko, E. G., Pühlhofer, G., & Völk, H. J. 2009, A&A, 505, 641 [NASA ADS] [CrossRef] [EDP Sciences] [Google Scholar]
- Cassam-Chenaï, G., Decourshelle, A., Ballet, J., et al. 2004, A&A, 427, 199 [NASA ADS] [CrossRef] [EDP Sciences] [Google Scholar]
- Drury, L.O'C., Aharonian, F. A., Malyshev, D., & Gabici, S. 2008, A&A, 496, 1 [Google Scholar]
- Enomoto, R., Tanimori, T., Naito, T., et al. 2002, Nature, 416, 823 [NASA ADS] [CrossRef] [PubMed] [Google Scholar]
- Enomoto, R., Watanabe, S., Tanimori, T., et al. 2006, ApJ, 652, 1268 [NASA ADS] [CrossRef] [Google Scholar]
- Fukui, Y., Moriguchi, Y., Tamura, K., et al. 2003, PASJ, 55, L61 [NASA ADS] [Google Scholar]
- Hamilton, A. J. S., Sarazin, C. L., & Chevalier, R. A. 1983, ApJS, 41, 115 [NASA ADS] [CrossRef] [Google Scholar]
- Hiraga, J. S., Uchiyama, Y., Takahashi, T., et al. 2005, A&A, 431, 953 [NASA ADS] [CrossRef] [EDP Sciences] [Google Scholar]
- Katz, B., & Waxman, E. 2008, JCAP, 01, 1 [Google Scholar]
- Koyama, K., Kinagasa K., Matsuzaki, K., et al. 1997, PASJ, 49, L7 [NASA ADS] [Google Scholar]
- Lazendic, J. S., Slane, P. O., Gaensler, B. M., et al. 2004, ApJ, 602, 271 [NASA ADS] [CrossRef] [Google Scholar]
- Lucek, S. G., & Bell, A. R. 2000, MNRAS, 314, 65 [NASA ADS] [CrossRef] [Google Scholar]
- Moriguchi, Y., Tamura, T., Tawara, Y., et al. 2005, ApJ, 641, 947 [NASA ADS] [CrossRef] [Google Scholar]
- Muraishi, H., Tanimori, T., & Yanagita, S. 2000, A&A, 354, L57 [NASA ADS] [Google Scholar]
- Pfeffermann, E., & Aschenbach, B. 1996, in Röntgenstrahlung from the Universe, ed. H. U. Zimmermann, J. Trümper, & H. Yorke, MPE Rep., 263, Garching, 267 [Google Scholar]
- Plaga, R. 2008, New Astron., 13, 73 [NASA ADS] [CrossRef] [Google Scholar]
- Porter, T. A., Moskalenko, I. V., & Strong, A. W. 2006, ApJ, 648, L29 [NASA ADS] [CrossRef] [Google Scholar]
- Slane, P., Gaensler, B. M., Dame, T., et al. 1999, ApJ, 357, SL99 [NASA ADS] [CrossRef] [Google Scholar]
- Takahashi, T., Tanaka, T., Uchiyama, Y., et al. 2008, PASJ, 60, S131 [NASA ADS] [CrossRef] [Google Scholar]
- Tanaka, T., Uchiyama, Y., Aharonian, F. A., et al. 2008, ApJ, 685, 988 [NASA ADS] [CrossRef] [Google Scholar]
- Uchiyama, Y., Aharonian, F. A., Tanaka, T., et al. 2007, Nature, 449, 576 [NASA ADS] [CrossRef] [PubMed] [Google Scholar]
- Völk, H. J., Berezhko, E. G., & Ksenofontov, L. T. 2003, A&A, 409, 563 [NASA ADS] [CrossRef] [EDP Sciences] [Google Scholar]
- Völk, H. J., Berezhko, E. G., & Ksenofontov, L. T. 2005, A&A, 433, 229 [NASA ADS] [CrossRef] [EDP Sciences] [Google Scholar]
- Wang, Z. R., Qu, Q.-Y., & Chen, Y. 1997, A&A, 318, L59 [NASA ADS] [Google Scholar]
- Zirakashvili, V. N. 2009, in High Energy Gamma-Ray Astronomy, ed. F. A. Aharonian, W. Hofmann, & F. M. Rieger, Melville, New York, AIP Conf. Proc., 1085, 129 [Google Scholar]
Footnotes
- ... 2004)
- For direct observational evidence regarding magnetic field amplification in RX J1713.7-3946, see Berezhko & Völk (2006); Ballet (2006); Völk et al. (2005).
All Figures
![]() |
Figure 1:
a) Shock radius |
Open with DEXTER | |
In the text |
![]() |
Figure 2:
Spatially integrated, overall nonthermal spectral energy distribution
of RX J1713.7-3946. The solid curve at energies above 107 eV corresponds to
|
Open with DEXTER | |
In the text |
![]() |
Figure 3:
The X-ray emissivities for the energy
|
Open with DEXTER | |
In the text |
![]() |
Figure 4:
The |
Open with DEXTER | |
In the text |
Copyright ESO 2010
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.