The hypothesis that there exists an excess of showers from the Galactic plane on the level 1 to 2% at energies just above 10 to the 16th power eV is explored. The excess shower from the Galactic plane seems to be very similar in properties to excess showers from the point sources/flat spectrum, deficit of low energy muons. Those facts suggest that the excess from the Galactic plane are probably due to summing up of the contribution from individual point sources. That in turn suggest that those sources are rather numerous

Dzikowski, T.

Gawin, J.

Grochalska, B.

Korejwo, J.

Wdowczyk, J.

English

NASA Technical Reports Server

238
OG 2.6-?
SEARCH FOR UI_RA HIGH E_RGY _- RAYS FRO_
VARIOUS SOURCES.
T.Dzikowski, J.Gawin, B.Grochalska, J.Korejwo
and J.Wdowczyk.
Institute of Nuclear Studies and
University of L6d_, Cosmic Ray Laboratory
90-950 L6d_ I, box 447, Poland
I. Introduction.
Recent discoveries of the high energy cosmic ray point
sources, /Dzikowski et al., 1980, 1981, gamorski and Stamm
f1983a, Lloyd-Evans et al., 1983, Protheroe et al., 1984/
interpreted as due to ultra high energy_- rays, called our
attention to the early works on the diffuse ultra high
energy _-rays /Firkowski et al., 1961, Suga et al., 1963/.
One of the main puzzles in the investigations of the point
sources is the fact, stated by the Kiel group /Samorski and
Stamm, 1983b/ and to some extent confirmed by us /Dzikowski
et al., 1983/, that the excess showers are not so muon poor
as they should be in the case of their photon origin.
That conclusion has also • been in a sense, confirmed by .
recent reports about detection of a signal from Cyg X-3, in
the underground muon experiments /see for instance Bartelt
et al., 1984/. It should be also reminded that in the above
mentioned early works on the diffuse photon showers /Gawin
et al., 1965/ it has been found that the muon content in
those showers is clearly hi_er than that expected for
photon initiated showers /Wdowczyk, 1965/.
II. Contribution of the point sources to the diffuse flux
th_ excess showers.
It has been pointed out by Wdowczyk and Wolfendale/1983/
that cortain number of the point sources can in principle
8 OG 2.6-7 
SEARCH FOR UDl'RA HIGH ENERGY 0' - RAYS FROM 
I US CES. 
T.Dzikowski, J.Gawin, B. rochalska, J.Korejwo 
 J.W owczyk. 
stit te  uclear t dies  
niversity of L6dz, Cosmic Ray Laboratory 
- 0 z 1,  , l nd 
 t duction. 
Recent discoveries of the high energy cosmic ray pOint 
sources, / zikowski et l., 1980, 1981, Sa orski and Stam  
19838., Lloyd-Evans et al., 1983, Protheroe et l., 1984/ 
interpreted as due to ultra high energy 0- rays, called our 
attention to the early orks on the diffuse ltra high 
energy o-rays /Firkowski et al., 1961, Suga et al., 1963/. 
One of the ain puzzles in the investigations of the point 
sources is the t t, stated by the iel group / a orski and 
ta m, 83b/ a  t  s e tent nfir ed  s / zikowski 
et al., 1983/, that the excess sho ers are not so uon poor 
as they should be in the case ot their photon origin. 
That conclusion has also been in a sense, confirmed by 
recent reports about detection of a signal from Cyg X-3, in 
t e nderground uon periments / e r i st nce artelt 
t l., 984/. t ould e l  r inded t at i  t  ove 
entioned early orks on the dif~use photon showers / awin 
t l., 965/ t as een f und at t e uon ontent  
those showers is clearly hi~ler than that expected for 
hoton i itiated owers / doWGzyk, 965/. 
I. ontribution f t e point sources t  t e iffuse l x 
t e exce s s owers. 
It as een ointed ut by '~vdowczyk and olfendale/1983/ 
t at certain number of the oint sources can i  rinciple 
https://ntrs.nasa.gov/search.jsp?R=19850025656 2020-03-20T17:52:26+00:00Z
239
oG 2.
explain anisotropies of cosmic rays around 7© 16 eV. Another
question which arrises here is if the showers from the
point sources could be related to the muon poor showers.
:: E_=S_EV E_--O._Cv " The first important observation
here is that shown in figure I
so so taken from our earlier paper
_ 3o_.4 o,F. _-J LoFF so fig_ure shows the m,_on co;ztent
I ;_/ "- _ I L_, " in the excess showers from the
m 20_ 20
." general direction of the Crab
,o ,o Nebula. As it can be seen the
excess showers are rel_tively
":: much poor when we consider the$-5: {-II _)18 2-3 6-7
..:: •
HUM_ER OF MUOHS IN.THE DETECTOR lov) elderly m_lOiqS 9 whereas they
Fteure,'_° Comparison of the muon content *n the appear to be rather nOl_nal in
showems fPo_ the C_ab,dlre_ion vlth that :Ln the
no,-,.._.,o,e_.. ; respect to the muons of hipster
energies. That effect, very puzzlin_ by itself may explain
why the muon poor showers have been found when low ener_7
much detectors were used but not for the hijh energy muons.
i()@ ' '", '' '_,' '"_ The second importcnt ooint _" _. .u S
INT{6R/_LSLOPE__ • "1,,.) ._.F_,-.-)- :_.a
Id" -T )-i,
_.,., . the energ_ spectrum of the much
: " ' poor showers is shown for all
10Iz I.C_:__ _ existinB dat_ /including recent
observations of the hadron less
1(}1_ showers by Nikolski at al <]98_-/i \
_:tr)EN-S_ The main characteristic of thei
L
" 10,4_, ..,, .... , , " spectrum is the fact that simi-
10Is:.. 1014 lOl_Eir_W,. larly as in the case of the
excess showers from the point
_'ig 2. _tegral energy
spectrum of the much soklroes it appears to be verypoom ex_ensive aim
showers, flat, much flatter then in the
case of proton initiated showers.
Those two fact makes the hypothesis about the common
origin of the muon poor and the point sources excess
showers plausible and worthwhile of further investigation.
9 
OG 2.C-7 
lain i tropies o  c ic ra  d 1016 eVe other 
esti n i  .rrises  is i  th  s ers from th  
i t s r es l   r  to th   p r s v;ers. 
T=SGEV ,,-0.5 Gl'V  t im ort:;mt servation 
50 
::: 40 
... 
31: 
o· 
.:Z: 30 • 
III 
.... 
o 
a: 20' 
... 
GI 
,::Ii:' 
::» , 10 
,z 
Off 
--, 
\ .......... 
".:, 
0-2 f~~' 112-17t 0-\ '4-5 p~ 8 
s-~  '-11 ;;.  5.  
UM~iR F UONS I"THE OUECTOR 
50 
40 
30 
20 
10 
rigure1~ o parison f the uon c tent i  the 
showers from ·the Crab ,direction with that 1n the 
normal showers. 
here is that shown in fiGure 1 
ta  fro   rli r 8 er 
/Dzilmwski ct al., 1983/. Tl'hat 
figure s th  'lOl1 CO:Cltc t 
i  th  ess ers from th  
eral ti n  th  r  
ebuln.      th  
ess n ers n  V!ti vcly 
on r hen  (~r th  
10\'1 enert,.;y uons, hereas t ey 
-;:)pear   tber ormal i  
ect t  th  uons  Gh  
ergies. at ct, r  zli G  lf ffi8Y X(llain 
  uon or v,;ers e n d hen o  c rs"Y 
uon t ctors er   t t r th  Gh :i.1ersy :'!luons. 
INT£6RI\L Sl PE_ 
l'-!. 
J CHACAL. TAYA 
10' +'t.ooz 
,t T/EN-SHAN 
1014~ ............. -:t-.......... ~~~ 
10. 10':S 10'6 
E ,(eV) 
Fis 1. Integral ergy 
8pect~ of the muon 
or xtensive ir 
,. ______ s.~ow~rs.~ .. '.: .... 
The second i portcutpoi:':lt is 
the energ~ spectrum of the muon 
or ers  n  ll 
existing data /including recent 
servations f t  ron l  
s ers  ikolski nt l.1984-/ 
The ain c aracteristic of the 
spectru  is the fact t at si i-
larly as in the case of the 
ce s ers   int 
urces  pears   ry 
t, uch tter    
se f r ton iti ted wers. 
hose  ct al<:es  pothe is ut  on 
ri in f  uon oor   oint rces ce s 
'wers l usible  orthwhile f rther estigation. 
240
OG 2.6-7
III. Galactic latitude distribution of the e_ensive air
_howers with different muon content.
In our analysis _vehsve usedthe _'_;_no','. e rs collected in
L6d_ from q975. In figure 3 the Galactic latitude distri-
show_r_
bution of the with N e > 10 6 and different muon content
are shown and compared with the expectations on the
assumption of isotropy. The expected distributions were
obtained using the method develop the Haverah P_ rk
N n E_O6_V group /Astley et al., _981/ and
discussed, in details by Wdo_,_,czyk
' and Wolfendale /_984/. Essence
of the method is that the data
2_ are divided into narrow strips
of declination. For each strip
_ the expected distribution of
the Galactic latitudes is cal-
-_o.-zo.o.2o.4o'6oo_o b' culated assuming isotropy.
_ig 3, Galactic latitude distrlbution
o:th.sho,,o_s,_i_:_o6_d _r_o_ The contributions from the
•_o_oo_t._/ hreshold.... = o.oGev/, different strips are added
Predicted curves calculated as described
i_thet_=.F_s o_v.....b_r o_ according to the weig/its given
_s_ly_e_eot.d. by the experimental data. The
expected curves in figure 9 are nomnalised to the experi-
mental histograms in the interval b = 17.5 °- 77.5 °.
| , |, i ,,ml
It is seen that at low latitu-
N E/_> 560VNe>'lO° des and low much content there .
3o_ exist an excess of sho%_'ers
compared with the expectation.
Similarly as in figure _ the
zo_ excess is most pronounced for
the showers with O- J muons in
,mo the detector, less pronounced
for 2 - _ and practically not
seen for $ - 5 muons.Th_ excess
-_o°-2o- o" _o° _o•6o"_o"_ in the interval b=-_7.5 _ to b=
,_ _. :_o _a_ _s_n_ _ _u_ zo_ _7.5°amounts to 234 showers for
much enerL_ythreshold 5 GeV. O -- 'I muons and "105 for 2 - 5.
240 
OG 2.6-7 
III. G la tic latitude distribution of the extensive air 
§howers with diff rent muon ~ontent. 
In our o.nolysis we 112vG usedt':lo ,sho~' ors collected in 
L6dz from 1975. In fiGure 3 the Golactic latitudo distri-
shower3 > 6 bution of the with Ne 10 and diff rent muon content 
are shown and compared with the expect,,,tions on the 
assumption of isotropy. '1:he expected distributions w re 
obtained using the method develop the H,3verah Park 
N 
300 
200 
Fie; 3. Galcctic latitude distribution 
of the aho"'/era t"!ith lTe>106 :3nd various 
muon content /threshold enerGY O.6GeV/. 
Predicted curves caloulated as described 
in the t,ext. li'lGu::es (51 ves number ot /A' 
nctually detected. 
~roup /Astley et al., 1981/ "and 
discussed,.:i.n detai.ls by Wdowc zyl( 
l),nd Wolfendale /1984/. Essence 
of the method is that the data 
are divi ed into narrovv strips 
of declination. 
the expected 
For e£l,ch strip 
distribution of 
the Galactic latitUdes is cal-
culated assuming isotropy. 
The contributions 
diff rent stri"t)s 
:from the 
are ad ed 
according to the weights civen 
·by the experimental d ta. The 
expected curves in figure 3 are nOTIualised to the experi-
mental histograms in the interval b == 1'7.5°- '77.5°. 
N 
300 
200 
100 
-40· -20' O· 20· 40· 60· 80· b" 
~'ig 4. 1'ho same as in fiG 3 but for 
muon ener,;y threshold 'J GeV. 
It is seen th£l,t at low Intitu-
des and low muon 
exist an ~xcess 
content there 
of showers 
comp1il.red 
S milarly 
with the expectation. 
~s in figure 1 the 
excess is most pronounced for 
the showers with 0 - 1 muons in 
the d tector, less pr nounced 
for 2 - 3 and practically not 
seen for 4 - 5 muons.The excess 
in the interval b=-17.5c to b== 
17.5°amounts to 234 showers for 
o - 1 muons and 105 for 2 - 3. 
241
OG2.6-7
The excess of showers with low latitudes may be noticed
for the high muon energy threshold /5 GeV/ but in that case
is less marked perhaps due
.. :Er)06gev to the fact that it is not
N _ Ne_10o
disapearing with increasing
6oa muon number /figure @/ but does
not seem to exist for showers
400 with Ne < 106 /figure 5/.
IV. Conclusions.
200 It seems that there exist an
excess of showers from the Ga-
lactic plane on the level 1-2 %
-4o'-zo° o- zo"_" 6_o ° b" at energies just above 1016 eV,
F±_5. _h_s_m__s z_ 3 but zor The excess shower from the Ga-
s_an_=sh6,,_rs_=/ 3.I0/.I0_] lactic plane seems to be very
similar in properties to excess showers from the point
sources /flat spectrum, deficit of low energy muons/. Those
facts suggest that the excess from the Galactic plane are
probably due to summing up of the contribution from individ-
ual point sources. That in turn suggest that those sources
are rather numerous.
Reference s_.
Astley et ai.,1981, 17-th Int. C. R. Conf. Paris, 2, 156
Bartelt et aI.,198_, AIG3 HEP PR-8_-80
Dzikowski et ai.,1980, Origin of Cosmic Rays, D.Reidel _327
Dzikowski et ai.,1981, Phil.Trans.R.Soc.Lon., A 301, 641
Dzikowski et ai.,1983, 18-th In_.C.R.Conf. Bangalore,2,W32
Firkowski et aI.,1961, J.Phys.Soc., 17-A-III, F.123
Gawln et al.,d965, 9-th Int. C. R. Conf. London, 2, 639
Lloyd-_vans et al., 1983, Nature, 305, 784
Nikolski et al., 198%, 9-th European C. R. Syrup. Kosice
Protheroe et al.,1984, Astrophys. J., 280, L_7
Samorski and ,_tamm,]983a, AstrophFs. J., 268, L17
" 7_U.•Samors_ i and ,3t_mm, i9_J3b, 16-tn Int. C.R. Conf.Bangalore ,!_1_1
Suga et ai.,196_. 7-th Int. C. R. Co_if. Jaipur, #,9
Wdowczyk, 1965, 9-th Int. C. R. Conf. London, p._91
Wdowczyk et ai.,1983, _{ature, 0_, 609
Wdowczyk et aI.,198_, J. Phys.,G. I__0,1453
41 
G -7 
e ce s f ers ith lo  l tit es ay e oticed 
r t  i h uon ergy t r shold /  e I t i  t at se 
N 
600 
400 
0 
.,' 
E,.) 0.6 GeV 
<10 6 
-40· -ZOo · lO° 40° 60" eo· 6" 
is le'ss arked 
  ct t 
er aps 
  
 
ot 
disapearin~ ith i creasin! 
uon ber / i re 4/ t es 
t n  ist r ers 
with Ne < 106 /figure 5/. 
. onclusions. 
It seems that there exist an 
ce s f ers ro   a-
tic l e   el   
t ergies j st Qbove 16 e e 
ig  T e ame a  :rig :3 t :r  e ce s er ro   a-
smaller showers. 7=/ 3+10 /.105• lactic plane seems to be very 
si ilar i  roperties to excess sho ers fro  t e oint 
s urces /fl t spectru , eficit of lo  energy uons/. hose 
f ts s gest t at t  e cess fro  t  alactic l e r  
r bably e t  s ming  f t. e ntribution fro  i i:.rid-
al oint urces. hat i  t r  ggest t t t se rces 
r  t er erous. 
References. ;:.:;..;;.,;.;;.;..-.;;;.--..;.--
stley et al.,1981, 17-th Int. C. R. Cont. Paris, 2, 156 
artelt t le ,1984, NL EP -84-80 . -
zikowski et al.,1980, rigin of os ic ays, . eidel p.327 
zikowski t 301.,1981, hil. rans.R.Soc.Lon.,  1,  
zikowski et 0.1.,1983, 18-th Int. . .Cont. anGalore,g,a'32 
irkows:d et 0.1.,1961, J. hys.Boc., 17-A-III, F.123 
awin et a1.,1965, 9-th I t. C. . Conf'. London, 2., 639 
Lloyd-l.!."vans ct al., 1983, Nature, .2.9.2, 784 
ikolski t l., 84, -t  uropean . . m . osice 
Prot~:leroe et <3.1.,1984, Astro~)hys. J., g,8.Q, L4-7 
Samorski and 3tamm,1983a, Astrophys. J., 268, L17 
8D.mors~d D.nd ;3tam , 1983b, 18-th I t.  . . c"Or.i1' .Bangalore ,1,131 
uga t l., 6;b -t  t. 0. l1. 0111'. i ur, 4,  
dowczyk, 65, :rt  t. . . oni. ondon, .b' 1 
dowczyk tal.,1 3, Nat re, 305, 609 
dowczyk et al.,1984, J. hys.~ 1£, 1453 


Search for ultra high energy gamma-rays from various sources

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