Relations of radio sources with jets parameters
We considered the sample of galaxies and quasars with jets based on observed data. We obtained the magnetic field strength in these objects using the condition of energy equipartition between the relativistic particles and the magnetic field. We determined values of luminosities in the radio band an...
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| Опубліковано в: : | Кинематика и физика небесных тел |
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| Дата: | 2005 |
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| Мова: | Англійська |
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Головна астрономічна обсерваторія НАН України
2005
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| Цитувати: | Relations of radio sources with jets parameters / A.P. Miroshnichenko // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 86-89. — Бібліогр.: 8 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1860251358443077632 |
|---|---|
| author | Miroshnichenko, A.P. |
| author_facet | Miroshnichenko, A.P. |
| citation_txt | Relations of radio sources with jets parameters / A.P. Miroshnichenko // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 86-89. — Бібліогр.: 8 назв. — англ. |
| collection | DSpace DC |
| container_title | Кинематика и физика небесных тел |
| description | We considered the sample of galaxies and quasars with jets based on observed data. We obtained the magnetic field strength in these objects using the condition of energy equipartition between the relativistic particles and the magnetic field. We determined values of luminosities in the radio band and in optics. The relations of the sample object radio sizes, luminosities, spectral indices, redshift were derived. An estimations of the lifetime for objects with jets were obtained too.
|
| first_indexed | 2025-12-07T18:43:27Z |
| format | Article |
| fulltext |
RELATIONS OF RADIO SOURCES WITH JETS PARAMETERS
A. P. Miroshnichenko
Institute of Radio Astronomy, NAS of Ukraine
4 Chervonopraporna Str., Kharkiv, Ukraine
e-mail: mir@ira.kharkov.ua
We considered the sample of galaxies and quasars with jets based on observed data. We obtained
the magnetic field strength in these objects using the condition of energy equipartition between
the relativistic particles and the magnetic field. We determined values of luminosities in the radio
band and in optics. The relations of the sample object radio sizes, luminosities, spectral indices,
redshift were derived. An estimations of the lifetime for objects with jets were obtained too.
INTRODUCTION
It is known that the physical nature of the nuclei activity of galaxies and quasars is not determined finally. So,
the studies of different physical parameters of these objects are actual and needed for correct theoretical models
of radio sources and for interpretation of observed data. It is important to examine the jet objects.
Jets are the typical features of ∼ 70% of radio galaxies and ∼ 50% of quasars. They contain the relativistic
particles, thermal plasma and magnetic field.
According to modern ideas jets, i.e., collimated beams flowing from active nuclei are responsible for observed
radio structure of objects.
SAMPLE DESCRIPTION
We considered the sample of jet objects from observed data [3, 5–7]. We also used the data according to
the sample objects at the optical and decametric band [1, 2, 8].
Our sample consists of 132 radio sources with jets, including 76 galaxies and 56 quasars. The mean sample
redshift value is 0.066±0.012 for galaxies, and 0.982±0.084 for quasars. On the whole for our sample the mean
redshift value is 0.510 ± 0.063. The mean spectral index has value 〈a〉 = 0.75 ± 0.04 for objects with redshift
z ≤ 〈z〉 and 〈a〉 = 0.64 ± 0.06 for objects with redshift z > 〈z〉.
THE DETERMINATION OF PHYSICAL PARAMETERS OF JET OBJECTS
At accounts of physical parameters of objects we suppose the synchrotron mechanism of generation of optical
and radio radiation of active nuclei. In this paper the flat model of the Universe with parameter q0 = 0.5 and
the Hubble constant H0 = 100 km/s Mpc is used. As jets are well collimated flows, we consider that the losses
of energy of relativistic electrons on adiabatic expansion of a jet are insignificant in relation to losses of their
energy on synchrotron radiation. The jets can be kept from expansion both external pressure, and own magnetic
field.
For definition of a magnetic field strength of radio sources we accept a hypothesis about equipartition of
magnetic field energy and energy of relativistic particles. Under such condition of the magnetic field strength
of a radio source we find from the ratio [4]:
B =
[
48kA(γ, ν)
Sν
rϕ3
]2/7
, (1)
where k = 100 (proton to electron energy ratio); A(γ, ν) is the tabular function; γ is the index of the electron
energy distribution; Sν is the flux density with respect to frequency; r is the jet distance; ϕ is the jet angular
dimension.
The determined values B range from ∼ 10−2 to 10−5 G that corresponds to known data. The mean value
of the magnetic field strength is 〈BG〉 = 1.37 (±0.99) · 10−4 G for galaxies and 〈BG〉 = 1.6 (±1.2) · 10−3 G for
quasars. We estimated values of minimal total energy
c© A. P. Miroshnichenko, 2004
86
Emin = Erel + EB =
7
4
(1 + k)A(γ, ν) r2 Sν
B3/2
(2)
and total luminosities for jet objects by using values of magnetic field strength
Ltot = cπR2B2. (3)
These values are
〈
Emin
〉
G
= 3.77 (±1.65) · 1060 erg, 〈Ltot〉G = 5.68 (±3.23) · 1048 erg/s,
〈
Emin
〉
Q
=
7.14 (±2.45) · 1060 erg, 〈Ltot〉Q = 1.03 (±0.16) · 1049 erg/s for galaxies and quasars, respectively.
We also derived the characteristic size of radio structure (mean value of object radii) 〈R〉G =
2.54 (±0.77) · 1023 cm, 〈R〉Q = 2.07 (±0.34) · 1023 cm for galaxies and quasars, respectively.
We considered that the active nuclei luminosity of jet sources Ltot is near the critical luminosity value
Ledd = 1.2 · 1038 M
M�
, (4)
which corresponds to Eddington limit for given mass. From this ratio we estimated object masses 〈MG〉 =
9.46 (±5.38) · 1043 g, 〈MQ〉 = 1.71 (±0.26) · 1043 g for galaxies and quasars, respectively.
Based on our data we calculated the characteristic time of the synchrotron decay of relativistic electrons in
jet sources:
tB =
(
340B−3
ν
)1/2
, (5)
where tB is in years, B is in Gauss, ν is in MHz. This value is 〈tb〉G = 4.39 (±1.84) · 106 yr for galaxies and
〈tb〉Q = 1.44 (±0.41) · 106 yr for quasars at the centimeter band. For the decametric band these estimates are
increase to one order, that is 〈tB〉G ∼ 5 · 107 yr, 〈tB〉Q ∼ 107 yr.
From the other side, we derived the minimal source age tL as
tL =
Emin
Ltot
, (6)
and it is 〈tL〉G = 7.47 (±2.26) · 1011 s, 〈tL〉Q = 6.09 (±1.01) · 1011 s.
To estimate the velocity of jet propagation we used both the value tL and the source radius:
v =
R
tL
. (7)
For our sample we derived the sublight velocities of jet propagation which indicate the dependence from
redshift:
〈v〉G = 4.98 (±2.14) · 109 cm/s, 〈z〉G = 0.07; 〈v〉Q = 1.99 (±0.71) · 1010 cm/s, 〈z〉Q = 0.98.
Supposing that object luminosity Ltot is due to matter flowing, we obtained the mean rate of matter flowing
dM
dt
for galaxies and quasars by the relation:
Ltot =
1
2
dM
dt
v2. (8)
Then, the values
〈
dM
dt
〉
are the next:
〈
dM
dt
〉
G
= 7.30 (±2.14) · 1029 g/s and
〈
dM
dt
〉
Q
= 3.38 (±0.66) · 1029 g/s
for galaxies and quasars. So, we obtained the additional estimate of the jet object age:
tM =
M
dM
dt
(9)
with values 〈tM 〉G = 6.63 (±5.27) · 1014 s and 〈tM 〉Q = 2.60 (±0.96) · 1015 s for galaxies and quasars.
We also calculated the ratios of the monochromatic luminosities of jet objects at 25 MHz, 5 GHz, and in
optics. Note that these are independent from the Universe model. We also derived luminosity ratio values such
as:
〈
log
(
L25
Lopt
)〉
G
= 4.40 ± 0.20;
〈
log
(
L5
Lopt
)〉
G
= 2.77 ± 0.13 for galaxies and
〈
log
(
L25
Lopt
)〉
Q
= 5.11 ± 0.14;〈
log
(
L5
Lopt
)〉
Q
= 3.48 ± 0.09 for quasars.
87
ANALYSIS OF PARAMETER RELATIONS OF THE JET SOURCES
We have considered the relations between the magnetic field strength and the redshift and the spectral index,
indicating a large dispersion of these values for jet objects. An analogous character has the relation between
the object linear size and the spectral index and the redshift.
The dependence of jet velocity on the redshift indicates the correlation of these parameters (Fig. 1).
0.0 0.1 0.2 0.3 0.4 0.5 0.6
1E9
1E10
1E11
v
cm
/s
ec
lg(1+z)
Figure 1. The jet propagation velocity against the redshift for jet objects
It is interesting to study the luminosity ratio of objects at different frequency bands due to its independence
from the Universe model. For galaxies and quasars in our sample we derived the evolution trend of luminosity
ratio for decametric and optical bands (Fig. 2), and for centimeter and optical bands (Fig. 3). Note that
these relations indicate the smaller dispersion for the first case (see Fig. 2). This corresponds the synchrotron
mechanism of the object radiation, when the radio sources evolve more rapidly at more higher frequencies
evidently indicating the cosmological evolution.
0.0 0.1 0.2 0.3 0.4 0.5 0.6
1
2
3
4
5
6
7
8
G_25-opt
Q_25-opt
lg
L 25
-
lg
L op
t
lg(1+z)
Figure 2. The ratio of luminosity at 25 MHz and optical luminosity against the redshift for jet objects
We have also seen the relation between the radio spectral index and the redshift for jet objects (Fig. 4).
This plot indicates an quasiperiodic cosmological variation of spectral indices of jet sources.
CONCLUSIONS
The relation between the luminosity of galaxies and quasars and the redshift corresponds to the synchrotron
mechanism of radiation and indicates the cosmological evolution of luminosity.
The evidence of correlation between the jet velocities and redshifts is derived from our jet objects sample.
The value of jet propagation velocity derived from the estimation of the minimal source age points to
the sublight velocity values.
88
0.0 0.1 0.2 0.3 0.4 0.5 0.6
0
1
2
3
4
5
6
G_5-opt
Q_5-opt
lg
L 5 -
lg
L op
t
lg(1+z)
Figure 3. The ratio of luminosity both at 5 GHz and optical against the redshift for jet objects
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0.0
0.5
1.0
1.5
alpha_mean
A
lp
ha
_m
ea
n
Z_mean
Figure 4. The spectral index against the redshift for jet objects
The magnetic field strength of jet objects ranges from 10−2 to 10−5 G.
The relation between the radio spectral index and the redshift for jet sources has a quasiperiodical character.
The characteristic age of jet objects is 106 ÷ 108 years.
[1] Braude S. Ya., Miroshnichenko A. P., Sokolov K. P., et al. Decametric survey of discrete sources in the Northern
Sky. VII // Astrophys. and Space Sci.–1981.–74, N 2.–P. 409–451.
[2] Braude S. Ya., Miroshnichenko A. P., Rashkovski S. L., et al. Decametric survey of discrete sources in the Northern
Sky. XIII // Kinematics and Physics of Celestial Bodies.–2003.–19, N 4.–P. 291–306.
[3] Bridle A., Perley K. Extragalactic Radio Jets // Annu. Rev. Astron. and Astrophys.–1984.–22.–P. 319–358.
[4] Ginzburg V. L. Theoretical Physics and Astrophysics.–Moscow: Nauka, 1987.–487 p. (in Russian).
[5] Kuhr H., Nauber U., Pauling-Toth I., et al. A catalogue of radio sources.–Bonn: Max-Plank-Institute fur Radioas-
tronomie, 1981.–337 p.
[6] Lara L., Cotton W., Feretti L., et al. A new sample of large angular size radio galaxies. I // NRAO Preprint.–2001,
N 3.–46 p.
[7] Lawrence C., Bennett C., Hewitt J., et al. 5 GHz radio structure and optical identifications of sources from the MG
survey. II // Astrophys. J.–1986.–61, N 1.–P. 105–157.
[8] Veron-Cetti M.-P., Veron P. A catalogue of quasars and active nuclei // ESO Scientific Report.–1991.–N 10.–199 p.
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|
| id | nasplib_isofts_kiev_ua-123456789-79610 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 0233-7665 |
| language | English |
| last_indexed | 2025-12-07T18:43:27Z |
| publishDate | 2005 |
| publisher | Головна астрономічна обсерваторія НАН України |
| record_format | dspace |
| spelling | Miroshnichenko, A.P. 2015-04-03T15:20:35Z 2015-04-03T15:20:35Z 2005 Relations of radio sources with jets parameters / A.P. Miroshnichenko // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 86-89. — Бібліогр.: 8 назв. — англ. 0233-7665 https://nasplib.isofts.kiev.ua/handle/123456789/79610 We considered the sample of galaxies and quasars with jets based on observed data. We obtained the magnetic field strength in these objects using the condition of energy equipartition between the relativistic particles and the magnetic field. We determined values of luminosities in the radio band and in optics. The relations of the sample object radio sizes, luminosities, spectral indices, redshift were derived. An estimations of the lifetime for objects with jets were obtained too. en Головна астрономічна обсерваторія НАН України Кинематика и физика небесных тел MS1: Decameter Radioastronomy Relations of radio sources with jets parameters Article published earlier |
| spellingShingle | Relations of radio sources with jets parameters Miroshnichenko, A.P. MS1: Decameter Radioastronomy |
| title | Relations of radio sources with jets parameters |
| title_full | Relations of radio sources with jets parameters |
| title_fullStr | Relations of radio sources with jets parameters |
| title_full_unstemmed | Relations of radio sources with jets parameters |
| title_short | Relations of radio sources with jets parameters |
| title_sort | relations of radio sources with jets parameters |
| topic | MS1: Decameter Radioastronomy |
| topic_facet | MS1: Decameter Radioastronomy |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/79610 |
| work_keys_str_mv | AT miroshnichenkoap relationsofradiosourceswithjetsparameters |