Bright X-ray galaxies in SDSS filaments
Eighteen bright X-ray emitting galaxies were found in nearby filaments within the SDSS region. Basic X-ray spectral parameters were estimated for these galaxies using a power law model with photoelectric absorption. A close pair of X-ray galaxies was found.
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Головна астрономічна обсерваторія НАН України
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| Цитувати: | Bright X-ray galaxies in SDSS filaments / A.V. Tugay // Advances in Astronomy and Space Physics. — 2013. — Т. 3., вип. 2. — С. 116-119. — Бібліогр.: 14 назв. — англ. |
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irk-123456789-1196482017-06-08T03:06:30Z Bright X-ray galaxies in SDSS filaments Tugay, A.V. Eighteen bright X-ray emitting galaxies were found in nearby filaments within the SDSS region. Basic X-ray spectral parameters were estimated for these galaxies using a power law model with photoelectric absorption. A close pair of X-ray galaxies was found. 2013 Article Bright X-ray galaxies in SDSS filaments / A.V. Tugay // Advances in Astronomy and Space Physics. — 2013. — Т. 3., вип. 2. — С. 116-119. — Бібліогр.: 14 назв. — англ. 2227-1481 http://dspace.nbuv.gov.ua/handle/123456789/119648 en Advances in Astronomy and Space Physics Головна астрономічна обсерваторія НАН України |
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English |
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Eighteen bright X-ray emitting galaxies were found in nearby filaments within the SDSS region. Basic X-ray spectral parameters were estimated for these galaxies using a power law model with photoelectric absorption. A close pair of X-ray galaxies was found. |
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Article |
| author |
Tugay, A.V. |
| spellingShingle |
Tugay, A.V. Bright X-ray galaxies in SDSS filaments Advances in Astronomy and Space Physics |
| author_facet |
Tugay, A.V. |
| author_sort |
Tugay, A.V. |
| title |
Bright X-ray galaxies in SDSS filaments |
| title_short |
Bright X-ray galaxies in SDSS filaments |
| title_full |
Bright X-ray galaxies in SDSS filaments |
| title_fullStr |
Bright X-ray galaxies in SDSS filaments |
| title_full_unstemmed |
Bright X-ray galaxies in SDSS filaments |
| title_sort |
bright x-ray galaxies in sdss filaments |
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Головна астрономічна обсерваторія НАН України |
| publishDate |
2013 |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/119648 |
| citation_txt |
Bright X-ray galaxies in SDSS filaments / A.V. Tugay // Advances in Astronomy and Space Physics. — 2013. — Т. 3., вип. 2. — С. 116-119. — Бібліогр.: 14 назв. — англ. |
| series |
Advances in Astronomy and Space Physics |
| work_keys_str_mv |
AT tugayav brightxraygalaxiesinsdssfilaments |
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2025-07-08T16:19:55Z |
| last_indexed |
2025-07-08T16:19:55Z |
| _version_ |
1837096340916535296 |
| fulltext |
Bright X-ray galaxies in SDSS �laments
A. V.Tugay∗
Advances in Astronomy and Space Physics, 3, 116-119 (2013)
© A.V.Tugay, 2013
Faculty of Physics, Taras Shevchenko National University of Kyiv, Glushkova ave. 4, 03127 Kyiv, Ukraine
Eighteen bright X-ray emitting galaxies were found in nearby �laments within the SDSS region. Basic X-ray
spectral parameters were estimated for these galaxies using a power law model with photoelectric absorption. A
close pair of X-ray galaxies was found.
Key words: X-rays: galaxies, large-scale structure of Universe
introduction
The large-scale structure (LSS) of the observable
Universe contains clusters and groups of galaxies
combined into �laments. The problem of (galaxy)
�lament detection in redshift space is complex, so
its solution methods are usually tested on a mod-
elled LSS obtained using N-body simulations. Smith
et al. [7] found 53 real �laments for the Sloan Digi-
tal Sky Survey (SDSS) galaxies at redshift z < 0.13.
In this paper, the �laments were considered as elon-
gated structures that contain su�cient groups and
clusters for building a minimal spanning tree in red-
shift space. However, such �laments cover only a
relatively small part of SDSS redshift-space volume
available for LSS studying. Therefore, new methods
must be developed to search the �laments using all
SDSS redshifts, and on smaller scales. An attempt to
develop and apply such a new method to SDSS vol-
ume, will be the subject of our future work (where
we intend to use single galaxies instead of groups or
clusters). In this paper, however, we con�ned our-
selves to the consideration of 53 �laments from [7].
The goal of this work was to describe X-ray emis-
sion of galaxies in �laments, which can in the future
be compared with other high-energy sources in the
large-scale structures of the Universe (isolated galax-
ies, clusters, walls). In [9] it was shown that outside
of the Local Supercluster it is only possible to de-
tect galaxies with active galactic nuclei (AGN) in
the X-ray band, therefore the �laments must con-
tain bright X-ray emitting AGN's. X-ray galaxies in
the �laments are established in [7] and their spectra
are considered here.
samples
A sample of 5021 X-ray galaxies from [8] was used
for the search of �lament galaxies. These galaxies
were selected from the Incremental Second XMM-
Newton Serendipitous Source Catalogue (2XMMi)
[13] of X-ray sources detected by the XMM-Newton
observatory. 2092 of them lie in the main SDSS re-
gion of sky (110◦ < α < 250◦, −10◦ < δ < 70◦).
Only the brightest X-ray sources are appropriate
for spectral �tting. After the inspection of prelimi-
nary spectra of 2XMMi sources in Vizier database,
the minimal limiting value of X-ray �ux FX,min =
3.7 · 10−13 erg/cm2 was picked. It is assumed here
that X-ray spectra can be built only for galaxies with
FX > FX,min. 978 of the 5021 X-ray galaxies satisfy
this condition.
The second condition for galaxy selection was
that the galaxy should be inside one of 53 SDSS
�laments, established in [7]. These �laments were
found with multiscale probability methods in which
the size of structures in redshift space is assumed
to be ∆z = 0.005. In the present work, �laments
from [7] were visually inspected on the sky distri-
bution of galaxies in slices with ∆z = 0.023, which
corresponds to the size of void (100Mpc). 53 �la-
ments from [7] occupy only �ve slices of 100Mpc.
An example of a slice is shown in Fig. 1. Numbers
of galaxies in slices are presented in Table 1. Among
335 bright X-ray galaxies in the SDSS region, only 18
were found in the mentioned �laments. During the
selection, several galaxies located inside or very close
to the X-ray clusters, were detected. Although these
clusters can be considered to be part of a �lament,
such galaxies were excluded to avoid the problem of
distinction of radiation from galaxy, from that of the
intergalactic hot gas. To estimate the upper bound of
a possible number of X-ray galaxies in �laments, an
assumption was made that all galaxies outside clus-
ters are located in �laments. General characteristics
of the obtained galaxies are presented in Table 2.
spectral fitting
Cross-correlation of XMM and SDSS sources was
performed in [6], however there was no detailed study
of single galaxies. Basic spectral characteristics of
bright �lament galaxies are presented in Table 3. A
power law model of the X-ray spectrum with photo-
electric absorption was used in this analysis. Galac-
tic absorption was taken from [14]. Spectral param-
∗tugay.anatoliy@gmail.com
116
Advances in Astronomy and Space Physics A.V.Tugay
Table 1: Number of X-ray galaxies in the SDSS by distances.
Radial velocity, Bright X-ray
km/s Filaments in [7] X-ray galaxies Notable Objects galaxies
0-4000 207 Local Supercluster 79
4000-11000 5 214 Coma Supercluster 60
11000-18000 12 196 31
18000-25000 21 212 Sloan Great Wall 37
25000-32000 10 148 29
32000-39000 5 113 12
39000-46000 109 10
46000-53000 70 11
53000-60000 73 7
Distant 555 59
Total 53 2092 335
eters for some galaxies, when possible, were taken
from literature. Nine galaxies had no spectral anal-
ysis in previous works, thus it was conducted in the
present work. These galaxies were mentioned previ-
ously only in AGN catalogues such as [12], and their
cross-correlation with XMM sources was mentioned
in [6]. There are several notes for the few selected
galaxies.
2MASX J12034921+0205575. This Seyfert 1
galaxy has �ve references in the SIMBAD database,
including [6, 12] and 3 older optical surveys. 2XMMi
database contains a preliminary spectrum for this
galaxy, however the full archive of observation data
�les is not available for downloading.
2MASX J09590662+1301351 and 2MASX
J09591475+1259161. This pair of bright X-ray
galaxies has angular distance of 3 arcmin, which
corresponds to a spatial distance of 140 kpc. They
can interact or be physically bound.
conclusions
Eighteen bright X-ray galaxies in SDSS �laments
were found. The most common type of such galaxies
is Seyfert 1. Spectral parameters for nine galaxies
were estimated. Since the number of X-ray sources
in �laments is very small, X-ray observations cannot
be used for the detection of new �laments. There-
fore, the procedure of describing LSS in the high-
energy band should include a detailed description of
the �laments, on the basis of optical galaxy surveys,
statistical studies of X-ray sources in a large homo-
geneous volume, and comparison of parameters of
X-ray extragalactic sources inside and outside �la-
ments. Such a study is going to be performed in our
future works.
acknowledgement
The author is thankful to the Sloan Digital Sky
Survey team. Funding for the SDSS has been pro-
vided by the Alfred P. Sloan Foundation, the US De-
partment of Energy, the Japanese Monbukagakusho,
and the Max Planck Society. The SDSS Web site is
http://www.sdss.org.
The author is also thankful to the anonymous ref-
eree for very useful advice on improving this work
and propositions of its continuation. The author also
acknowledges to A.Vasylenko for his help with spec-
tral �tting.
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117
Advances in Astronomy and Space Physics A.V.Tugay
Table 2: General properties of bright X-ray galaxies.
Coordinate V3K, X-ray �ux,
Object name code SIMBAD Type km/s 10−12 erg/cm2
2XMMi J082912.8+500652 0829+5007 Seyfert 1 13141 1.91±0.11
2MASX J08413787+5455069 0842+5455 Seyfert 1 13512 3.83±0.14
2MASX J09590662+1301351 0959+1301 Galaxy 11296 1.25±0.03
2MASX J09591475+1259161 0959+1259 Galaxy 10619 1.39±0.03
2MASS J10003549+0524285 1001+0524 QSO 23905 0.99±0.04
Mrk 176 1133+5257 Seyfert 1 8325 0.62±0.02
NGC 3921 1151+5505 Interacting Galaxies 6017 0.42±0.01
2MASX J12034921+0205575 1204+0206 Seyfert 1 24714 1.09±0.11
2E 2620 1214+1403 Seyfert 1 24581 10.97±0.02
NGC 4686 1247+5432 Galaxy in Group 5181 1.13±0.03
MCG+07-28-006 1324+4318 Seyfert 2 8374 1.12±0.04
2XMM J134245.8+403913 1343+4039 X-ray source 26889 0.59±0.03
2MASS J14134834+4400141 1414+4400 Seyfert 1 26842 0.74±0.02
NGC 5548 1418+2508 Seyfert 1 5358 74.44±0.13
Mrk 684 1431+2817 Seyfert 1 13949 7.54±0.06
87GB 150115.3+102756 1501+1028 AGN 28668 0.55±0.05
Mrk 841 1504+1026 Seyfert 1 11126 35.02±0.15
2MASX J15113367+0545479 1512+0546 AGN 25065 0.43±0.01
Table 3: Spectral properties of bright X-ray galaxies.
Galactic NH ,
Target 1022 cm−2 NH , 10
22 cm−2 Photon index χ2/d.o.f. Source
0829+5007 0.046 0.05 2.64±0.08 102.4/101 [2]
0842+5455 0.038 0.31±0.02 1.56±0.06 109/135 This work
0959+1301 0.032 12.7±2.5 1.34±0.29 15.8/16 This work
0959+1259 0.032 0.77 ± 0.05 1.88 ± 0.08 206/267 [4]
1001+0524 0.027 <0.01 2.26±0.11 35/28 This work
1133+5257 0.011 12.7±2.5 1.34±0.29 11.4/11 This work
1151+5505 0.010 1.93±0.20 1.55±0.10 93/86 [5]
1214+1403 0.030 0.043±0.006 2.07±0.01 896/746 This work
1247+5432 0.015 0.024±0.001 2.00±0.05 119/61 [10]
1324+4318 0.015 0.06+0.34
−0.04 2.74+2.40
−0.67 141/68 [4]
1343+4039 0.008 3.8±1.2 1.25±0.37 10.6/11 This work
1414+4400 0.009 16.7+4.5
−5.6 1.55+0.24
−0.23 63/75 [3]
1418+2508 0.017 0.02 1.65 [11]
1431+2817 0.016 <0.01 2.45±0.02 400/286 This work
1501+1028 0.024 <0.01 1.48±0.01 1022/770 This work
1504+1026 0.024 0.02 1.75±0.05 [1]
1512+0546 0.036 0.08±0.02 2.22±0.19 62/58 This work
118
Advances in Astronomy and Space Physics A.V.Tugay
Fig. 1: Sky distribution of SDSS galaxies with radial velocities between 11000 and 18000 km/s. Triangles are X-ray
galaxies with FX < FX,min, squares � bright X-ray galaxies with FX > FX,min, large rectangles � �laments from [7],
double squares � galaxies in �laments which are considered in this work.
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