Creation of 2-5 keV and 5-10 keV sky maps using XMM-Newton data
Sky maps are powerful visualisation tools for quicklook analysis of extended sources. The latest sky map in soft X-rays (0.1-2.4 keV) has been created in the 1990's using ROSAT data. By analysing publically available data from XMM-Newton X-ray mission we constructed new sky maps in two energy b...
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| Zitieren: | Creation of 2-5 keV and 5-10 keV sky maps using XMM-Newton data / D.O. Savchenko, D.A. Iakubovskyi // Advances in Astronomy and Space Physics. — 2014. — Т. 4., вип. 1-2. — С. 51-53. — Бібліогр.: 9 назв. — англ. |
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irk-123456789-1198152017-06-10T03:03:23Z Creation of 2-5 keV and 5-10 keV sky maps using XMM-Newton data Savchenko, D.O. Iakubovskyi, D.A. Sky maps are powerful visualisation tools for quicklook analysis of extended sources. The latest sky map in soft X-rays (0.1-2.4 keV) has been created in the 1990's using ROSAT data. By analysing publically available data from XMM-Newton X-ray mission we constructed new sky maps in two energy bands - 2-5 keV and 5-10 keV,complementary to ROSAT data, covering approximately 1% of the sky, and included them in our web-based tool http://skyview.virgoua.org. 2014 Article Creation of 2-5 keV and 5-10 keV sky maps using XMM-Newton data / D.O. Savchenko, D.A. Iakubovskyi // Advances in Astronomy and Space Physics. — 2014. — Т. 4., вип. 1-2. — С. 51-53. — Бібліогр.: 9 назв. — англ. 2227-1481 DOI: 10.17721/2227-1481.4.51-53 http://dspace.nbuv.gov.ua/handle/123456789/119815 en Advances in Astronomy and Space Physics Головна астрономічна обсерваторія НАН України |
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English |
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Sky maps are powerful visualisation tools for quicklook analysis of extended sources. The latest sky map in soft X-rays (0.1-2.4 keV) has been created in the 1990's using ROSAT data. By analysing publically available data from XMM-Newton X-ray mission we constructed new sky maps in two energy bands - 2-5 keV and 5-10 keV,complementary to ROSAT data, covering approximately 1% of the sky, and included them in our web-based tool http://skyview.virgoua.org. |
| format |
Article |
| author |
Savchenko, D.O. Iakubovskyi, D.A. |
| spellingShingle |
Savchenko, D.O. Iakubovskyi, D.A. Creation of 2-5 keV and 5-10 keV sky maps using XMM-Newton data Advances in Astronomy and Space Physics |
| author_facet |
Savchenko, D.O. Iakubovskyi, D.A. |
| author_sort |
Savchenko, D.O. |
| title |
Creation of 2-5 keV and 5-10 keV sky maps using XMM-Newton data |
| title_short |
Creation of 2-5 keV and 5-10 keV sky maps using XMM-Newton data |
| title_full |
Creation of 2-5 keV and 5-10 keV sky maps using XMM-Newton data |
| title_fullStr |
Creation of 2-5 keV and 5-10 keV sky maps using XMM-Newton data |
| title_full_unstemmed |
Creation of 2-5 keV and 5-10 keV sky maps using XMM-Newton data |
| title_sort |
creation of 2-5 kev and 5-10 kev sky maps using xmm-newton data |
| publisher |
Головна астрономічна обсерваторія НАН України |
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2014 |
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http://dspace.nbuv.gov.ua/handle/123456789/119815 |
| citation_txt |
Creation of 2-5 keV and 5-10 keV sky maps using XMM-Newton data / D.O. Savchenko, D.A. Iakubovskyi // Advances in Astronomy and Space Physics. — 2014. — Т. 4., вип. 1-2. — С. 51-53. — Бібліогр.: 9 назв. — англ. |
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Advances in Astronomy and Space Physics |
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2025-07-08T16:39:25Z |
| last_indexed |
2025-07-08T16:39:25Z |
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1837097567447416832 |
| fulltext |
Creation of 2�5 keV and 5�10 keV sky maps
using XMM-Newton data
D.O. Savchenko1∗, D.A. Iakubovskyi1,2
Advances in Astronomy and Space Physics, 4, 51-53 (2014)
© D.O. Savchenko, D.A. Iakubovskyi, 2014
1Bogolyubov Institute of Theoretical Physics, Metrologichna str. 14-b, 03680, Kyiv, Ukraine
2National University �Kyiv-Mohyla Academy�, Skovorody str. 2, 04070, Kyiv, Ukraine
Sky maps are powerful visualisation tools for quicklook analysis of extended sources. The latest sky map in
soft X-rays (0.1�2.4 keV) has been created in the 1990's using ROSAT data. By analysing publically available data
from XMM-Newton X-ray mission we constructed new sky maps in two energy bands � 2�5 keV and 5�10 keV,
complementary to ROSAT data, covering approximately 1% of the sky, and included them in our web-based tool
http://skyview.virgoua.org.
Key words: X-rays: general, virtual observatory tools
introduction
Usually, astronomers deal with catalogues of
point sources. However, if the source is extended
(i. e. its size is comparable or even bigger than the
point spread function of the instrument, a more so-
phisticated method of scienti�c data visualisation is
needed. The most common method of such visualisa-
tion is building sky maps � specially processed series
of two-dimensional images in di�erent energy bands.
An example of such a map for X-ray astronomy is
all-sky map in 0.1�2.4 keV band made by ROSAT
X-ray satellite [7, 9] observations. This all-sky map
also exists as an interactive web-tool1.
Following the end of the ROSAT mission, sev-
eral missions in the keV range have been in opera-
tion. These missions have covered a minor part of
the sky (not more than several percent) but with a
much better sensitivity and a wider energy range as
compared with ROSAT. In this paper, we present
the interactive maps in 2�5 and 5�10 keV range. For
these maps, we use publically available observations
by MOS cameras [8] of the XMM-Newton [4] X-ray
mission. Special attention was paid to the handling
of the most important background components, in-
cluding soft proton �ares and quiescent particle back-
ground, see the corresponding web-page2 for detailed
properties of XMM-Newton background. The ob-
tained map is on the website of Virtual Roentgen
and Gamma Observatory in Ukraine3.
methods
In order to construct the sky maps, we �rst
downloaded all publically available (as of July 1,
2013) observation data �les for MOS [8] cameras
of the XMM-Newton X-ray observatory [4] avail-
able on the HEASARC data archive4. These
data �les were processed using Extended Sources
Analysis Software (ESAS) package5 [5] specially
developed for analysis of extended sources at the
NASA/GSFC XMM-Newton Guest Observer Facil-
ity6 in cooperation with the XMM-Newton Science
Operation Centre7 and the XMM-Newton Back-
ground Working Group8. It is publically available
as part of XMM-Newton Science Analysis System
(SAS) v.13.5.0. The methodology of ESAS soft-
ware is based on detailed modeling and/or subtrac-
tion of various background components (see the web-
page2 for complete list) experienced by MOS and
PN cameras on-board XMM-Newton cosmic mission
using the ��rst principles� as much as possible. To
model instrumental background, ESAS software relies
on �lter-wheel-closed data and the data from the un-
exposed corners of archived observations, rather than
�blank sky� data (contaminated to an unknown level
by di�erent variable background components) used
by a number of other methods. This is essential for
analysis of very faint sky regions (e. g. galaxy clus-
ter outskirts) dominated by the background (rather
∗dsavchenko@bitp.kiev.ua
1http://heasarc.gsfc.nasa.gov/cgi-bin/Tools/xraybg/xraybg.pl
2http://www.star.le.ac.uk/~amr30/BG/BGTable.html
3http://skyview.virgoua.org
4http://heasarc.nasa.gov
5http://heasarc.gsfc.nasa.gov/docs/xmm/esas/cookbook/xmm-esas.html
6http://heasarc.gsfc.nasa.gov/docs/xmm/xmmgof.html
7http://xmm.esac.esa.int
8http://xmm2.esac.esa.int/external/xmm_sw_cal/background
51
Advances in Astronomy and Space Physics D.O. Savchenko, D.A. Iakubovskyi
than the source) emission. The obtained data prod-
ucts � �ltered event lists, images, lightcurves and
spectra � are produced in FITS [2, 3] format for
user-de�ned regions within the XMM-Newton �eld-
of-view. Here, an �event� is a result of instanta-
neous positive detection in one or several adjacent
CCD pixels. A single photon impacting on the CCD
may produce a substantial signal in adjacent pix-
els causing so-called multiple (e. g. double, triple,
quadruple) events. The standard selection procedure
used in our analysis takes into account single, dou-
ble, triple and quadruple events for MOS cameras.
According to [6] the procedure based on analysis of
event patterns allows to reject approximately 99%
of events caused by high-energy (∼ 100MeV) cosmic
rays, thus signi�cantly reducing the amount of data
telemetry.
Table 1: General properties of MOS observations used
in our analysis.
Camera MOS1 MOS2
No. of observations 3942 4022
No. of data �les 4029 4104
Cleaned exposure, Ms 77.9 81.5
Our data reduction is started from production
of �ltered event lists using ESAS script mos-filter.
This script e�ectively removes time intervals a�ected
by highly variable background components � soft
proton �ares, see [5] and the web-page2. We used
the standard �lters and cuts provided by ESAS soft-
ware. For example, we selected single, double, triple
and quadruple events (described by event PATTERN
<= 12) of highest quality (described by FLAG ==
0). Such a selection based on FLAG keyword ex-
cludes events out of instrument FoV, near CCD cor-
ners and �hot pixels� etc. It is generally recom-
mended9,10 to select FLAG == 0 for high-quality
spectral analysis. The main parameters for ob-
tained event lists are shown in Table 1. The left-
over MOS event lists were processed by ESAS scripts
mos-spectra and mos_back, resulting in observed
and modelled quiscent particle background spectra,
exposure maps, count images for selected energy
ranges, and modelled particle background count im-
ages. The resulting images and exposure maps of
individual observations are then combined by ESAS
scripts merge_comp_xmm and bin_image_merge into
count-rate images of sky regions with size 22◦ × 22◦
and minimal pixel size 2.5′′ × 2.5′′. Point sources
are not excluded, although very bright point sources
observed with timing mode (such as BYCam, see
Fig. 2) have not been processed by ESAS and there-
fore do not appear on the map. For the sky map, we
chose two energy ranges � 2�5 keV and 5�10 keV �
motivated by:
� Their negligible contamination by remaining
Solar Wind Charge Exchange background com-
ponent, see [5] the web-page2 for details; and
� The complementarity to existing ROSAT all-
sky map1 in 0.1�2.4 keV.
For sky map visualisation, we used the standard
NASA skyview.jar tool11. This tool selects ap-
propriate images overlapping with a given sky re-
gion and samples them to the given pixel size. The
Sutherland-Hodgman clipping algorithm was used to
resample images. This method treats the output
pixel grid as a window over the input images grid and
integrates the �ux within each output pixel exactly.
The output image can be produced at the given sky
coordinates and projection. The obtained images in
FITS [2, 3] format are available for a quick look and
can be directly downloaded from the web-page3.
results
We constructed sky maps in 2�5 keV and 5�10 keV
bands using ∼4000 publically available observations
of MOS cameras on-board the XMM-Newton X-ray
cosmic mission. Positions of given observations and
their basic properties are shown in Fig. 1 and Ta-
ble 1, respectively. The produced maps are cleaned
from variable soft proton component and instrumen-
tal background with the help of standard analysis for
extended sources � ESAS software5 � and added to
the web-interface of Virtual Roentgen and Gamma-
Ray Observatory in Ukraine3, see Figs 3 and 4 as
examples. The obtained maps cover approximately
1% of all sky, see Fig. 1 for details. They are comple-
mentary to existing ROSAT all-sky map in soft X-
rays (0.1�2.4 keV) as well as usual X-ray catalogues
of point sources.
acknowledgement
We thank Yuri Izotov, Vladimir Savchenko, Igor
Telezhinsky, Ievgen Vovk and the anonymous Ref-
eree for their comments and suggestions. This work
was supported in part by the Program of Cosmic
Research of the National Academy of Sciences of
Ukraine and the State Programme of Implementa-
tion of Grid Technology in Ukraine.
references
[1] BaumgartnerW.H., Tueller J., MarkwardtC.B. et al.
2013, ApJS, 207, 19
[2] CalabrettaM.R. & GreisenE.W. 2002, A&A, 395, 1077
[3] GreisenE.W. & CalabrettaM.R. 2002, A&A, 395, 1061
[4] JansenF., LumbD., Altieri B. et al. 2001, A&A, 365, L1
[5] KuntzK.D. & Snowden S. L. 2008, A&A, 478, 575
9http://xmm.esac.esa.int/external/xmm_user_support/documentation/sas_usg/USG
10http://xmm.esac.esa.int/external/xmm_user_support/documentation/uhb
11http://skyview.gsfc.nasa.gov/current/jar/skyviewinajar.html
52
Advances in Astronomy and Space Physics D.O. Savchenko, D.A. Iakubovskyi
Fig. 1: Positions (in galactic coordinates) of XMM-
Newton observations used in our analysis. The �eld-of-
views of XMM-Newton observations are given in natural
values, so one can easily recognize the zones observed by
XMM-Newton covering about 1% of all sky.
Fig. 2: An example of very bright point source obser-
vation � polar BYCam in 2�5 keV. The units are in
cts/s/deg2. The position of BYCam coincides with cen-
tral CCD of MOS instruments. Because this point source
is very bright (& 1mCrab [1]), it was not observed in
usual imaging mode and therefore appears as a �gap� in
the sky map.
Fig. 3: A 2�5 keV image of 1 square degree around
Perseus cluster of galaxies. The units are in cts/s/deg2.
Fig. 4: The same as in Figure 3 but for Milky Way centre
in 5�10 keV range.
[6] LumbD.H., WarwickR. S., PageM. & De LucaA. 2002,
A&A, 389, 93
[7] Snowden S. L., FreybergM. J., PlucinskyP.P. et al. 1995,
ApJ, 454, 643
[8] TurnerM. J. L., AbbeyA., ArnaudM. et al. 2001, A&A,
365, L27
[9] VogesW., AschenbachB., BollerT. et al. 1999, A&A,
349, 389
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