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J/AJ/153/220            NORAS II. I. First results            (Bohringer+, 2017)

The extended northern ROSAT galaxy cluster survey (NORAS II). I. Survey construction and first results. Bohringer H., Chon G., Retzlaff J., Trumper J., Meisenheimer K., Schartel N. <Astron. J., 153, 220-220 (2017)> =2017AJ....153..220B (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Clusters, galaxy ; X-ray sources Keywords: cosmology: observations - galaxies: clusters: general - surveys - X-rays: galaxies: clusters Abstract: As the largest, clearly defined building blocks of our universe, galaxy clusters are interesting astrophysical laboratories and important probes for cosmology. X-ray surveys for galaxy clusters provide one of the best ways to characterize the population of galaxy clusters. We provide a description of the construction of the NORAS II galaxy cluster survey based on X-ray data from the northern part of the ROSAT All-Sky Survey. NORAS II extends the NORAS survey down to a flux limit of 1.8x10-12erg/s/cm2 (0.1-2.4keV), increasing the sample size by about a factor of two. The NORAS II cluster survey now reaches the same quality and depth as its counterpart, the southern REFLEX II survey, allowing us to combine the two complementary surveys. The paper provides information on the determination of the cluster X-ray parameters, the identification process of the X-ray sources, the statistics of the survey, and the construction of the survey selection function, which we provide in numerical format. Currently NORAS II contains 860 clusters with a median redshift of z=0.102. We provide a number of statistical functions, including the log N-log S and the X-ray luminosity function and compare these to the results from the complementary REFLEX II survey. Using the NORAS II sample to constrain the cosmological parameters, σ8 and Ωm, yields results perfectly consistent with those of REFLEX II. Overall, the results show that the two hemisphere samples, NORAS II and REFLEX II, can be combined without problems into an all-sky sample, just excluding the zone of avoidance. Description: The NOrthern ROSAT All-Sky (NORAS) galaxy cluster survey project is based on the ROSAT All-Sky Survey (RASS; Trumper 1993Sci...260.1769T), which is the only full-sky survey conducted with an imaging X-ray telescope. We have already used RASS for the construction of the cluster catalogs of the NORAS I project. While NORAS I was as a first step focused on the identification of galaxy clusters among the RASS X-ray sources showing a significant extent, the complementary REFLEX I sample in the southern sky was strictly constructed as a flux-limited cluster sample. A major extension of the REFLEX I sample, which roughly doubles the number of clusters, REFLEX II (Bohringer et al. 2013, Cat. J/A+A/555/A30), was recently completed. It is by far the largest high-quality sample of X-ray-selected galaxy clusters. The NORAS II survey now reaches a flux limit of 1.8*10-12erg/s/cm2 in the 0.1-2.4keV band. Redshifts have been obtained for all of the 860 clusters in the NORAS II catalog, except for 25 clusters for which observing campaigns are scheduled. Thus with 3% missing redshifts we can already obtain a very good view of the properties of the NORAS II cluster sample and obtain some first results. The NORAS II survey covers the sky region north of the equator outside the band of the Milky Way (|bII|≥20°). We also excise a region around the nearby Virgo cluster of galaxies that extends over several degrees on the sky, where the detection of background clusters is hampered by bright X-ray emission. This region is bounded in right ascension by R.A.=185°-191.25° and in declination by decl.=6°-15° (an area of ∼53deg2). With this excision, the survey area covers 4.18 steradian (13519deg2, a fraction of 32.7% of the sky). NORAS II is based on the RASS product RASS III (Voges et al. 1999, Cat. IX/10), which was also used for REFLEX II. The NORAS II survey was constructed in a way identical to REFLEX II with a nominal flux limit of 1.8*10-12erg/s/cm2. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 52 21666 *Sensitivity map of the NORAS II survey table3.dat 16 21650 *Effective sky coverage of NORAS II table4.dat 1632 21666 *Survey mask for NORAS II
Note on table*.dat: NORAS II = extended NOrthern ROSAT All-Sky (NORAS) galaxy cluster survey.
See also: IX/29 : ROSAT All-Sky Survey Faint Source Catalog (Voges+ 2000) IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999) J/MNRAS/429/3272 : REFLEX II flux-limited supercluster sample (Chon+, 2013) J/A+A/555/A30 : REFLEX II. Properties of the survey (Boehringer+ 2013) J/A+A/535/A4 : X-ray galaxy clusters study (Reichert+, 2011) J/A+A/499/357 : REFLEX galaxies redshifts (Guzzo+, 2009) J/A+A/425/367 : REFLEX Galaxy Cluster Survey catalogue (Boehringer+, 2004) J/ApJS/140/239 : RASS: clusters of galaxies around SGP (Cruddace+, 2002) J/ApJ/580/774 : X-ray cluster of galaxies behind the MW (Ebeling+, 2002) J/ApJS/129/435 : NORAS galaxy cluster survey. I. (Bohringer+, 2000) J/ApJ/514/148 : ROSAT survey of bright galaxies clusters (De Grandi+, 1999) J/MNRAS/301/881 : The ROSAT brightest cluster sample - I. (Ebeling+, 1998) J/MNRAS/281/799 : XBACs, the sample (Ebeling+, 1996) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 8 F8.4 deg RAdeg Right Ascension in decimal degrees (J2000) (1) 10- 16 F7.4 deg DEdeg Declination in decimal degrees (J2000) (1) 18- 25 F8.3 --- Sense ? Sensitivity (2) 27- 34 F8.6 deg2 Size Size of the sky pixel 36- 43 F8.4 deg GLON Galactic longitude (lII) (1) 45- 52 F8.4 deg GLAT Galactic latitude (bII) (1)
Note (1): Equatorial and galactic coordinates of the sky pixel for the epoch J2000. Note (2): The number of photons that can be detected in the ROSAT All-Sky Survey (RASS) at that sky pixel for a source at the nominal flux limit, FX=1.8*10-12erg/s/cm2. A blank indicates an infinite number.
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 7 F7.3 fW/m2 Flux Flux limit for 20 source photon detection (1) 9- 16 F8.6 --- Counts Fraction of sky survey area of NORAS II (13519 deg2) (2)
Note (1): In units of 10-12erg/s/cm2 in the 0.1-2.4keV band for a detection of at least 20 source photons. Note (2): Covered up to this flux limit. The NORAS II survey covers the sky region north of the equator outside the band of the Milky Way (|bII|≥20°). We also excise a region around the nearby Virgo cluster of galaxies that extends over several degrees on the sky, where the detection of background clusters is hampered by bright X-ray emission. This region is bounded in right ascension by R.A.=185°-191.25° and in declination by decl.=6°-15° (an area of ∼53deg2). With this excision, the survey area covers 4.18 steradian (13519deg2, a fraction of 32.7% of the sky)
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 8 F8.4 deg RAdeg Right Ascension in decimal degrees (J2000) 10- 16 F7.4 deg DEdeg Declination in decimal degrees (J2000) 18- 25 F8.5 fW/m2 L0.005 Minimum X-ray luminosity at z=0.005 (1) 27- 34 F8.5 fW/m2 L0.010 Minimum X-ray luminosity at z=0.010 (1) 36- 43 F8.5 fW/m2 L0.015 Minimum X-ray luminosity at z=0.015 (1) 45- 52 F8.5 fW/m2 L0.020 Minimum X-ray luminosity at z=0.020 (1) 54- 61 F8.5 fW/m2 L0.025 Minimum X-ray luminosity at z=0.025 (1) 63- 70 F8.5 fW/m2 L0.030 Minimum X-ray luminosity at z=0.030 (1) 72- 79 F8.5 fW/m2 L0.035 Minimum X-ray luminosity at z=0.035 (1) 81- 88 F8.5 fW/m2 L0.040 Minimum X-ray luminosity at z=0.040 (1) 90- 97 F8.5 fW/m2 L0.045 Minimum X-ray luminosity at z=0.045 (1) 99-106 F8.5 fW/m2 L0.050 Minimum X-ray luminosity at z=0.050 (1) 108-115 F8.5 fW/m2 L0.055 Minimum X-ray luminosity at z=0.055 (1) 117-124 F8.5 fW/m2 L0.060 Minimum X-ray luminosity at z=0.060 (1) 126-133 F8.5 fW/m2 L0.065 Minimum X-ray luminosity at z=0.065 (1) 135-142 F8.5 fW/m2 L0.070 Minimum X-ray luminosity at z=0.070 (1) 144-151 F8.5 fW/m2 L0.075 Minimum X-ray luminosity at z=0.075 (1) 153-160 F8.5 fW/m2 L0.080 Minimum X-ray luminosity at z=0.080 (1) 162-169 F8.5 fW/m2 L0.085 Minimum X-ray luminosity at z=0.085 (1) 171-178 F8.5 fW/m2 L0.090 Minimum X-ray luminosity at z=0.090 (1) 180-187 F8.5 fW/m2 L0.095 Minimum X-ray luminosity at z=0.095 (1) 189-196 F8.5 fW/m2 L0.100 Minimum X-ray luminosity at z=0.100 (1) 198-205 F8.5 fW/m2 L0.105 Minimum X-ray luminosity at z=0.105 (1) 207-214 F8.5 fW/m2 L0.110 Minimum X-ray luminosity at z=0.110 (1) 216-223 F8.5 fW/m2 L0.115 Minimum X-ray luminosity at z=0.115 (1) 225-232 F8.5 fW/m2 L0.120 Minimum X-ray luminosity at z=0.120 (1) 234-241 F8.5 fW/m2 L0.125 Minimum X-ray luminosity at z=0.125 (1) 243-250 F8.5 fW/m2 L0.130 Minimum X-ray luminosity at z=0.130 (1) 252-259 F8.5 fW/m2 L0.135 Minimum X-ray luminosity at z=0.135 (1) 261-268 F8.5 fW/m2 L0.140 Minimum X-ray luminosity at z=0.140 (1) 270-277 F8.5 fW/m2 L0.145 Minimum X-ray luminosity at z=0.145 (1) 279-286 F8.5 fW/m2 L0.150 Minimum X-ray luminosity at z=0.150 (1) 288-295 F8.5 fW/m2 L0.155 Minimum X-ray luminosity at z=0.155 (1) 297-304 F8.5 fW/m2 L0.160 Minimum X-ray luminosity at z=0.160 (1) 306-313 F8.5 fW/m2 L0.165 Minimum X-ray luminosity at z=0.165 (1) 315-322 F8.5 fW/m2 L0.170 Minimum X-ray luminosity at z=0.170 (1) 324-331 F8.5 fW/m2 L0.175 Minimum X-ray luminosity at z=0.175 (1) 333-340 F8.5 fW/m2 L0.180 Minimum X-ray luminosity at z=0.180 (1) 342-349 F8.5 fW/m2 L0.185 Minimum X-ray luminosity at z=0.185 (1) 351-358 F8.5 fW/m2 L0.190 Minimum X-ray luminosity at z=0.190 (1) 360-367 F8.5 fW/m2 L0.195 Minimum X-ray luminosity at z=0.195 (1) 369-377 F9.5 fW/m2 L0.200 Minimum X-ray luminosity at z=0.200 (1) 379-387 F9.5 fW/m2 L0.205 Minimum X-ray luminosity at z=0.205 (1) 389-397 F9.5 fW/m2 L0.210 Minimum X-ray luminosity at z=0.210 (1) 399-407 F9.5 fW/m2 L0.215 Minimum X-ray luminosity at z=0.215 (1) 409-417 F9.5 fW/m2 L0.220 Minimum X-ray luminosity at z=0.220 (1) 419-427 F9.5 fW/m2 L0.225 Minimum X-ray luminosity at z=0.225 (1) 429-437 F9.5 fW/m2 L0.230 Minimum X-ray luminosity at z=0.230 (1) 439-447 F9.5 fW/m2 L0.235 Minimum X-ray luminosity at z=0.235 (1) 449-457 F9.5 fW/m2 L0.240 Minimum X-ray luminosity at z=0.240 (1) 459-467 F9.5 fW/m2 L0.245 Minimum X-ray luminosity at z=0.245 (1) 469-477 F9.5 fW/m2 L0.250 Minimum X-ray luminosity at z=0.250 (1) 479-487 F9.5 fW/m2 L0.255 Minimum X-ray luminosity at z=0.255 (1) 489-497 F9.5 fW/m2 L0.260 Minimum X-ray luminosity at z=0.260 (1) 499-507 F9.5 fW/m2 L0.265 Minimum X-ray luminosity at z=0.265 (1) 509-517 F9.5 fW/m2 L0.270 Minimum X-ray luminosity at z=0.270 (1) 519-527 F9.5 fW/m2 L0.275 Minimum X-ray luminosity at z=0.275 (1) 529-537 F9.5 fW/m2 L0.280 Minimum X-ray luminosity at z=0.280 (1) 539-547 F9.5 fW/m2 L0.285 Minimum X-ray luminosity at z=0.285 (1) 549-557 F9.5 fW/m2 L0.290 Minimum X-ray luminosity at z=0.290 (1) 559-567 F9.5 fW/m2 L0.295 Minimum X-ray luminosity at z=0.295 (1) 569-577 F9.5 fW/m2 L0.300 Minimum X-ray luminosity at z=0.300 (1) 579-587 F9.5 fW/m2 L0.305 Minimum X-ray luminosity at z=0.305 (1) 589-597 F9.5 fW/m2 L0.310 Minimum X-ray luminosity at z=0.310 (1) 599-607 F9.5 fW/m2 L0.315 Minimum X-ray luminosity at z=0.315 (1) 609-617 F9.5 fW/m2 L0.320 Minimum X-ray luminosity at z=0.320 (1) 619-627 F9.5 fW/m2 L0.325 Minimum X-ray luminosity at z=0.325 (1) 629-637 F9.5 fW/m2 L0.330 Minimum X-ray luminosity at z=0.330 (1) 639-647 F9.5 fW/m2 L0.335 Minimum X-ray luminosity at z=0.335 (1) 649-657 F9.5 fW/m2 L0.340 Minimum X-ray luminosity at z=0.340 (1) 659-667 F9.5 fW/m2 L0.345 Minimum X-ray luminosity at z=0.345 (1) 669-677 F9.5 fW/m2 L0.350 Minimum X-ray luminosity at z=0.350 (1) 679-687 F9.5 fW/m2 L0.355 Minimum X-ray luminosity at z=0.355 (1) 689-697 F9.5 fW/m2 L0.360 Minimum X-ray luminosity at z=0.360 (1) 699-707 F9.5 fW/m2 L0.365 Minimum X-ray luminosity at z=0.365 (1) 709-717 F9.5 fW/m2 L0.370 Minimum X-ray luminosity at z=0.370 (1) 719-727 F9.5 fW/m2 L0.375 Minimum X-ray luminosity at z=0.375 (1) 729-737 F9.5 fW/m2 L0.380 Minimum X-ray luminosity at z=0.380 (1) 739-747 F9.5 fW/m2 L0.385 Minimum X-ray luminosity at z=0.385 (1) 749-757 F9.5 fW/m2 L0.390 Minimum X-ray luminosity at z=0.390 (1) 759-767 F9.5 fW/m2 L0.395 Minimum X-ray luminosity at z=0.395 (1) 769-777 F9.5 fW/m2 L0.400 Minimum X-ray luminosity at z=0.400 (1) 779-787 F9.5 fW/m2 L0.405 Minimum X-ray luminosity at z=0.405 (1) 789-797 F9.5 fW/m2 L0.410 Minimum X-ray luminosity at z=0.410 (1) 799-807 F9.5 fW/m2 L0.415 Minimum X-ray luminosity at z=0.415 (1) 809-817 F9.5 fW/m2 L0.420 Minimum X-ray luminosity at z=0.420 (1) 819-827 F9.5 fW/m2 L0.425 Minimum X-ray luminosity at z=0.425 (1) 829-837 F9.5 fW/m2 L0.430 Minimum X-ray luminosity at z=0.430 (1) 839-847 F9.5 fW/m2 L0.435 Minimum X-ray luminosity at z=0.435 (1) 849-857 F9.5 fW/m2 L0.440 Minimum X-ray luminosity at z=0.440 (1) 859-867 F9.5 fW/m2 L0.445 Minimum X-ray luminosity at z=0.445 (1) 869-877 F9.5 fW/m2 L0.450 Minimum X-ray luminosity at z=0.450 (1) 879-887 F9.5 fW/m2 L0.455 Minimum X-ray luminosity at z=0.455 (1) 889-897 F9.5 fW/m2 L0.460 Minimum X-ray luminosity at z=0.460 (1) 899-907 F9.5 fW/m2 L0.465 Minimum X-ray luminosity at z=0.465 (1) 909-917 F9.5 fW/m2 L0.470 Minimum X-ray luminosity at z=0.470 (1) 919-927 F9.5 fW/m2 L0.475 Minimum X-ray luminosity at z=0.475 (1) 929-937 F9.5 fW/m2 L0.480 Minimum X-ray luminosity at z=0.480 (1) 939-947 F9.5 fW/m2 L0.485 Minimum X-ray luminosity at z=0.485 (1) 949-957 F9.5 fW/m2 L0.490 Minimum X-ray luminosity at z=0.490 (1) 959-967 F9.5 fW/m2 L0.495 Minimum X-ray luminosity at z=0.495 (1) 969-977 F9.5 fW/m2 L0.500 Minimum X-ray luminosity at z=0.500 (1) 979-987 F9.5 fW/m2 L0.505 Minimum X-ray luminosity at z=0.505 (1) 989-997 F9.5 fW/m2 L0.510 Minimum X-ray luminosity at z=0.510 (1) 999-1007 F9.5 fW/m2 L0.515 Minimum X-ray luminosity at z=0.515 (1) 1009-1017 F9.5 fW/m2 L0.520 Minimum X-ray luminosity at z=0.520 (1) 1019-1027 F9.5 fW/m2 L0.525 Minimum X-ray luminosity at z=0.525 (1) 1029-1038 F10.5 fW/m2 L0.530 Minimum X-ray luminosity at z=0.530 (1) 1040-1049 F10.5 fW/m2 L0.535 Minimum X-ray luminosity at z=0.535 (1) 1051-1060 F10.5 fW/m2 L0.540 Minimum X-ray luminosity at z=0.540 (1) 1062-1071 F10.5 fW/m2 L0.545 Minimum X-ray luminosity at z=0.545 (1) 1073-1082 F10.5 fW/m2 L0.550 Minimum X-ray luminosity at z=0.550 (1) 1084-1093 F10.5 fW/m2 L0.555 Minimum X-ray luminosity at z=0.555 (1) 1095-1104 F10.5 fW/m2 L0.560 Minimum X-ray luminosity at z=0.560 (1) 1106-1115 F10.5 fW/m2 L0.565 Minimum X-ray luminosity at z=0.565 (1) 1117-1126 F10.5 fW/m2 L0.570 Minimum X-ray luminosity at z=0.570 (1) 1128-1137 F10.5 fW/m2 L0.575 Minimum X-ray luminosity at z=0.575 (1) 1139-1148 F10.5 fW/m2 L0.580 Minimum X-ray luminosity at z=0.580 (1) 1150-1159 F10.5 fW/m2 L0.585 Minimum X-ray luminosity at z=0.585 (1) 1161-1170 F10.5 fW/m2 L0.590 Minimum X-ray luminosity at z=0.590 (1) 1172-1181 F10.5 fW/m2 L0.595 Minimum X-ray luminosity at z=0.595 (1) 1183-1192 F10.5 fW/m2 L0.600 Minimum X-ray luminosity at z=0.600 (1) 1194-1203 F10.5 fW/m2 L0.605 Minimum X-ray luminosity at z=0.605 (1) 1205-1214 F10.5 fW/m2 L0.610 Minimum X-ray luminosity at z=0.610 (1) 1216-1225 F10.5 fW/m2 L0.615 Minimum X-ray luminosity at z=0.615 (1) 1227-1236 F10.5 fW/m2 L0.620 Minimum X-ray luminosity at z=0.620 (1) 1238-1247 F10.5 fW/m2 L0.625 Minimum X-ray luminosity at z=0.625 (1) 1249-1258 F10.5 fW/m2 L0.630 Minimum X-ray luminosity at z=0.630 (1) 1260-1269 F10.5 fW/m2 L0.635 Minimum X-ray luminosity at z=0.635 (1) 1271-1280 F10.5 fW/m2 L0.640 Minimum X-ray luminosity at z=0.640 (1) 1282-1291 F10.5 fW/m2 L0.645 Minimum X-ray luminosity at z=0.645 (1) 1293-1302 F10.5 fW/m2 L0.650 Minimum X-ray luminosity at z=0.650 (1) 1304-1313 F10.5 fW/m2 L0.655 Minimum X-ray luminosity at z=0.655 (1) 1315-1324 F10.5 fW/m2 L0.660 Minimum X-ray luminosity at z=0.660 (1) 1326-1335 F10.5 fW/m2 L0.665 Minimum X-ray luminosity at z=0.665 (1) 1337-1346 F10.5 fW/m2 L0.670 Minimum X-ray luminosity at z=0.670 (1) 1348-1357 F10.5 fW/m2 L0.675 Minimum X-ray luminosity at z=0.675 (1) 1359-1368 F10.5 fW/m2 L0.680 Minimum X-ray luminosity at z=0.680 (1) 1370-1379 F10.5 fW/m2 L0.685 Minimum X-ray luminosity at z=0.685 (1) 1381-1390 F10.5 fW/m2 L0.690 Minimum X-ray luminosity at z=0.690 (1) 1392-1401 F10.5 fW/m2 L0.695 Minimum X-ray luminosity at z=0.695 (1) 1403-1412 F10.5 fW/m2 L0.700 Minimum X-ray luminosity at z=0.700 (1) 1414-1423 F10.5 fW/m2 L0.705 Minimum X-ray luminosity at z=0.705 (1) 1425-1434 F10.5 fW/m2 L0.710 Minimum X-ray luminosity at z=0.710 (1) 1436-1445 F10.5 fW/m2 L0.715 Minimum X-ray luminosity at z=0.715 (1) 1447-1456 F10.5 fW/m2 L0.720 Minimum X-ray luminosity at z=0.720 (1) 1458-1467 F10.5 fW/m2 L0.725 Minimum X-ray luminosity at z=0.725 (1) 1469-1478 F10.5 fW/m2 L0.730 Minimum X-ray luminosity at z=0.730 (1) 1480-1489 F10.5 fW/m2 L0.735 Minimum X-ray luminosity at z=0.735 (1) 1491-1500 F10.5 fW/m2 L0.740 Minimum X-ray luminosity at z=0.740 (1) 1502-1511 F10.5 fW/m2 L0.745 Minimum X-ray luminosity at z=0.745 (1) 1513-1522 F10.5 fW/m2 L0.750 Minimum X-ray luminosity at z=0.750 (1) 1524-1533 F10.5 fW/m2 L0.755 Minimum X-ray luminosity at z=0.755 (1) 1535-1544 F10.5 fW/m2 L0.760 Minimum X-ray luminosity at z=0.760 (1) 1546-1555 F10.5 fW/m2 L0.765 Minimum X-ray luminosity at z=0.765 (1) 1557-1566 F10.5 fW/m2 L0.770 Minimum X-ray luminosity at z=0.770 (1) 1568-1577 F10.5 fW/m2 L0.775 Minimum X-ray luminosity at z=0.775 (1) 1579-1588 F10.5 fW/m2 L0.780 Minimum X-ray luminosity at z=0.780 (1) 1590-1599 F10.5 fW/m2 L0.785 Minimum X-ray luminosity at z=0.785 (1) 1601-1610 F10.5 fW/m2 L0.790 Minimum X-ray luminosity at z=0.790 (1) 1612-1621 F10.5 fW/m2 L0.795 Minimum X-ray luminosity at z=0.795 (1) 1623-1632 F10.5 fW/m2 L0.800 Minimum X-ray luminosity at z=0.800 (1)
Note (1): To be detected with 20 source photons. In the 0.1-2.4keV band and in units of 10-12erg/s/cm2.
History: From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 11-Aug-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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