| Article in PDF |
"Peremennye Zvezdy", Prilozhenie, vol. 17, N 1 (2017) |
| #1. Bundesdeutsche Arbeitsgemeinschaft fuer Veraenderliche Sterne e.V. (BAV), Berlin,
Germany;
#2. Linz, Austria; #3. Braubach, Germany; |
| ISSN 2221–0474 |
Received: 9.05.2014; accepted: 26.01.2017
(E-mail for contact: klaus.bernhard@liwest.at , ernham@rz-online.de)
|
Comments:
1. J–K = 0.686 (2MASS), 1RXS J001859.8+061937, HR1 = 0.24, HR2 = 0.24, probably quasar (Flesch 2010); SDSS, Release 9: star-like object; CSS light curve: very slow variations, confirmed as quasar.
2. J–K = 1.412 (2MASS), 1RXS J003059.3–115300, HR1 = –0.41, HR2 = 0.33, 6dF J0030580–115306, z = 0.240540 (Jones, Read, Saunders et al. 2009), AGN candidate (Kouzuma and Yamaoka 2010); CSS light curve: slow variations, possible period ~2200 d, confirmed as quasar.
3. J–K = 1.728 (2MASS), 1RXS J015948.9–035206, HR1 = –0.51, HR2 = 0.00, probably quasar (Flesch 2010), AGN candidate (Kouzuma and Yamaoka, 2010); SDSS, Release 9: star-like object; CSS light curve: slow, irregular variations, confirmed as quasar.
4. J–K = 1.32 (2MASS), 1RXS J022218.0–062513, HR1 = –0.40, HR2 = –0.16, probably quasar (Flesch 2010), AGN candidate (Kouzuma and Yamaoka 2010); SDSS, Release 9: star-like object; CSS light curve: very slow variations, confirmed as quasar.
5. J–K = 1.74 (2MASS), 1RXS J070344.4+510040, HR1 = 0.60, HR2 = –0.28, probably quasar (Flesch 2010); CSS light curve: very slow variations, confirmed as quasar.
6. J–K = 1.493 (2MASS), 1RXS J071136.5+241124, HR1 = 0.66, HR2 = –0.27, AGN candidate (Kouzuma and Yamaoka 2010); CSS light curve: very slow variations, confirmed as quasar.
7. J–K = 1.512 (2MASS), 1RXS J073806.9+212726, HR1 = 0.13, HR2 = –0.49, probably quasar (Flesch 2010; Abraham, Philip, Kembhavi et al. 2012), AGN candidate (Kouzuma and Yamaoka 2010); SDSS, Release 9: star-like object; CSS light curve: very slow variations, confirmed as quasar.
8. J–K = 1.616 (2MASS), 1RXS J074240.3+354023, HR1 = 0.38, HR2 = –0.07, probably quasar (Flesch 2010), AGN candidate (Kouzuma and Yamaoka 2010); SDSS, Release 9: star-like object; CSS light curve: slow, irregular variations, confirmed as quasar.
9. J–K = 0.542 (2MASS), 1RXS J082904.3+074335, HR1 = 0.54, HR2 = 0.61, probably quasar (Flesch 2010); SDSS, Release 9: star-like object; CSS light curve: slow variations, possible period ~1550 d, confirmed as quasar.
10. J–K = 1.661 (2MASS), 1RXS J085429.8–070046, HR1 = 0.57, HR2 = 0.20, probably quasar (Flesch 2010); CSS light curve: slow, irregular variations, confirmed as quasar.
11. J–K = 1.753 (2MASS), 1RXS J090553.8–042608, HR1 = –0.21, HR2 = 0.14, probably quasar (Flesch 2010), AGN candidate (Kouzuma and Yamaoka 2010); CSS light curve: slow, irregular variations, confirmed as quasar.
12. J–K = 1.579 (2MASS), 1RXS J093322.7–293956, HR1 = 0.80, HR2 = 0.13, AGN candidate (Kouzuma and Yamaoka 2010); CSS light curve: slow, irregular variations, confirmed as quasar.
13. J–K = 1.768 (2MASS), 1RXS J105038.2+170220, HR1 = 0.33, HR2 = 0.28, quasar or Seyfert galaxy (Flesch 2010), AGN candidate (Kouzuma and Yamaoka 2010), Probably Sab or Scd galaxy (Huertas-Company, Aguerri, Bernardi et al., 2011); SDSS Release 9: galaxy; CSS light curve: irregular variations, confirmed as Seyfert 1 galaxy.
14. J–K = 0.784 (2MASS), 1RXS J114142.4–023248, HR1 = 0.44, HR2 = 0.38, quasar candidate, SDSS J114142.22–023253.4, z = 0.325 (Richards, Nichol, Gray et al. 2004); SDSS, Release 9: star-like object; CSS light curve: slow, irregular variations, confirmed as quasar.
15. J–K = 1.569 (2MASS), 1RXS J140319.7–264417, HR1 = 0.53, HR2 = –0.01, quasar or Seyfert galaxy (Flesch 2010), AGN candidate (Kouzuma and Yamaoka 2010); CSS light curve: slow, irregular variations, confirmed as quasar.
16. J–K = 1.328 (2MASS), 1RXS J154426.3–201637, HR1 = 0.84, HR2 = 0.27, AGN candidate (Kouzuma and Yamaoka 2010), SDSS, Release 9: star-like object; CSS light curve: slow, irregular variations, confirmed as quasar.
17. J–K = 1.81 (2MASS), 1RXS J165939.3+510717, HR1 = 0.01, HR2 = 0.50, probably quasar (Flesch 2010), AGN candidate (Kouzuma and Yamaoka 2010); CSS light curve: slow, irregular variations, confirmed as quasar.
18. J–K = 1.426 (2MASS), 1RXS J172529.7+380445, HR1 = 0.07, HR2 = –0.19, probably quasar (Flesch 2010), AGN candidate (Kouzuma and Yamaoka 2010); SDSS, Release 9: star-like object; CSS light curve: slow, irregular variations, confirmed as quasar.
19. J–K = 1.337 (2MASS), 1RXS J173757.0+343256, HR1 = –0.22, HR2 = –0.18, AGN candidate (Kouzuma and Yamaoka 2010); CSS light curve: very slow variations, confirmed as quasar.
20. J–K = 0.85 (2MASS), 1RXS J205155.5–233651, HR1 = –0.70, HR2 = 0.31; CSS light curve: slow, irregular variations, confirmed as quasar.
21. J–K = 1.423 (2MASS), 1RXS J210210.0–092914, HR1 = 0.10, HR2 = 0.18, 2MASX J21021062–0929048, type galaxy, AGN candidate (Kouzuma and Yamaoka 2010); CSS light curve: very slow variations, confirmed as quasar.
22. J–K = 0.979 (2MASS), 1RXS J210421.1–021233, HR1 = 0.71, HR2 = –0.20; SDSS, Release 9: star-like object; CSS light curve: slow, irregular variations, confirmed as quasar.
23. J–K = 1.688 (2MASS), 1RXS J215602.5+181839, HR1 = 0.67, HR2 = –0.04, GALEX 2665614247650660913 (quasar candidate), probably quasar (Flesch 2010), AGN candidate (Kouzuma and Yamaoka 2010); SDSS, Release 9: star-like object; CSS light curve: slow, irregular variations, confirmed as quasar.
24. J–K = 1.443 (2MASS), 1RXS J215727.0–061022, HR1 = 0.08, HR2 = 0.67, quasar or Seyfert galaxy (Flesch 2010); SDSS, Release 9: star-like object; CSS light curve: slow, irregular variations, confirmed as quasar.
25. J–K = 1.453 (2MASS), 1RXS J223732.3–033805, HR1 = 0.47, HR2 = 0.90, AGN candidate (Kouzuma and Yamaoka 2010); SDSS, Release 9: star-like object; CSS light curve: slow, irregular variations, confirmed as quasar.
26. J–K = 0.475 (2MASS), 1RXS J233915.2-225752, HR1 = –0.31, HR2 = –0.20, 6dF J2339155–225758, z = 0.834777, type: galaxy (Mahony, Croom, Boyle et al. 2010), probably quasar (Flesch 2010); CSS light curve: slow, irregular variations, confirmed as quasarRemarks:
We present Catalina Sky Survey (CSS, Drake et al. 2009) light curves of 26 variable optical counterparts to selected sources from the ROSAT All-Sky Survey Bright Source Catalogue (Voges, Aschenbach, Boller et al. 1999), which can be identified with candidate active galactic nuclei (AGNs) from various catalogues (eg. Kouzuma and Yamaoka 2010). The sample of possible AGNs comprises of 25 likely quasars and one likely Seyfert type 1 galaxy (= No. 13, 2MASS J10503791+1702084). We confirm their AGN nature in this work on grounds of their typical photometric variability (cf. e.g. Bauer, Baltay, Coppi et al. 2009) and their X-ray identification.
Each object was checked against the Strasbourg CDS Vizier and SIMBAD services and the NASA/IPAC Extragalactic Database for information about its nature and known optical variability. Astrometric positions were derived from the 2MASS catalogue (Skrutskie, Cutri, Stiening et al. 2006). Near-infrared colour indices from the 2MASS catalog and ROSAT All-Sky Survey Bright Source Catalogue identifications are presented in the comments. Whenever available, the source classification of the object ("Star" or "Galaxy"), which provides valuable information to distinguish star-like quasars from extended Seyfert galaxies, was derived from Data Release 9 of the SDSS Photometric Catalog (Ahn, Alexandroff, Allende Prieto et al. 2012) and included in the analysis.
We have carried out period analyses of all objects with Period04 (Lenz and Breger 2005), which reveal that the light variations of the 26 AGNs are mostly slow and irregular without any clear periodicity (17 objects). We find possible semiregular variations in two quasars (2MASS 00305804–1153059, P ~2200 d and 2MASS 08290463+0743391, P ~1550 d). However, because of the length of the periods and the comparably short time baseline of about seven years, we stress the preliminary and uncertain nature of these results, which need to be confirmed by further, long-term photometric studies. It is interesting to note, though, that similar long-period variations of AGNs are proposed in the literature (cf. e.g. Bisch, Pastoriza, Dottori, Busko 1987; Cid Fernandes, Terlevich, Aretxaga et al. 1997; Oknyanskij and Lyuty 2007).
Seven quasars vary on very long timescales during the observed timespan. For these objects, we were not able to decide between periodic or irregular behaviour because of an insufficient time baseline. The corresponding quasars were tagged with "very slow variations" in the remarks. The observed, mostly irregular variations of the quasars and the Seyfert galaxy are in line with observational evidence presented in other publications (e.g. Vanden Berk, Wilhite, Kron et al., 2004; Cioni, Kamath, Rubele et al., 2012).
Acknowledgements: This publication has made use of the SIMBAD and VizieR databases operated at the Centre de Données Astronomiques (Strasbourg) in France, of the NASA/IPAC Extragalactic Database (NED), of the Sloan Digital Sky Survey (SDSS) and of the Two Micron All Sky Survey (2MASS), which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation.References:
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