Optical counterparts of two ULXs in NGC 5474 and NGC 3627 (M 66)

被引:12
作者
Avdan, S. [1 ,2 ]
Vinokurov, A. [3 ]
Fabrika, S. [3 ,4 ]
Atapin, K. [3 ,5 ]
Avdan, H. [1 ,2 ]
Akyuz, A. [1 ,2 ]
Sholukhova, O. [3 ]
Aksaker, N. [2 ,6 ]
Valeev, A. [3 ,4 ]
机构
[1] Cukurova Univ, Dept Phys, TR-01330 Adana, Turkey
[2] Cukurova Univ, Space Sci & Solar Energy Res & Applicat Ctr UZAYM, TR-01330 Adana, Turkey
[3] Special Astrophys Observ Russian AS, Nizhnii Arkhyz 369167, Russia
[4] Kazan Fed Univ, Kazan 420008, Russia
[5] Moscow MV Lomonosov State Univ, Sternberg Astron Inst, Moscow 119991, Russia
[6] Cukurova Univ, Vocat Sch Tech Sci, TR-01410 Adana, Turkey
关键词
galaxies:; individual:; NGC; 5474; 3627; X-rays: general; X-RAY SOURCES; SUPERCRITICAL ACCRETION DISKS; MASSIVE BLACK-HOLES; YOUNG STAR-CLUSTERS; SS; 433; ULTRALUMINOUS STATE; RUNAWAY COLLISIONS; GALAXIES; ENVIRONMENT; RADIATION;
D O I
10.1093/mnrasl/slv155
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We identified two optical counterparts of brightest ultraluminous X-ray sources (ULXs) in galaxies NGC 5474 and NGC 3627 (M66). The counterparts in Hubble Space Telescope images are very faint, their V magnitudes are 24.7 (M-V approximate to -4.5) and 25.9 (M-V approximate to -4.2), respectively. NGC 5474 X-1 changes the X-ray flux more than two orders of magnitude, in its bright state it has L-X approximate to 1.6 x 10(40) erg s(-1), the spectrum is best fitted by an absorbed power law model with a photon index Gamma approximate to 0.94. M66 X-1 varies in X-rays with a factor of similar to 2.5, its maximal luminosity being 2.0 x 10(40) erg s(-1) with Gamma approximate to 1.7. Optical spectroscopy of the NGC 5474 X-1 has shown a blue spectrum, which however was contaminated by a nearby star of 23 mag, but the counterpart has a redder spectrum. Among other objects captured by the slit are a background emission-line galaxy (z = 0.359) and a new young cluster of NGC 5474. We find that these two ULXs have largest X-ray-to-optical ratios of L-X/L-opt similar to 7000 for NGC 5474 X-1 (in its bright state) and 8000 for M66 X-1 both with the faintest optical counterparts ever measured. Probably their optical emission originates from the donor star. If they have super-Eddington accretion discs with stellar-mass black holes, they may also have the lowest mass accretion rates among ULXs such as in M81 X-6 and NGC 1313 X-1.
引用
收藏
页码:L91 / L95
页数:5
相关论文
共 39 条
[1]   Spectroscopy of Optical Counterparts of Ultraluminous X-Ray Sources [J].
Abolmasov, P. ;
Fabrika, S. ;
Sholukhova, O. ;
Afanasiev, V. .
ASTROPHYSICAL BULLETIN, 2007, 62 (01) :36-51
[2]   Optical spectroscopy of the environment of a ULX in NGC 7331 [J].
Abolmasov, Pavel K. ;
Swartz, Douglas A. ;
Fabrika, S. ;
Ghosh, Kajal K. ;
Sholukhova, O. ;
Tennant, Allyn F. .
ASTROPHYSICAL JOURNAL, 2007, 668 (01) :124-129
[3]   The SCORPIO universal focal reducer of the 6-m telescope [J].
Afanasiev, VL ;
Moiseev, AV .
ASTRONOMY LETTERS-A JOURNAL OF ASTRONOMY AND SPACE ASTROPHYSICS, 2005, 31 (03) :194-204
[4]   The evolution of the hard X-ray luminosity function of AGN [J].
Aird, J. ;
Nandra, K. ;
Laird, E. S. ;
Georgakakis, A. ;
Ashby, M. L. N. ;
Barmby, P. ;
Coil, A. L. ;
Huang, J. -S. ;
Koekemoer, A. M. ;
Steidel, C. C. ;
Willmer, C. N. A. .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2010, 401 (04) :2531-2551
[5]   X-ray reflection in a sample of X-ray bright ultraluminous X-ray sources [J].
Caballero-Garcia, M. D. ;
Fabian, A. C. .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2010, 402 (04) :2559-2566
[6]   The nature of accreting black holes in nearby galaxy nuclei [J].
Colbert, EJM ;
Mushotzky, RF .
ASTROPHYSICAL JOURNAL, 1999, 519 (01) :89-107
[7]  
Della C, 2015, MNRAS, V447, P3227
[8]   Photometric distances to six bright resolved galaxies [J].
Drozdovsky, IO ;
Karachentsev, ID .
ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES, 2000, 142 (03) :425-432
[9]  
Fabrika S., 2004, Astrophys. and Space Phys. Rev., V12, P1
[10]  
Fabrika S, 2015, NAT PHYS, V11, P551, DOI [10.1038/nphys3348, 10.1038/NPHYS3348]