* Astronomy

Members Login
Username 
 
Password 
    Remember Me  
Home -> Astronomy News -> Astronomy News -> Ultraluminous X-ray sources
Post Info TOPIC: Ultraluminous X-ray sources
Blobrana


L

Posts: 131433
Date:
RE: Ultraluminous X-ray sources
Permalink  
 

Title: Accurate positions for the ULXs NGC 7319-X4 and NGC 5474-X1 and limiting magnitudes for their optical counterparts
Authors: M. Heida, P. G. Jonker, M. A. P. Torres, S. Mineo

In this paper we report accurate Chandra positions for two ultraluminous X-ray sources: NGC 7319-X4 at Right Ascension (RA) = 339.02917(2) deg, Declination (Dec) = 33.97476(2) deg and NGC 5474-X1 at RA = 211.24859(3) deg, Dec = 53.63584(3) deg. We perform bore-sight corrections on the Chandra X-ray Satellite observations of these sources to get to these accurate positions of the X-ray sources and match these positions with archival optical data from the Wide Field and Planetary Camera 2 on board the Hubble Space Telescope. We do not find the optical counterparts: the limiting absolute magnitudes of the observations in the WFPC2 standard magnitude system are B = -7.9, V = -8.7 and I = -9.3 for NGC 7319-X4 and U = -6.4 for NGC 5474-X1. We report on the X-ray spectral properties and we find evidence for X-ray variability in NGC 5474-X1. Finally, we briefly discuss several options for the nature of these ULXs.

Read more (1296kb, PDF)



__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

Title: New Hubble Space Telescope imaging of the counterparts to six ultraluminous X-ray sources
Authors: T. P. Roberts (1), A. J. Levan (2), M. R. Goad (3) ((1) Durham University, (2) University of Warwick, (3) University of Leicester)

We report the results of new Hubble Space Telescope imaging of the positions of six ultraluminous X-ray sources (ULXs). Using images in three ACS filters we detect good candidate counterparts to four out of six ULXs, with one more possible detection, and observed magnitudes in the range m ~ 22 - 26 in the F606W filter. The extinction-corrected colours and absolute magnitudes vary from source to source, even after correcting for additional extinction in the host galaxy, and only one counterpart is readily explained as an OB star. Nevertheless, these counterparts are decent candidates for future follow-up in pursuit of dynamical mass constraints on the likely black holes powering these sources.

Read more (282kb, PDF)
Read more ( PDF)

__________________
Page 1 of 1  sorted by
Quick Reply

Please log in to post quick replies.
Home -> Astronomy News -> Astronomy News -> Ultraluminous X-ray sources


Create your own FREE Forum
Report Abuse 		Powered by ActiveBoard