We present Chandra observation of the nearby spiral galaxy NGC 1559 to study the X-ray sources population in the galaxy. Based on our analysis, we detect twenty-four X-ray sources in the galaxy, of which six have 0.5-8 keV luminosities exceeding 10 39 erg s -1 , suggesting that they are possibly ultra-luminous X-ray source (ULX) candidates. The remaining eighteen sources have 0.5-8 keV luminosities below this threshold value, suggesting that they are likely to be X-ray binary candidates. We perform X-ray spectral analysis for the six ULX candidates and found that in general, their properties are broadly consistent with that found for other ULXs. The number of X-ray sources found in this galaxy is relatively high as compared to other galaxies with similar star formation rate of ~2.8 Myr -1 . This however could be attributed to the relatively high number of supernova occurrence (four) in the galaxy observed in the past years. We did not detect any X-ray nuclear point source in the galaxy, suggesting that NGC 1559 does not host an active galactic nucleus. This is supported by its HII optical spectral classification and our infrared analysis using WISE.

We present Chandra observation of the nearby spiral galaxy NGC 1559 to study the X-ray sources population in the galaxy. Based on our analysis, we detect twenty-four X-ray sources in the galaxy, of which six have 0.5–8 keV luminosities exceeding 10³⁹ erg s^-1, suggesting that they are possibly ultra-luminous X-ray source (ULX) candidates. The remaining eighteen sources have 0.5–8 keV luminosities below this threshold value, suggesting that they are likely to be X-ray binary candidates. We perform X-ray spectral analysis for the six ULX candidates and found that in general, their properties are broadly consistent with that found for other ULXs. The number of X-ray sources found in this galaxy is relatively high as compared to other galaxies with similar star formation rate of ~2.8 M- yr^-1. This however could be attributed to the relatively high number of supernova occurrence (four) in the galaxy observed in the past years. We did not detect any X-ray nuclear point source in the galaxy, suggesting that NGC 1559 does not host an active galactic nucleus. This is supported by its HII optical spectral classification and our infrared analysis using WISE.

We present Chandra observations of the nearby polar ring galaxy NGC 660 to study its X-ray source population. Based on our analysis, we detected a total of 23 X-ray sources in the 0.5−8 keV band, with luminosities ranging from ∼1037 to ∼1039 erg s−1. Twenty-two of these sources are located off-nuclear and have luminosities below the ultraluminous X-ray source (ULX) threshold value of L 0.5−8 keV < 1039 erg s−1, suggesting that they are likely to be X-ray binary (XRB) candidates. The remaining source is located at the center of the galaxy, suggesting it is an active galactic nucleus (AGN). However, we estimated that four of the detected sources could be associated with background objects. Based on the source count rates in each of the Chandra observations, we found evidence for variability in nine of the 23 sources, including the AGN. However, further investigation with spectral analysis suggested no significant differences in the AGN luminosities between the observations. The X-ray luminosity distribution of the galaxy was found to be generally lower than that expected from previous studies on star forming and collisional ring galaxies. No ULX was also detected in the galaxy, in contrast with what was expected from the galaxyʼs SFR and metallicity (i.e., SFR = 14.43 ± 0.19 M ⊙ yr−1 and Z = 0.94 ± 0.01 Z ⊙, respectively). These results suggest a deficit in the X-ray sources detected. Based on source hardness ratio distribution, we found evidence that the fainter sources have a harder source spectrum, indicating higher absorption. This further suggests that there could be more X-ray sources that were not detected in the galaxy due to significant obscuration.