NGC 3115 Chandra X-Ray Point Source Catalog

NGC 3115 Chandra X-Ray Point Source Catalog NGC3115CXO ivo://nasa.heasarc/ngc3115cxo NASA/GSFC HEASARC Lin et al. 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source This table contains some of the results from an in-depth study of low-mass X-ray binaries (LMXBs) detected in the nearby lenticular galaxy NGC 3115 using the Megasecond Chandra X-ray Visionary Project observation (total exposure time 1.1 Ms). In total the authors found 136 candidate LMXBs in the field and 49 in globular clusters (GCs) above 2-sigma detection, with 0.3-8 keV luminosity LX ~ 1036 - 1039 erg s-1. Other than 13 transient candidates, the sources overall have less long-term variability at higher luminosity, at least at LX >~ 2 x 1037 erg s-1. In order to identify the nature and spectral state of these sources, the authors compared their collective spectral properties based on single-component models (a simple power law or a multicolor disk) with the spectral evolution seen in representative Galactic LMXBs. The authors found that in the LX vs. photon index GammaPL and LX versus disk temperature kTMCD plots, most of their sources fall on a narrow track in which the spectral shape hardens with increasing luminosity below LX ~ 7 x 1037 erg s-1, but is relatively constant (GammaPL ~ 1.5 or kTMCD ~ 1.5 keV) above this luminosity, which is similar to the spectral evolution of Galactic neutron star (NS) LMXBs in the soft state in the Chandra bandpass. Therefore, the authors identified the track as the NS LMXB soft-state track and suggested sources with LX <~ 1037 erg s-1 as atolls in the soft state and those with LX >~ 1037 erg s-1 as Z sources. Ten other sources (five are transients) displayed significantly softer spectra and are probably black hole X-ray binaries in the thermal state. One of them (a persistent source) is in a metal-poor GC. The 11 Chandra observations of NGC 3115 are listed in Table 1 of the reference paper. They were made during three epochs: one in 2001,two in 2010, and nine in 2012. All observations used the imaging array of the AXAF CCD Imaging Spectrometer (ACIS). This table contains the properties of the 482 detected point sources in the merged and single Chandra ACIS observations of NGC 3115 above a 2-sigma threshold and after eliminating a number of spurious sources associated with bright streaks on the ACIS-S1 chip and (in one case) on a CCD edge. 469 of these sources (indicated by values of obs_flag = '0') have a single entry in this table, based on their properties as derived from all of the available Chandra data for that position. There are 13 transient sources (having obs_flag = 'h') for which an additional entry is provided referring to their properties in the "high state", and based on the combination of their high-state observations, as shown in Figures 3(a) - 3(d) in the reference paper. For source number 198, there is a second additional entry provided referring to its properties in the "low state", and based on the combination of its low-state observations, as shown in Figure 3(c) in the reference paper. Thus, there are 496 entries (rows) in this table, i.e., 482 + 13 + 1. This table was created by the HEASARC in August 2015 based on the union of the machine-readable versions of Table 3 (the master source catalog) and Table 4 (the source counts, fluxes and hardness ratios in the merged observations) that were obtained from the ApJ web site. It does not contain the source counts and fluxes in the individual observations which were given in Table 5 of the reference paper. This is a service provided by NASA HEASARC . 2015ApJ...808...19L https://heasarc.gsfc.nasa.gov/W3Browse/all/ngc3115cxo.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=ngc3115cxo& GET text/xml 180 99999 true 151.499405 -8.028296 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=ngc3115cxo GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_ngc3115cxo&Action=More+Options&Action=Parameter+Search&ConeAdd=1 CHANDRA 0.0166666666666667 X-ray public ngc3115cxo NGC 3115 Chandra X-Ray Point Source Catalog source_number Sequential Identification Number for Each Source in Catalog meta.id;src short nullable name CXOU Source Designation meta.id;meta.main char nullable ra Right Ascension degree pos.eq.ra;meta.main double nullable dec Declination degree pos.eq.dec;meta.main double nullable error_radius The 1-Sigma Statistical Positional Uncertainty in Each Coordinate arcsec stat.error;pos double nullable lx_bb_min Minimum 0.5-7 keV Luminosity erg/s phys.luminosity;em.X-ray;stat.min double nullable lx_bb_min_neg_err Negative Error on Lmin at 68% Confidence Level erg/s stat.error;phys.luminosity;em.X-ray;stat.min double nullable lx_bb_min_pos_err Positive Error of Lmin at 68% Confidence Level erg/s stat.error;phys.luminosity;em.X-ray;stat.min double nullable lx_bb_max Maximum 0.5-7 keV Luminosity erg/s phys.luminosity;em.X-ray;stat.max double nullable lx_bb_max_neg_err Negative Error on Lmax at 68% Confidence Level erg/s stat.error;phys.luminosity;em.X-ray;stat.max double nullable lx_bb_max_pos_err Positive Error of Lmax at 68% Confidence Level erg/s stat.error;phys.luminosity;em.X-ray;stat.max double nullable source_type Source Type src.class char nullable "__x_ra_dec" System unit vector column double nullable "__y_ra_dec" System unit vector column double nullable "__z_ra_dec" System unit vector column double nullable "__row" System index column char nullable hb_flux_neg_err Negative Error of Hard-Band Flux at 68% Confidence Level erg/s/cm^2 stat.error;phot.flux;em.X-ray.medium double nullable hardness_ratio_1_pos_err Positive Error of HR1 at 68% Confidence Level stat.error;phot.flux;arith.ratio;em.X-ray.soft double nullable lii Galactic Longitude degree pos.galactic.lon double nullable obs_flag Flag [hl0] Indicates Type of Observation: h=High State, l=Low State, 0=Merged meta.code;obs char nullable mb_counts_neg_err Negative Error of Medium-Band Counts at 68% Confidence Level stat.error;phot;em.X-ray.soft double nullable hardness_ratio_2 Hardness Ratio (2) Using the 1.2-2.0 keV and the 2.0-7.0 keV Fluxes phot.flux;arith.ratio;em.X-ray double nullable sb_counts_pos_err Positive Error of Soft-Band Counts at 68% Confidence Level stat.error;phot;em.X-ray.soft double nullable bb_snr Signal-to-Noise Ratio stat.snr;phot;em.X-ray double nullable usb_flux_pos_err Positive Error of Ultra-Soft Flux at 68% Confidence Level erg/s/cm^2 stat.error;phot.flux;em.X-ray.soft double nullable sb_counts Counts in the Soft Band; 0.5-1.2 keV phot;em.X-ray.soft double nullable hb_flux Flux in the Hard Band; 2.0-7.0 KeV erg/s/cm^2 phot.flux;em.X-ray.medium double nullable obsid_min Corresponding Observation Identification of Minimum 0.5-7 keV Luminosity meta.id;obs char nullable mb_counts Counts in the Medium Band; 1.2-2.0 keV phot;em.X-ray.soft double nullable bb_flux_neg_err Negative Error of Broad-Band Flux at 68% Confidence Level erg/s/cm^2 stat.error;phot.flux;em.X-ray double nullable usb_counts_pos_err Positive Error of Ultra-Soft Counts at 68% Confidence Level stat.error;phot;em.X-ray.soft double nullable mb_flux_neg_err Negative Error of Medium-Band Flux at 68% Confidence Level erg/s/cm^2 stat.error;phot.flux;em.X-ray.soft double nullable hb_counts_neg_err Negative Error of Hard-Band Counts at 68% Confidence Level stat.error;phot;em.X-ray.medium double nullable short_term_var_index Maximum Gregory-Loredo Short-Term Variability Index src.var.index;em.X-ray short nullable class Browse Object Classification src.class short nullable bb_counts_pos_err Positive Error of Broad-Band Counts at 68% Confidence Level stat.error;phot;em.X-ray double nullable usb_flux_neg_err Negative Error of Ultra-Soft Flux at 68% Confidence Level erg/s/cm^2 stat.error;phot.flux;em.X-ray.soft double nullable sb_counts_neg_err Negative Error of Soft-Band Counts at 68% Confidence Level stat.error;phot;em.X-ray.soft double nullable hb_counts Counts in the Hard Band; 2.0-7.0 keV phot;em.X-ray.medium double nullable obsid Observation Identification in Which the Source Is Detected meta.id;obs char nullable bb_flux_pos_err Positive Error of Broad-Band Flux at 68% Confidence Level erg/s/cm^2 stat.error;phot.flux;em.X-ray double nullable usb_counts_neg_err Negative Error of Ultra-Soft Counts at 68% Confidence Level stat.error;phot;em.X-ray.soft double nullable scaled_radius Ratio of Angular Separation to D25 Isophote Elliptical Radius pos.angDistance;arith.ratio double nullable angular_radius Angular Separation from Galaxy Center arcmin pos.angDistance double nullable mb_flux_pos_err Positive Error of Medium-Band Flux at 68% Confidence Level erg/s/cm^2 stat.error;phot.flux;em.X-ray.soft double nullable sb_flux Flux in the Soft Band; 0.5-1.2 keV erg/s/cm^2 phot.flux;em.X-ray.soft double nullable hardness_ratio_3_neg_err Negative Error of HR3 at 68% Confidence Level stat.error;phot.flux;arith.ratio;em.X-ray double nullable psf_90pc_radius The 90% PSF Radius at the Source Position in Merged Observation arcsec instr.det.psf double nullable bb_counts_neg_err Negative Error of Broad-Band Counts at 68% Confidence Level stat.error;phot;em.X-ray double nullable mb_counts_pos_err Positive Error of Medium-Band Counts at 68% Confidence Level stat.error;phot;em.X-ray.soft double nullable long_term_var_factor Flux Variation Factor in 0.5-7 keV Band src.var.amplitude;em.X-ray double nullable sb_flux_neg_err Negative Error of Soft-Band Flux at 68% Confidence Level erg/s/cm^2 stat.error;phot.flux;em.X-ray.soft double nullable bb_counts Counts in the Broad Band; 0.5-7.0 keV phot;em.X-ray double nullable long_term_var_sig Significance of Flux Variation; Equation 1 stat.likelihood;src.var;em.X-ray double nullable hardness_ratio_2_neg_err Negative Error of HR2 at 68% Confidence Level stat.error;phot.flux;arith.ratio;em.X-ray double nullable exposure Exposure Time s time.duration;obs.exposure double nullable usb_flux Flux in the Ultra-Soft Band; 0.2-0.5 keV erg/s/cm^2 phot.flux;em.X-ray.soft double nullable mb_flux Flux in the Medium Band; 1.2-2.0 keV erg/s/cm^2 phot.flux;em.X-ray.soft double nullable hardness_ratio_1 Hardness Ratio (1) Using the 0.5-1.2 keV and the 1.2-2.0 keV Fluxes phot.flux;arith.ratio;em.X-ray.soft double nullable bb_flux Flux in the Broad Band; 0.5-7.0 keV erg/s/cm^2 phot.flux;em.X-ray double nullable hb_counts_pos_err Positive Error of Hard-Band Counts at 68% Confidence Level stat.error;phot;em.X-ray.medium double nullable usb_counts Counts in the Ultra-Soft Band; 0.2-0.5 keV phot;em.X-ray.soft double nullable psf_50pc_radius The 50% PSF Radius at the Source Position in Merged Observation arcsec instr.det.psf double nullable hardness_ratio_3_pos_err Positive Error of HR3 at 68% Confidence Level stat.error;phot.flux;arith.ratio;em.X-ray double nullable sb_flux_pos_err Positive Error of Soft-Band Flux at 68% Confidence Level erg/s/cm^2 stat.error;phot.flux;em.X-ray.soft double nullable hb_flux_pos_err Positive Error of Hard-Band Flux at 68% Confidence Level erg/s/cm^2 stat.error;phot.flux;em.X-ray.medium double nullable hardness_ratio_3 Hardness Ratio (3) Using the 0.5-2.0 keV and the 2.0-7.0 keV Fluxes phot.flux;arith.ratio;em.X-ray double nullable bii Galactic Latitude degree pos.galactic.lat double nullable hardness_ratio_2_pos_err Positive Error of HR2 at 68% Confidence Level stat.error;phot.flux;arith.ratio;em.X-ray double nullable obsid_max Corresponding Observation Identification of Maximum 0.5-7 keV Luminosity meta.id;obs char nullable hardness_ratio_1_neg_err Negative Error of HR1 at 68% Confidence Level stat.error;phot.flux;arith.ratio;em.X-ray.soft double nullable