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25191. X-ray-selected normal galaxies
ID:
ivo://CDS.VizieR/J/MNRAS/360/782
Title:
X-ray-selected normal galaxies
Short Name:
J/MNRAS/360/782
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this paper we estimate the local (z<0.22) X-ray luminosity function of 'normal' galaxies derived from the XMM-Newton Needles in the Haystack Survey. This is an on-going project that aims to identify X-ray-selected normal galaxies (i.e. non-AGN dominated) in the local Universe. We are using a total of 70 XMM-Newton fields covering an area of 11deg^2^ which overlap with the Sloan Digital Sky Survey Data Release 2. Normal galaxies are selected on the basis of their resolved optical light profile, their low X-ray-to-optical flux ratio [log(fx/fo)<-2] and soft X-ray colours. We find a total of 28 candidate normal galaxies to the 0.58keV band flux limit of 2x10^-15^erg/cm2/s. Optical spectra are available for most sources in our sample (82 per cent). These provide additional evidence that our sources are bona fide normal galaxies with X-ray emission coming from diffuse hot gas emission and/or X-ray binaries rather than a supermassive black hole.
25192. X-ray selected ROSAT AGN spectra
ID:
ivo://CDS.VizieR/J/A+A/350/805
Title:
X-ray selected ROSAT AGN spectra
Short Name:
J/A+A/350/805
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the emission line properties of a sample of 76 bright soft X-ray selected ROSAT Active Galactic Nuclei. All optical counterparts are Seyfert 1 galaxies with rather narrow permitted lines, strong optical FeII line blends, and weak forbidden lines. By selection, they also have steep soft X-ray spectra when compared with typical Seyfert 1 galaxies. We discuss possible origins of these peculiar trends employing detailed correlation analyses, including a Principal Component Analysis. The optical spectra are presented in the Appendix.
25193. X-rays from HH 80/81 complex
ID:
ivo://CDS.VizieR/J/ApJ/605/259
Title:
X-rays from HH 80/81 complex
Short Name:
J/ApJ/605/259
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report detections of X-rays from HH 80 and HH 81 with the ACIS instrument on the Chandra X-Ray Observatory. These are among the most luminous Herbig-Haro (HH) sources in the optical, and they are now the most luminous known in X-rays. These X-rays arise from the strong shocks that occur when the southern extension of this bipolar outflow slams into the ambient material. We imaged the central region of the bipolar flow revealing a complex of X-ray sources, including one near but not coincident with the putative power source in the radio and infrared.
25194. X-rays from large optical QSO sample
ID:
ivo://CDS.VizieR/J/ApJ/450/51
Title:
X-rays from large optical QSO sample
Short Name:
J/ApJ/450/51
Date:
21 Oct 2021
Publisher:
CDS
Description:
Of the more than 1000 QSOs in the Large Bright Quasar Survey (LBQS), we study the X-ray properties of 908 that were covered by the ROSAT All-Sky Survey (RASS). These data constitute among the largest, most homogeneous X-ray surveys of QSOs to date, and as such are well suited to the study of the multiwavelength properties of QSOs. Due to the ~600 s RASS exposure times, only 10% of the QSOs are detected in X-rays. However, by stacking X-ray counts, we obtain effectively much more sensitive observations for an average QSO in bins of redshift or luminosity, and for several classes of QSOs. We confirm a correlation of alpha_ox (slope of a hypothetical power law connecting 2500A and 2keV) with luminosity for the overall sample. For higher redshifts and optical luminosities, radio-loud QSOs appear to become progressively more luminous in X-rays than radio-quiet QSOs. The X-ray properties of a subsample of 36 broad absorption line QSOs suggest that they are strongly absorbed or underluminous in the X-rays, while a subsample of 22 Fe II-strong QSOs is anomalously X-ray bright.
25195. X-rays from the star-forming complex W40
ID:
ivo://CDS.VizieR/J/ApJ/725/2485
Title:
X-rays from the star-forming complex W40
Short Name:
J/ApJ/725/2485
Date:
21 Oct 2021
Publisher:
CDS
Description:
The young stellar cluster illuminating the W40 HII region, one of the nearest massive star-forming regions, has been observed with the ACIS detector on board the Chandra X-ray Observatory. Due to its high obscuration, this is a poorly studied stellar cluster with only a handful of bright stars visible in the optical band, including three OB stars identified as primary excitation sources. We detect 225 X-ray sources, of which 85% are confidently identified as young stellar members of the region. Two potential distances of the cluster, 260pc and 600pc, are used in the paper.
25196. X-rays in the Orion nebula cluster
ID:
ivo://CDS.VizieR/J/ApJ/584/911
Title:
X-rays in the Orion nebula cluster
Short Name:
J/ApJ/584/911
Date:
21 Oct 2021
Publisher:
CDS
Description:
A recent observation of the Orion Nebula Cluster with the ACIS instrument on board the Chandra X-Ray Observatory detected 1075 sources, 525 of which are pre-main-sequence (PMS) stars with measured bulk properties such as bolometric luminosities, masses, ages, and disk indicators. Nearly half of these stars have photometrically measured rotational periods. This provides a uniquely large and well-defined sample to study the dependence of magnetic activity on bulk properties for stars descending the Hayashi tracks.
25197. X-rays obs. in 8 young open star clusters
ID:
ivo://CDS.VizieR/J/other/JApA/34.393
Title:
X-rays obs. in 8 young open star clusters
Short Name:
J/other/JApA/34.
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a detailed investigation of X-ray source contents of eight young open clusters with ages between 4 to 46Myr using archival X-ray data from XMM-Newton. The probable cluster memberships of the X-ray sources have been established on the basis of multi-wavelength archival data, and samples of 152 pre-main sequence (PMS) low mass (<2M_{sun}_), 36 intermediate mass (2-10M_{sun}_) and 16 massive (>10M_{sun}_) stars have been generated. X-ray spectral analyses of high mass stars reveal the presence of high temperature plasma with temperature <2keV, and mean L_X_/L_bol_ of 10^-6.9^. In the case of PMS low mass stars, the plasma temperatures have been found to be in the range of 0.2keV to 3keV with a median value of ~1.3keV, with no significant difference in plasma temperatures during their evolution from 4 to 46Myr. The X-ray luminosity distributions of the PMS low mass stars have been found to be similar in the young star clusters under study. This may suggest a nearly uniform X-ray activity in the PMS low mass stars of ages ~4--14Myr. These observed values of L_X)/L_bol_ are found to have a mean value of 10^-3.6^+/-0.4, which is below the X-ray saturation level. The L_X_/L_bol_ values for the PMS low mass stars are well correlated with their bolometric luminosities, that implies its dependence on the internal structure of the low mass stars. The difference between the X-ray luminosity distributions of the intermediate mass stars and the PMS low mass stars has not been found to be statistically significant. Their L_X_/L_bol_ values, however have been found to be significantly different from each other with a confidence level greater than 99.999% and the strength of X-ray activity in the intermediate mass stars is found to be lower compared to the low mass stars. However, the possibility of X-ray emission from the intermediate mass stars due to a low mass star in close proximity of the intermediate mass star can not be ruled out.
25198. X-Ray source properties for NGC 2207/IC 2163
ID:
ivo://CDS.VizieR/J/ApJ/797/91
Title:
X-Ray source properties for NGC 2207/IC 2163
Short Name:
J/ApJ/797/91
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a comprehensive study of the total X-ray emission from the colliding galaxy pair NGC 2207/IC 2163, based on Chandra, Spitzer, and GALEX data. We detect 28 ultraluminous X-ray sources (ULXs), 7 of which were not detected previously because of X-ray variability. Twelve sources show significant long-term variability, with no correlated spectral changes. Seven sources are transient candidates. One ULX coincides with an extremely blue star cluster (B-V=-0.7). We confirm that the global relation between the number and luminosity of ULXs and the integrated star-formation rate (SFR) of the host galaxy also holds on local scales. We investigate the effects of dust extinction and age on the X-ray binary (XRB) population on subgalactic scales. The distributions of N_X_ and L_X_ are peaked at L_IR_/L_NUV_~1, which may be associated with an age of ~10 Myr for the underlying stellar population. We find that approximately one-third of the XRBs are located in close proximity to young star complexes. The luminosity function of the XRBs is consistent with that typical for high-mass XRBs and appears unaffected by variability. We disentangle and compare the X-ray diffuse spectrum with that of the bright XRBs. The hot interstellar medium dominates the diffuse X-ray emission at E<~1 keV and has a temperature kT=0.28_-0.04_^+0.05^ keV and intrinsic 0.5-2 keV luminosity of 7.9x10^40^ erg/s, a factor of ~2.3 higher than the average thermal luminosity produced per unit SFR in local star-forming galaxies. The total X-ray output of NGC 2207/IC 2163 is 1.5x10^41^ erg/s, and the corresponding total integrated SFR is 23.7 M_{sun}_/yr.
25199. X-ray sources around G12.82-0.02
ID:
ivo://CDS.VizieR/J/ApJ/665/1297
Title:
X-ray sources around G12.82-0.02
Short Name:
J/ApJ/665/1297
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a Chandra X-ray observation of G12.82-0.02, a shell-like radio supernova remnant coincident with the TeV gamma-ray source HESS J1813-178. We resolve the X-ray emission from the colocated Advanced Satellite for Cosmology and Astrophysics (ASCA) source into a point source surrounded by structured diffuse emission that fills the interior of the radio shell. The morphology of the diffuse emission strongly resembles that of a pulsar wind nebula.
25200. X-ray sources close to 3C 295 galaxy cluster
ID:
ivo://CDS.VizieR/J/A+A/484/303
Title:
X-ray sources close to 3C 295 galaxy cluster
Short Name:
J/A+A/484/303
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a detailed analysis of the overdensity of X-ray sources close to the 3C 295 galaxy cluster (z=0.46) to assess whether it is associated with a filament of the large-scale structure of the Universe. We obtained optical spectra of the optical counterparts of eleven sources associated with the filament, finding that one is at z=0.474. This is a type 1 AGN at 1.5' from the cluster center. We found three more sources with a redshift in the range 0.37/0.53. We extracted the stacked X-ray spectrum of 47 X-ray sources belonging to the putative filament.

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