- ID:
- ivo://CDS.VizieR/J/MNRAS/362/1065
- Title:
- XMM/Chandra study of IC 10
- Short Name:
- J/MNRAS/362/1065
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an X-ray study of our nearest starburst galaxy IC 10, based on XMM-Newton and Chandra observations. A list of 73 XMM-Newton and 28 Chandra detections of point-like X-ray sources in the field is provided; a substantial fraction of them are likely stellar objects in the Milky Way due to the low Galactic latitude location of IC 10.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/815/129
- Title:
- X-ray AGNs with Subaru/FMOS NIR observations
- Short Name:
- J/ApJ/815/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the Eddington ratio distribution of X-ray-selected broad-line active galactic nuclei (AGNs) in the redshift range 1.0<z<2.2, where the number density of AGNs peaks. Combining the optical and Subaru/Fiber Multi Object Spectrograph near-infrared spectroscopy, we estimate black hole masses for broad-line AGNs in the Chandra Deep Field South (CDF-S), Extended Chandra Deep Field South (E-CDF-S), and the XMM-Newton Lockman Hole (XMM-LH) surveys. AGNs with similar black hole masses show a broad range of AGN bolometric luminosities, which are calculated from X-ray luminosities, indicating that the accretion rate of black holes is widely distributed. We find a substantial fraction of massive black holes accreting significantly below the Eddington limit at z<~2, in contrast to what is generally found for luminous AGNs at high redshift. Our analysis of observational selection biases indicates that the "AGN cosmic downsizing" phenomenon can be simply explained by the strong evolution of the comoving number density at the bright end of the AGN luminosity function, together with the corresponding selection effects. However, one might need to consider a correlation between the AGN luminosity and the accretion rate of black holes, in which luminous AGNs have higher Eddington ratios than low-luminosity AGNs, in order to understand the relatively small fraction of low-luminosity AGNs with high accretion rates in this epoch. Therefore, the observed downsizing trend could be interpreted as massive black holes with low accretion rates, which are relatively fainter than less-massive black holes with efficient accretion.
- ID:
- ivo://CDS.VizieR/J/AJ/132/1100
- Title:
- X-ray and IR sources in RCW 38
- Short Name:
- J/AJ/132/1100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on results of a 96.7ks Chandra observation of one of the youngest, most embedded, and most massive young stellar clusters studied in X-rays: RCW 38. We detect 460 sources in the field, of which 360 are confirmed to be associated with the RCW 38 cluster. The cluster members range in luminosity from 10^30^ to 10^33.5^ergs/s. Over 10% of the cluster members with over 100 counts exhibit flares, while about 15% of the cluster members with over 30 counts are variable. Of the sources identified as cluster members, 160 have near-infrared (NIR) counterparts either in the Two Micron All Sky Survey database or detected via Very Large Telescope observations. Of these, about 20% appear to have optically thick disks. An additional 353 members are identified through NIR observations, of which at least 50% possess optically thick disks. We fit over 100 X-ray sources as absorbed Raymond-Smith-type plasmas and find that the column to the cluster members varies from 10^21.5^ to 10^23^cm^-2^. We compare the gas to dust absorption signatures in these stars and find NH=A_V_(2x10^21^)cm^-2^. We find that the cluster contains 31 candidate OB stars and is centered about 10" (0.1pc) west of the primary source of the ionization, the O5 star IRS 2. The cluster has a peak central density of about 400 X-ray sources/pc^2^. We estimate that the total cluster membership exceeds 2000 stars.
- ID:
- ivo://CDS.VizieR/J/A+A/359/113
- Title:
- X-ray and IR study of Rho Oph dark cloud
- Short Name:
- J/A+A/359/113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained two deep exposures of the {rho} Oph cloud core region with the ROSAT High Resolution Imager. The improved position accuracy (1"-6") with respect to previous recent X-ray observations (ROSAT PSPC, and ASCA) allows us to remove positional ambiguities for the detected sources. We also cross-correlate the X-ray positions with IR sources found in the ISOCAM survey of the same region at 6.7 and 14.3{mu}m, in addition to sources (optical and IR) known from ground-based observations, which are young stars (T Tauri stars, with and without circumstellar disks, and protostars). We thus obtain the best-studied sample of X-ray emitting stars in a star-forming region (63 X-ray sources detected, and 55 identified).
- ID:
- ivo://CDS.VizieR/J/AJ/130/2212
- Title:
- X-ray and NIR studies of L1448
- Short Name:
- J/AJ/130/2212
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of X-ray and near-infrared (NIR) observations of L1448, a star-forming region in the Perseus cloud complex using the Chandra X-Ray Observatory and the 4m telescope at the Kitt Peak National Observatory. We detect 72 X-ray sources in a ~17'x17' region with a 68 ks ACIS exposure down to the X-ray flux limit of ~10^-15^ergs/s/cm2 (0.5-8keV), for which we conduct follow-up NIR imaging observations in a concentric ~11'x11' region with FLAMINGOS down to mi_Ks_~17mag. Twelve X-ray sources have NIR or optical counterparts.
- ID:
- ivo://CDS.VizieR/J/ApJ/613/393
- Title:
- X-ray and radio sources in {rho} Oph Core A
- Short Name:
- J/ApJ/613/393
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A 96ks Chandra X-ray observation of {rho} Ophiuchus cloud core A detected 87 sources, of which 60 were identified with counterparts at other wavelengths. Simultaneous multifrequency Very Large Array (VLA) observations detected 31 radio sources at 6cm, of which 10 were also detected by Chandra. We report new radio detections of the optically invisible IR source WLY 2-11 and the faint H{alpha} emission line star Elias 24 (class II).
- ID:
- ivo://CDS.VizieR/J/ApJ/892/18
- Title:
- X-ray & MIR luminosities of the GBT galaxies
- Short Name:
- J/ApJ/892/18
- Date:
- 19 Jan 2022 08:55:44
- Publisher:
- CDS
- Description:
- We present an investigation of the dependence of H_2_O maser detection rates and properties on the mid-IR active galactic nucleus (AGN) luminosity, L_AGN_, and the obscuring column density, N_H_, based on mid-IR and hard X-ray photometry. Based on spectral energy distribution fitting that allows for decomposition of the black hole accretion and star formation components in the mid-infrared, we show that the megamaser (disk maser) detection rate increases sharply for galaxies with 12{mu}m AGN luminosity L_12um_^AGN^ greater than 10^42^erg/s, from <~3% (<~2%) to ~12% (~5%). By using the ratio of the observed X-ray to mid-IR AGN luminosity as an indicator of N_H_, we also find that megamaser (disk maser) detection rates are boosted to 15% (7%) and 20% (9%) for galaxies with N_H_>=10^23^/cm^2^ and N_H_>=10^24^cm^-2^, respectively. Combining these column density cuts with a constraint for high L_12um_^AGN^ (>=10^42^erg/s) predicts further increases in the megamaser (disk maser) detection rates to 19% (8%) and 27% (14%), revealing unprecedented potential increases of the megamaser and disk maser detection rates by a factor of 7-15 relative to the current rates, depending on the chosen sample selection criteria. A noteworthy aspect of these new predictions is that the completeness rates are only compromised mildly, with the rates remaining at the level of ~95% (~50%) for sources with N_H_>=10^23^/cm^2^ (N_H_>=10^24^/cm^2^). Applying these selection methods to current X-ray AGN surveys predicts the detection of >~15 new megamaser disks.
- ID:
- ivo://CDS.VizieR/J/MNRAS/367/627
- Title:
- X-ray/NIR correlation for early-type galaxies
- Short Name:
- J/MNRAS/367/627
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The relation between X-ray luminosity and near-infrared (NIR) luminosity for early-type galaxies has been examined. NIR luminosities should provide a superior measure of stellar mass compared to optical luminosities used in previous studies, especially if there is significant star formation or dust present in the galaxies. However, we show that the X-ray-NIR relations are remarkably consistent with the X-ray-optical relations. This indicates that the large scatter of the relations is dominated by scatter in the X-ray properties of early-type galaxies, and is consistent with early-types consisting of old, quiescent stellar populations. We have investigated scatter in terms of environment, surface brightness profile, Mg2, H{beta}, H{gamma} line strength indices, spectroscopic age and nuclear H{alpha} emission.
- ID:
- ivo://CDS.VizieR/J/A+A/501/485
- Title:
- X-ray properties of Chandra red galaxies
- Short Name:
- J/A+A/501/485
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the X-ray properties of the extremely red objects (ERO) population observed by Chandra with three partially overlapping pointings (up to ~90ks) over an area of ~500arcmin^2^, down to a 0.5-8keV flux limit of ~10-15erg/cm^2^/s. We selected EROs using a multi-band photometric catalog down to a Ks-band magnitude of ~19.3 (Vega system); 14 EROs were detected in X-rays, corresponding to ~9% of the overall X-ray source population (149 X-ray sources) and to ~5% of the ERO population (288). The X-ray emission of all X-ray detected EROs is consistent with that of an active galactic nucleus (AGN) (>~3.5x10^42^erg/s at photometric redshifts z>1), in agreement with previous X-ray observations, with an indication of increasing absorption between the three X-ray brightest EROs and the 11 X-ray faintest EROs.
- 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.
