- ID:
- ivo://CDS.VizieR/J/ApJ/892/102
- Title:
- XMM X-ray data of Planck ESZ galaxy clusters
- Short Name:
- J/ApJ/892/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the scaling relations derived by fitting the X-ray parameters determined from analyzing the XMM-Newton observations of 120 galaxy clusters in the Planck Early Sunyaev-Zel'dovich (SZ) sample spanning the redshift range of 0.059<z<0.546. We find that the slopes of all the investigated scaling relations significantly deviate from the self-similar predictions, if self-similar redshift evolution is assumed. When the redshift evolution is left free to vary, the derived slopes are more in agreement with the self-similar predictions. Relaxed clusters have on average ~30% higher X-ray luminosity than disturbed clusters at a given mass, a difference that, depending on the relative fraction of relaxed and disturbed clusters in the samples (e.g., SZ vs. X-ray selected), has a strong impact on the normalization obtained in different studies. Using the core-excised cluster luminosities reduces the scatter and brings into better agreement the L-M_tot_ and L-T relations determined for different samples. M_tot_-T, M_tot_-YX, and M_tot_-M_gas_ relations show little dependence on the dynamical state of the clusters, but the normalizations of these relations may depend on the mass range investigated. Although most of the clusters investigated in this work reside at relatively low redshift, the fits prefer values of {gamma}, the parameter accounting for the redshift evolution, different from the self-similar predictions. This suggests an evolution (<2{sigma} level, with the exception of the M_tot_-T relation) of the scaling relations. For the first time, we find significant evolution (>3{sigma}) of the M_tot_-T relation, pointing to an increase of the kinetic-to-thermal energy ratio with redshift. This is consistent with a scenario in which higher-redshift clusters are on average more disturbed than their lower-redshift counterparts.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/419/47
- Title:
- XMM X-ray fluxes in Coma cluster
- Short Name:
- J/A+A/419/47
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The XMM-Newton survey of the Coma cluster of galaxies covers an area of 1.86 square degrees with a mosaic of 16 pointings and has a total useful integration time of 400ks. Detected X-ray sources with extent less than 10" were correlated with catalogued galaxies in the Coma cluster region. The redshift information, which is abundant in this region of the sky, allowed us to separate cluster members from background and foreground galaxies. For the background sources, we recover a typical logN-logS in the flux range 10^-15^-10^-13^erg/s/cm^2^ in the 0.5-2.0keV band.
- ID:
- ivo://CDS.VizieR/J/A+A/550/A18
- Title:
- XMM X-ray sources in Fornax dwarf galaxy
- Short Name:
- J/A+A/550/A18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of a deep archive XMM-Newton observation of the Fornax spheroidal galaxy that we analyzed with the aim of fully characterizing the X-ray source population (in most of the cases likely to be background active galactic nuclei) detected towards the target. A cross correlation with the available databases allowed us to find a source that may be associated with a variable star belonging to the galaxy. We also searched for X-ray sources in the vicinity of the Fornax globular clusters GC 3 and GC 4 and found two sources probably associated with the respective clusters. The deep X-ray observation was also suitable for the search of the intermediate-mass black hole (of mass~=10^4^M_{sun}_) expected to be hosted in the center of the galaxy. In the case of Fornax, this search is extremely difficult since the galaxy centroid of gravity is poorly constrained because of the large asymmetry observed in the optical surface brightness. Since we cannot firmly establish the existence of an X-ray counterpart of the putative black hole, we put constraints only on the accretion parameters. In particular, we found that the corresponding upper limit on the accretion efficiency, with respect to the Eddington luminosity, is as low as a few 10^-5^.
- ID:
- ivo://CDS.VizieR/J/A+A/639/A5
- Title:
- X-ray absorption in INTEGRAL AGN
- Short Name:
- J/A+A/639/A5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work the INTEGRAL hard X-ray selected sample of AGN has been used to investigate the possible contribution of absorbing material distributed within the host galaxies to the total amount of NH measured in the X-ray band. We collected all the available axial ratio measurements of the galaxies hosting our AGN together with their morphological information and find that also for our hard X-ray selected sample a deficit of edge-on galaxies hosting type 1 AGN is present. We estimate that in our hard X-ray selected sample there is a deficit of 24% (+/-5%) of type 1 AGN. Possible bias in redshift has been excluded, as we found the same effect in a well determined range of z where the number and the distributions of the two classes are statistically the same. Our findings clearly indicate that material located in the host galaxy on scales of hundreds of parsecs and not aligned with the putative absorbing torus of the AGN can contribute to the total amount of column density. This galactic absorber can be large enough to hide the broad line region of some type 1 AGN causing their classification as type 2 objects and giving rise to the deficiency of type 1 in edge-on galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/648/A121
- Title:
- X-ray activity and accretion in the ONC
- Short Name:
- J/A+A/648/A121
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Recent works highlight the importance of stellar X-rays on the evolution of the circumstellar disks of young stellar objects, especially for disk photoevaporation. A signature of this process may be seen in the so far tentatively observed dependence of stellar accretion rates on X-ray luminosities. According to models of X-ray driven photoevaporation, stars with higher X-ray luminosities should show lower accretion rates, on average, in a sample with similar masses and ages. To this aim, we have analyzed X-ray properties of young stars in the Orion Nebula Cluster determined with Chandra during the COUP observation as well as accretion data obtained from the photometric catalog of the HST Treasury Program. With these data, we have performed a statistical analysis of the relation between X-ray activity and accretion rates using partial linear regression analysis. The initial anticorrelation found with a sample of 332 young stars is considerably weaker compared to previous studies. However, excluding flaring activity or limiting the X-ray luminosity to the soft band (0.5-2.0keV) leads to a stronger anticorrelation, which is statistically more significant. Furthermore, we have found a weak positive correlation between the higher component of the plasma temperature gained in the X-ray spectral fitting and the accretion rates, indicating that the hardness of the X-ray spectra may influence the accretion process. There is evidence for a weak anticorrelation, as predicted by theoretical models, suggesting that X-ray photoevaporation modulates the accretion rate through the inner disk at late stages of disk evolution, leading to a phase of photoevaporation-starved accretion.
- ID:
- ivo://CDS.VizieR/J/other/RAA/19.98
- Title:
- X-ray activity from different types of stars
- Short Name:
- J/other/RAA/19.9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- X-ray emission is an important indicator of stellar activity. In this paper, we study stellar X-ray activity using the XMM-Newton and LAMOST data for different types of stars. We provide a sample including 1259 X-ray-emitting stars, of which 1090 have accurate stellar parameter estimations. Our sample size is much larger than those used in previous works. We find a bimodal distribution of the X-ray to optical flux ratio (log(fX/fV)) for G and K stars. We interpret that this bimodality is due to two subpopulations with different coronal heating rates. Furthermore, using the full widths at half maxima calculated from H{alpha} and H{beta} lines, we show that these stars in the inactive peaks have smaller rotational velocities. This is consistent with the magnetic dynamo theory that presumes stars with low rotational velocities have low levels of stellar activity. We also examine the correlation between log(fX/fV) and luminosity of the excess emission in the H{alpha} line, and find a tight relation between the coronal and chromospheric activity indicators.
- ID:
- ivo://CDS.VizieR/J/MNRAS/422/2024
- Title:
- X-ray-age relation and exoplanet evaporation
- Short Name:
- J/MNRAS/422/2024
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the relationship between coronal X-ray emission and stellar age for late-type stars, and the variation of this relationship with spectral type. We select 717 stars from 13 open clusters and find that the ratio of X-ray to bolometric luminosity during the saturated phase of coronal emission decreases from 10^-3.1^ for late K-dwarfs to 10^-4.3^ for early F-type stars (across the range 0.29<(B-V)_0_<1.41). Our determined saturation timescales vary between 10^7.6^ and 10^8.3^ years, though with no clear trend across the whole FGK range. We apply our X-ray emission - age relations to the investigation of the evaporation history of 121 known transiting exoplanets using a simple energy -limited model of evaporation and taking into consideration Roche lobe effects and different heating/evaporation efficiencies. We confirm that a linear cut-off of the planet distribution in the M^2^/R^3^ versus a^-2^ plane is an expected result of population modification by evaporation and that the known transiting exoplanets display such a cut-off. We find that for an evaporation efficiency of 25 percent we expect around 1 in 5 of the known transiting exoplanets to have lost >10 percent of their mass since formation. In addition we provide estimates of the minimum formation mass for which a planet could be expected to survive for 4Gyrs for a range of stellar and planetary parameters. We emphasise the importance of the earliest periods of a planet's life for its evaporation history with 75 percent expect to occur within the first Gyr. This raises the possibility of using evaporation histories to distinguish different migration mechanisms. For planets with spin-orbit angles available from measurements of the Rossiter-McLaughlin effect no difference is found between the distributions of planets with misaligned orbits and those with aligned orbits. This suggests that dynamical effects accounting for misalignment occur early in the life of a planetary system, although additional data is required to test this.
- ID:
- ivo://CDS.VizieR/J/AJ/126/2209
- Title:
- X-ray AGN from RASS and SDSS
- Short Name:
- J/AJ/126/2209
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the initial results of a new program aimed to ultimately yield ~10^4^ fully characterized X-ray source identifications - a sample about an order of magnitude larger than earlier efforts. The technique is detailed and employs X-ray data from the ROSAT All-Sky Survey (RASS, Cat. <IX/10>, <IX/29>) and optical imaging and spectroscopic follow-up from the Sloan Digital Sky Survey (SDSS, <J/AJ/123/567>); these two surveys prove to be serendipitously very well matched in sensitivity. As part of the SDSS software pipelines, optical objects in the SDSS photometric catalogs are automatically positionally cross-correlated with RASS X-ray sources. Then priorities for follow-on SDSS optical spectra of candidate counterparts are automatically assigned using an algorithm based on the known ratios of fX/fopt for various classes of X-ray emitters at typical RASS fluxes of 10^-13^ergs/cm^2^/s. SDSS photometric parameters for optical morphology, magnitude, and colors, plus FIRST radio information, serve as proxies for object class.
- 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/ApJ/743/166
- Title:
- X-ray and infra-red study of RCW 38
- Short Name:
- J/ApJ/743/166
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the structure of the high-mass star-forming region RCW 38 and the spatial distribution of its young stellar population. Spitzer Infrared Array Camera (IRAC) photometry (3-8um) is combined with Two Micron All Sky Survey near-IR data to identify young stellar objects (YSOs) by IR-excess emission from their circumstellar material. Chandra X-ray data are used to identify class III pre-main-sequence stars lacking circumstellar material. We identify 624 YSOs: 23 class 0/I and 90 flat spectrum protostars, 437 class II stars, and 74 class III stars. We also identify 29 (27 new) O star candidates over the IRAC field. Seventy-two stars exhibit IR-variability, including 7 class 0/I and 12 flat spectrum YSOs. A further 177 tentative candidates are identified by their location in the IRAC [3.6] versus [3.6]-[5.8] color-magnitude diagram. We find strong evidence of subclustering in the region.
