- ID:
- ivo://CDS.VizieR/J/MNRAS/446/470
- Title:
- ULX candidates in luminous infrared galaxies
- Short Name:
- J/MNRAS/446/470
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a Chandra study of ultraluminous X-ray sources (ULXs) in a sample of 17 nearby (D_L_<60Mpc) luminous infrared galaxies (LIRGs), selected to have star formation rates (SFRs) in excess of 7M_{sun}_/yr and low foreground Galactic column densities (N_H_<~5x10^20^cm^-2^). A total of 53 ULXs were detected and we confirm that this is a complete catalogue of ULXs for the LIRG sample. We examine the evolution of ULX spectra with luminosity in these galaxies by stacking the spectra of individual objects in three luminosity bins, finding a distinct change in spectral index at luminosity ~2x10^39^erg/s. This may be a change in spectrum as 10M_{sun}_ black holes transit from an ~ Eddington to a super-Eddington accretion regime, and is supported by a plausible detection of partially ionized absorption imprinted on the spectrum of the luminous ULX (L_X_~5x10^39^erg/s) CXOU J024238.9-000055 in NGC 1068, consistent with the highly ionized massive wind that we would expect to see driven by a super-Eddington accretion flow. This sample shows a large deficit in the number of ULXs detected per unit SFR (0.2 versus 2 ULXs, per M_{sun}_/yr) compared to the detection rate in nearby (D_L_<14.5Mpc) normal star-forming galaxies. This deficit also manifests itself as a lower differential X-ray luminosity function normalization for the LIRG sample than for samples of other star-forming galaxies. We show that it is unlikely that this deficit is a purely observational effect. Part of this deficit might be attributable to the high metallicity of the LIRGs impeding the production efficiency of ULXs and/or a lag between the star formation starting and the production of ULXs; however, we argue that the evidence - including very low N_ULX_/L_FIR_, and an even lower ULX incidence in the central regions of the LIRGs - shows that the main culprit for this deficit is likely to be the high column of gas and dust in these galaxies, that fuels the high SFR but also acts to obscure many ULXs from our view.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/143/144
- Title:
- ULX candidates in nearby Arp galaxies
- Short Name:
- J/AJ/143/144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a statistical analysis of the ultra-luminous X-ray point sources (ULXs; L_X_>=10^39^erg/s) in a sample of galaxies selected from the Arp Atlas of Peculiar Galaxies (1996, Cat. VII/192; Webb, 1996, Cat. VII/192). We find a possible enhancement of a factor of ~2-4 in the number of ULXs per blue luminosity for the strongly interacting subset. Such an enhancement would be expected if ULX production is related to star formation, as interacting galaxies tend to have enhanced star formation rates on average. For most of the Arp galaxies in our sample, the total number of ULXs compared to the far-infrared luminosity is consistent with values found earlier for spiral galaxies. This suggests that for these galaxies, ULXs trace recent star formation. However, for the most infrared-luminous galaxies, we find a deficiency of ULXs compared to the infrared luminosity. For these very infrared-luminous galaxies, active galactic nuclei may contribute to powering the far-infrared; alternatively, ULXs may be highly obscured in the X-ray in these galaxies and therefore not detected by these Chandra observations. We determined local UV/optical colors within the galaxies in the vicinity of the candidate ULXs using Galaxy Evolution Explorer UV and Sloan Digitized Sky Survey optical images. In most cases, the distributions of colors are similar to the global colors of interacting galaxies. However, the u-g and r-i colors at the ULX locations tend to be bluer on average than these global colors, suggesting that ULXs are preferentially found in regions with young stellar populations. In the Arp sample there is a possible enhancement of a factor of ~2-5 in the fraction of galactic nuclei that are X-ray-bright compared to more normal spirals.
- ID:
- ivo://CDS.VizieR/J/ApJ/741/49
- Title:
- ULX candidates in nearby galaxies
- Short Name:
- J/ApJ/741/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- One hundred seven ultraluminous X-ray sources (ULXs) with 0.3-10.0keV luminosities in excess of 10^39^erg/s are identified in a complete sample of 127 nearby galaxies. The sample includes all galaxies within 14.5Mpc above the completeness limits of both the Uppsala Galaxy Catalogue (Cat. VII/26) and the Infrared Astronomical Satellite survey (Cat. II/125). The galaxy sample spans all Hubble types, a four-decade range in mass, 7.5<log(M/M_{sun}_)<11.4, and in star formation rate, 0.0002<SFR(M_{sun}_/yr)<=3.6. ULXs are detected in this sample at rates of one per 3.2x10^10^M_{sun}_, one per ~0.5M_{sun}_/yr star formation rate, and one per 57Mpc^3^ corresponding to a luminosity density of ~2x10^37^erg/s/Mpc^3^. At these rates we estimate as many as 19 additional ULXs remain undetected in fainter dwarf galaxies within the survey volume. An estimated 14 objects, or 13%, of the 107 ULX candidates are expected to be background sources. The differential ULX luminosity function shows a power-law slope {alpha}~-0.8 to -2.0 with an exponential cutoff at ~20x10^39^erg/s with precise values depending on the model and on whether the ULX luminosities are estimated from their observed numbers of counts or, for a subset of candidates, from their spectral shapes. Extrapolating the observed luminosity function predicts at most one very luminous ULX, L_X_~10^41^erg/s, within a distance as small as 100Mpc. The luminosity distribution of ULXs within the local universe cannot account for the recent claims of luminosities in excess of 2x10^41^erg/s, requiring a new population class to explain these extreme objects.
- ID:
- ivo://CDS.VizieR/J/ApJ/649/730
- Title:
- ULX population in nearby galaxies from XMM
- Short Name:
- J/ApJ/649/730
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an archival XMM-Newton study of the bright X-ray point sources (LX>10^38^ergs/s) in 32 nearby galaxies. From our list of approximately 100 point sources, we attempt to determine if there is a low-state counterpart to the ultraluminous X-ray (ULX) population, searching for a soft-hard state dichotomy similar to that known for Galactic X-ray binaries and testing the specific predictions of the intermediate-mass black hole (IMBH) hypothesis. To this end, we searched for low-state objects, which we defined as objects within our sample that had a spectrum well fitted by a simple absorbed power law, and high-state objects, which we defined as objects better fitted by a combined blackbody and a power law.
- ID:
- ivo://CDS.VizieR/J/A+A/452/739
- Title:
- ULX sources and FIRST radio sources
- Short Name:
- J/A+A/452/739
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We search for ultra luminous X-ray source (ULXs) radio counterparts located in nearby galaxies in order to constrain their physical nature. Our work is based on a systematic cross-identification of the most recent and extensive available ULX catalogues and archival radio data. A catalogue of 70 positional coincidences is reported. Most of them are located within the galaxy nucleus. Among them, we find 11 new cases of non-nuclear ULX sources with possibly associated radio emission.
- ID:
- ivo://CDS.VizieR/J/ApJ/878/71
- Title:
- ULXs with multiepoch Spitzer/IRAC obs.
- Short Name:
- J/ApJ/878/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a mid-infrared (IR) sample study of nearby ultraluminous X-ray sources (ULXs) using multiepoch observations with the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. Spitzer/IRAC observations taken after 2014 were obtained as part of the Spitzer Infrared Intensive Transients Survey. Our sample includes 96 ULXs located within 10 Mpc. Of the 96 ULXs, 12 have candidate counterparts consistent with absolute mid-IR magnitudes of supergiants, and 16 counterparts exceeded the mid-IR brightness of single supergiants and are thus more consistent with star clusters or non-ULX background active galactic nuclei. The supergiant candidate counterparts exhibit a bimodal color distribution in a Spitzer/IRAC color-magnitude diagram, where "red" and "'blue" ULXs fall in IRAC colors [3.6]-[4.5]~0.7 and [3.6]-[4.5]~0.0, respectively. The mid-IR colors and absolute magnitudes of four "red" and five "blue" ULXs are consistent with those of supergiant B[e] (sgB[e]) and red supergiant (RSG) stars, respectively. Although "blue," RSG-like mid-IR ULX counterparts likely host RSG mass donors; we propose that "red" counterparts are ULXs exhibiting the "B[e] phenomenon" rather than hosts of sgB[e] mass donors. We show that the mid-IR excess from the "red" ULXs is likely due to thermal emission from circumstellar or circumbinary dust. Using dust as a probe for total mass, we estimate mass-loss rates of dM/dt~1x10^-4^M_{sun}_/yr in dust-forming outflows of red ULXs. Based on the transient mid-IR behavior and its relatively flat spectral index, {alpha}=-0.19+/-0.1, we suggest that the mid-IR emission from Holmberg IX X-1 originates from a variable jet.
- ID:
- ivo://CDS.VizieR/J/ApJS/120/399
- Title:
- ULYSSES supplement to GRB 3B catalog
- Short Name:
- J/ApJS/120/399
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present interplanetary network localization information for 218 gamma-ray bursts in the third BATSE catalog obtained by analyzing the arrival times of these bursts with the Ulysses and Compton Gamma Ray Observatory spacecraft. For any given burst observed by these two spacecraft, arrival time analysis (or "triangulation") results in an annulus of possible arrival directions whose half-width varies between 7'' and 32', depending on the intensity and time history of the burst and the distance of the Ulysses spacecraft from Earth. This annulus generally intersects the BATSE error circle, which results in an average reduction of a factor of 30 of the error box area.
20068. UMa Group
- ID:
- ivo://CDS.VizieR/J/AJ/105/226
- Title:
- UMa Group
- Short Name:
- J/AJ/105/226
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Ursa Major Group (UMaG) is studied as a test case for the authenticity of Stellar Kinematic Groups, using Coravel radial velocities, recent compilations of astrometric data and new spectroscopic observations. Spectroscopic age indicators, particularly indices of the strength of chromospheric emission, are applied to solar-type candidate members of UMaG, and it is shown that stars that meet the spectroscopic criteria also have kinematics that agree better with the space motions of the nucleus of UMaG than does the starting sample as a whole. The primary limitation on the precision of kinematics is now parallaxes instead of radial velocities. These more restrictive kinematic criteria are then applied to other UMaG candidates and a list summarizing membership is presented. UMaG is also examined as a cluster, confirming its traditional age of 0.3 Gyr and a mean [Fe/H] of -0.08 +/- 0.09 for those stars most likely to be bona fide members.
- ID:
- ivo://CDS.VizieR/J/PASJ/61/177
- Title:
- 15um AKARI observations in CDFS field
- Short Name:
- J/PASJ/61/177
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Deep observations of the Chandra Deep Field South have been secured at 15um with AKARI/IRC infrared space telescope. From these observations, we define a sample of mid infrared-selected galaxies at 15um and we also obtain 15um flux densities for a sample of Lyman Break Galaxies at z~1 already observed at 24um with Spitzer/MIPS.
20070. 55 UMa spectroscopic orbit
- ID:
- ivo://CDS.VizieR/J/A+A/309/521
- Title:
- 55 UMa spectroscopic orbit
- Short Name:
- J/A+A/309/521
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The first investigation of the known triple system 55 UMa (2.55d binary in a ~1870-d orbit with the third star) based on electronic spectra led to several new findings about the system: (1) Discovery of spectral lines of the tertiary and an unambiguous detection of the lines of the secondary. Spectra of both primary and tertiary are of the same strength and correspond to spectral class A0V. The secondary spectrum is about twice fainter in the visual region and belongs probably also to spectral class A. (2) First self-consistent orbital solution describing close and wide orbit and the detection of apsidal motion for the close pair. The orbital period of the close pair was improved to (2.5538380+/-0.0000046d) and basic physical elements for all three stars and the system were estimated. The orbital solution also gives the period of apsidal motion of the close pair of (450+/-60)yr and leads to a good agreement with the published speckle-interferometric orbit for the distant companion if the longitude of periastron passage is increased by 180deg.