- 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.
Number of results to display per page
Search Results
- 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.
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/895/71
- Title:
- 8um Cores in NGC 891, NGC 3628 and IC 5052
- Short Name:
- J/ApJ/895/71
- Date:
- 11 Mar 2022
- Publisher:
- CDS
- Description:
- To study the vertical distribution of the earliest stages of star formation in galaxies, three edge-on spirals, NGC891, NGC3628, and IC5052, observed by the Spitzer Space Telescope InfraRed Array Camera (IRAC) were examined for compact 8{mu}m cores using an unsharp mask technique; 173, 267, and 60 cores were distinguished, respectively. Color-color distributions suggest a mixture of polycyclic aromatic hydrocarbons and highly extincted photospheric emission from young stars. The average V-band extinction is ~20mag, equally divided between foreground and core. IRAC magnitudes for the clumps are converted to stellar masses assuming an age of 1Myr, which is about equal to the ratio of the total core mass to the star formation rate in each galaxy. The extinction and stellar mass suggest an intrinsic core radius of ~18pc for 5% star formation efficiency. The half-thickness of the disk of 8{mu}m cores is 105pc for NGC891 and 74pc for IC5052, varying with radius by a factor of ~2. For NGC3628, which is interacting, the half-thickness is 438pc, but even with this interaction, the 8{mu}m disk is remarkably flat, suggesting vertical stability. Small-scale structures like shingles or spirals are seen in the core positions. Very few of the 8{mu}m cores have optical counterparts.
- ID:
- ivo://CDS.VizieR/J/ApJS/245/14
- Title:
- 8um cores in the spiral arms of nearby galaxies
- Short Name:
- J/ApJS/245/14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spitzer Space Telescope observations of 15 spiral galaxies show numerous dense cores at 8{mu}m that are revealed primarily in unsharp mask images. The cores are generally invisible in optical bands because of extinction, and they are also indistinct at 8{mu}m alone because of contamination by more widespread diffuse emission. Several hundred core positions, magnitudes, and colors from the four InfraRed Array Camera bands are measured and tabulated for each galaxy. The larger galaxies, which tend to have longer and more regular spiral arms, often have their infrared cores aligned along these arms, with additional cores in spiral arm spurs. Galaxies without regular spirals have their cores in more irregular spiral-like filaments, with typically only one or two cores per filament. Nearly every elongated emission feature has 8{mu}m cores strung out along its length. The occurrence of dense cores in long and thin filaments is reminiscent of filamentary star formation in the solar neighborhood, although on a scale 100 times larger in galaxies. The cores most likely form by gravitational instabilities and cloud agglomeration in the filaments. The simultaneous occurrence of several cores with regular spacings in some spiral arms suggests that in these cases, all of the cores formed at about the same time and the corresponding filaments are young. Total star formation rates for the galaxies correlate with the total embedded stellar masses in the cores with an average ratio corresponding to a possible age between 0.2 and 2Myr. This suggests that the identified cores are the earliest phase for most star formation.
- ID:
- ivo://CDS.VizieR/J/ApJ/836/34
- Title:
- 24um excesses in clusters & membership of NGC2244
- Short Name:
- J/ApJ/836/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We characterize the first 40 Myr of evolution of circumstellar disks through a unified study of the infrared properties of members of young clusters and associations with ages from 2Myr up to ~40Myr: NGC1333, NGC1960, NGC2232, NGC2244, NGC2362, NGC2547, IC348, IC2395, IC4665, ChamaeleonI, OrionOB1a and OB1b, Taurus, the {beta} Pictoris Moving Group, {rho} Ophiuchi, and the associations of Argus, Carina, Columba, Scorpius-Centaurus, and Tucana-Horologium. Our work features: (1) a filtering technique to flag noisy backgrounds; (2) a method based on the probability distribution of deflections, P(D), to obtain statistically valid photometry for faint sources; and (3) use of the evolutionary trend of transitional disks to constrain the overall behavior of bright disks. We find that the fraction of disks three or more times brighter than the stellar photospheres at 24{mu}m decays relatively slowly initially and then much more rapidly by ~10Myr. However, there is a continuing component until ~35Myr, probably due primarily to massive clouds of debris generated in giant impacts during the oligarchic/chaotic growth phases of terrestrial planets. If the contribution from primordial disks is excluded, the evolution of the incidence of these oligarchic/chaotic debris disks can be described empirically by a log-normal function with the peak at 12-20Myr, including ~13% of the original population, and with a post-peak mean duration of 10-20Myr.
14850. 24um fluxes of GOODS-S AGN
- ID:
- ivo://CDS.VizieR/J/MNRAS/446/3199
- Title:
- 24um fluxes of GOODS-S AGN
- Short Name:
- J/MNRAS/446/3199
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of galaxies showing mid-infrared variability in data taken in the deepest Spitzer/MIPS 24{mu}m surveys in the Great Observatory Origins Deep Survey South field. We divide the data set in epochs and subepochs to study the long-term (months-years) and the short-term (days) variability. We use a {chi}^2^-statistics method to select active galactic nucleus (AGN) candidates with a probability <=1% that the observed variability is due to statistical errors alone. We find 39 (1.7% of the parent sample) sources that show long-term variability and 55 (2.2% of the parent sample) showing short-term variability. That is, 0.03sources/arcmin^2^ for both, long-term and short-term variable sources. After removing the expected number of false positives inherent to the method, the estimated percentages are 1.0 and 1.4% of the parent sample for the long term and short term, respectively. We compare our candidates with AGN selected in the X-ray and radio bands, and AGN candidates selected by their IR emission. Approximately, 50% of the MIPS (Multiband Imaging Photometer for Spitzer) 24{mu}m variable sources would be identified as AGN with these other methods. Therefore, MIPS 24{mu}m variability is a new method to identify AGN candidates, possibly dust obscured and low-luminosity AGN, that might be missed by other methods. However, the contribution of the MIPS 24{mu}m variable identified AGN to the general AGN population is small (<=13%) in GOODS-South.
