- ID:
- ivo://CDS.VizieR/J/MNRAS/459/140
- Title:
- M81, LMC and 3C 273/Coma 17-60keV obs.
- Short Name:
- J/MNRAS/459/140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a deep survey of three extragalactic fields, M81 (exposure of 9.7Ms), Large Magellanic Cloud (6.8 Ms) and 3C 273/Coma (9.3Ms), in the hard X-ray (17-60keV) energy band with the IBIS telescope onboard the INTEGRAL observatory, based on 12 years of observations (2003-2015). The combined survey reaches a 4{sigma} peak sensitivity of 0.18mCrab (2.6x10^-12^erg/s/cm^2^) and sensitivity better than 0.25 and 0.87mCrab over 10 per cent and 90 per cent of its full area of 4900 deg^2^, respectively. We have detected in total 147 sources at S/N>4{sigma}, including 37 sources observed in hard X-rays for the first time. The survey is dominated by extragalactic sources, mostly active galactic nuclei (AGN). The sample of identified sources contains 98 AGN (including 64 Seyfert galaxies, seven low-ionization nuclear emission-line region galaxies, three X-ray bright optically normal galaxies, 16 blazars and eight AGN of unclear optical class), two galaxy clusters (Coma and Abell 3266), 17 objects located in the Large and Small Magellanic Clouds (13 high- and two low-mass X-ray binaries and two X-ray pulsars), three Galactic cataclysmic variables, one ultraluminous X-ray source (M82 X-1) and one blended source (SWIFT J1105.7+5854). The nature of 25 sources remains unknown, so that the survey's identification is currently complete at 83 per cent. We have constructed AGN number-flux relations (log N-log S) and calculated AGN number densities in the local Universe for the entire survey and for each of the three extragalactic fields.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/601/735
- Title:
- M51 luminous X-ray sources
- Short Name:
- J/ApJ/601/735
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of two Chandra observations (separated by 1yr) of the population of X-ray sources in the spiral galaxy M51 (NGC 5194 and NGC 5195). One hundred and thirteen X-ray sources have been detected in an 8.4'x8.4'(20.4x20.4kpc) region, and 84 and 12 of them project within the disks of NGC 5194 and NGC 5195, respectively. Nine and 28 sources have luminosities exceeding 1x10^39^erg/s (ultraluminous X-ray sources or ULXs) and 1x10^38^erg/s in the 0.5-8keV band, respectively, assuming that they are associated with M51. The number of ULXs is much higher than found in most normal spiral and elliptical galaxies. Most of the X-ray sources and all seven of the ULXs in NGC 5194 are located in, or close to, a spiral arm, suggesting a connection with recent star formation.
- ID:
- ivo://CDS.VizieR/J/A+A/426/119
- Title:
- 1.2mm mapping of RCW 106 Giant Molecular Cloud
- Short Name:
- J/A+A/426/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have mapped the dust continuum emission from the molecular cloud covering a region of 28pcx94pc associated with the well-known H II region RCW 106 at 1.2mm using SIMBA on SEST. The observations, having an HPBW of 24" (0.4pc), reveal 95 clumps, of which about 50% have MSX associations and only 20% have IRAS associations. Owing to their higher sensitivity to colder dust and higher angular resolution the present observations identify new emission features and also show that most of the IRAS sources in this region consist of multiple dust emission peaks. The detected millimeter sources (MMS) include on one end the exotic MMS5 (associated with IRAS 16183-4958, one of the brightest infrared sources in our Galaxy) and the bright (and presumably cold) source MMS54, with no IRAS or MSX associations on the other end. Around 10% of the sources are associated with signposts of high mass star formation activity.
- ID:
- ivo://CDS.VizieR/J/ApJ/855/140
- Title:
- MMT spectra of SNRs and SNR candidates in M33
- Short Name:
- J/ApJ/855/140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To date, over 220 emission nebulae in M33 have been identified as supernova remnants (SNRs) or SNR candidates, principally through [SII]:H{alpha} line ratios that are elevated compared to those in HII regions. In many cases, the determination of a high [SII]:H{alpha} line ratio was made using narrow-band interference filter images and has not been confirmed spectroscopically. Here, we present MMT 6.5m optical spectra that we use to measure [SII]:H{alpha} and other line ratios in an attempt to determine the nature of these suggested candidates. Of the 197 objects in our sample, 120 have no previously published spectroscopic observations. We confirm that the majority of candidate SNRs have emission line ratios characteristic of SNRs. While no candidates show Doppler-broadened lines expected from young, ejecta-dominated SNRs (>~1000km/s), a substantial number do exhibit lines that are broader than HII regions. We argue that the majority of the objects with high [SII]:H{alpha} line ratios (>0.4) are indeed SNRs, but the distinction between HII regions and SNRs becomes less obvious at low surface brightness, and additional criteria, such as X-ray detection, are needed. We discuss the properties of the sample as a whole and compare it with similar samples in other nearby galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/819/46
- Title:
- Models of thermonuclear X-ray bursters
- Short Name:
- J/ApJ/819/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the KEPLER 1D hydrodynamics code (Woosley et al. 2004ApJS..151...75W), 464 models of thermonuclear X-ray bursters were performed across a range of accretion rates and compositions. We present the library of simulated burst profiles from this sample, and examine variations in the simulated light curve for different model conditions. We find that the recurrence time varies as a power law against accretion rate, and measure its slope while mixed H/He burning is occurring for a range of metallicities, finding the power law gradient to vary from {eta}=1.1 to 1.24. We identify the accretion rates at which mixed H/He burning stops and a transition occurs to different burning regimes. We explore how varying the accretion rate and metallicity affects burst morphology in both the rise and tail.
- ID:
- ivo://CDS.VizieR/J/A+A/562/A2
- Title:
- 100-month Swift catalogue of SFXTs
- Short Name:
- J/A+A/562/A2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Supergiant Fast X-ray Transients (SFXTs) are High Mass X-ray Binaries (HMXBs) that are defined by their hard X-ray flaring behaviour. During such flares they reach peak luminosities of 10^36^-10^37^erg/s for a few hours (in the hard X-ray): much shorter timescales than those characterizing Be/X-ray binaries. We investigate the characteristics of bright flares (detections in excess of 5{sigma}) for a sample of SFXTs and their relation to the orbital phase. We have retrieved all Swift/BAT Transient Monitor light curves, and collected all detections in excess of 5{sigma} from both daily- and orbital-averaged light curves in the time range 2005 February 12 to 2013 May 31 (MJD 53413-56443). We also considered all on-board detections as recorded in the same time span and selected those within 4 arcmin of each source in our sample and in excess of 5{sigma}. We present a catalogue of over a thousand BAT flares from 11 SFXTs, down to 15-150keV fluxes of ~6x10^-10^erg/cm^2^/s (daily timescale) and ~1.5x10^-9^erg/cm^2^/s (orbital timescale, averaging ~800s) and spanning 100 months. The great majority of these flares are unpublished. This population is characterized by short (a few hundred seconds) and relatively bright (in excess of 100mCrab, 15-50keV) events. In the hard X-ray, these flares last in general much less than a day. Clustering of hard X-ray flares can be used to indirectly measure the length of an outburst, even when the low-level emission is not detected. We construct the distributions of flares, of their significance (in terms of sigma) and their flux as a function of orbital phase, to infer the properties of these binary systems. In particular, we observe a trend of clustering of flares at some phases as P_orb increases, as consistent with a progression from tight, circular or mildly eccentric orbits at short periods, to wider and more eccentric orbits at longer orbital periods. Finally, we estimate the expected number of flares for a given source for our limiting flux and provide the recipe for calculating them for the limiting flux of future hard X-ray observatories.
- ID:
- ivo://CDS.VizieR/J/AJ/140/533
- Title:
- Morphologies of selected AGN
- Short Name:
- J/AJ/140/533
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the optical morphologies of candidate active galaxies identified at radio, X-ray, and mid-infrared wavelengths. We use the Advanced Camera for Surveys General Catalog (ACS-GC) to identify 372, 1360, and 1238 active galactic nucleus (AGN) host galaxies from Very Large Array, XMM-Newton, and Spitzer Space Telescope observations of the COSMOS field, respectively. We investigate both quantitative (GALFIT) and qualitative (visual) morphologies of these AGN host galaxies, split by brightness in their selection band.
- ID:
- ivo://CDS.VizieR/J/A+A/655/A93
- Title:
- Mrk 501 long-term multi-band photometry
- Short Name:
- J/A+A/655/A93
- Date:
- 14 Mar 2022 07:47:04
- Publisher:
- CDS
- Description:
- Radio-to-TeV observations of the bright nearby (z=0.034) blazar Markarian 501 (Mrk 501), performed from December 2012 to April 2018, are used to study the emission mechanisms in its relativistic jet. We examined the multi-wavelength variability and the correlations of the light curves obtained by eight different instruments, including the First G-APD Cherenkov Telescope (FACT), observing Mrk 501 in very high-energy (VHE) gamma-rays at TeV energies. We identified individual TeV and X-ray flares and found a sub-day lag between variability in these two bands. The source was found to be variable on different timescales. Simultaneous TeV and X-ray variations with almost zero lag are consistent with synchrotron self-Compton (SSC) emission, where TeV photons are produced through inverse Compton scattering. The characteristic time interval of 5-25 days between TeV flares is consistent with them being driven by Lense-Thirring precession.
- ID:
- ivo://CDS.VizieR/J/A+A/655/A89
- Title:
- Mrk421 multi-instrument observations in 2017
- Short Name:
- J/A+A/655/A89
- Date:
- 21 Mar 2022 08:46:33
- Publisher:
- CDS
- Description:
- We present a detailed characterisation and theoretical interpretation of the broadband emission of the paradigmatic TeV blazar Mrk 421, with a special focus on the multi-band flux correlations. The dataset has been collected through an extensive multi-wavelength campaign organised between 2016 December and 2017 June. The instruments involved are MAGIC, FACT, Fermi-LAT, Swift, GASP-WEBT, OVRO, Medicina, and Metsahovi. Additionally, four deep exposures (several hours long) with simultaneous MAGIC and NuSTAR observations allowed a precise measurement of the falling segments of the two spectral components. The very-high-energy (VHE; E>100GeV) gamma rays and X-rays are positively correlated at zero time lag, but the strength and characteristics of the correlation change substantially across the various energy bands probed. The VHE versus X-ray fluxes follow different patterns, partly due to substantial changes in the Compton dominance for a few days without a simultaneous increase in the X-ray flux (i.e. orphan gamma-ray activity). Studying the broadband spectral energy distribution (SED) during the days including NuSTAR observations, we show that these changes can be explained within a one-zone leptonic model with a blob that increases its size over time. The peak frequency of the synchrotron bump varies by two orders of magnitude throughout the campaign. Our multi-band correlation study also hints at an anti-correlation between UV-optical and X-ray at a significance higher than 3{sigma}. A VHE flare observed on MJD~57788 (2017 February 4) shows gamma-ray variability on multi-hour timescales, with a factor ten increase in the TeV flux but only a moderate increase in the keV flux. The related broadband SED is better described by a two-zone leptonic scenario rather than by a one-zone scenario. We find that the flare can be produced by the appearance of a compact second blob populated by high energetic electrons spanning a narrow range of Lorentz factors, from {gamma}'_min_=2x10^4^ to {gamma}'_max_=6x10^5^.
- ID:
- ivo://CDS.VizieR/J/ApJ/758/129
- Title:
- 4Ms Chandra Deep Field South 6-8keV galaxies
- Short Name:
- J/ApJ/758/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the 4Ms Chandra Deep Field-South (CDF-S) survey, we have identified a sample of 6845 X-ray-undetected galaxies that dominates the unresolved {approx}20%-25% of the 6-8keV cosmic X-ray background (XRB). This sample was constructed by applying mass and color cuts to sources from a parent catalog based on GOODS-South Hubble Space Telescope z-band imaging of the central 6' radius area of the 4Ms CDF-S. The stacked 6-8keV detection is significant at the 3.9{sigma} level, but the stacked emission was not detected in the 4-6keV band, which indicates the existence of an underlying population of highly obscured active galactic nuclei (AGNs). Further examinations of these 6845 galaxies indicate that the galaxies on the top of the blue cloud and with redshifts of 1<~z<~3, magnitudes of 25<~z_850_<~28, and stellar masses of 2x10^8^<~M_{sstarf}_/M_{sun}_<~2x10^9^ make the majority contributions to the unresolved 6-8keV XRB. Such a population is seemingly surprising given that the majority of the X-ray-detected AGNs reside in massive (>~10^10^M_{sun}_) galaxies. We discuss constraints upon this underlying AGN population, supporting evidence for relatively low mass galaxies hosting highly obscured AGNs, and prospects for further boosting the stacked signal.