- ID:
- ivo://CDS.VizieR/J/A+A/637/A12
- Title:
- Northern disk of M31 XMM-Newton images
- Short Name:
- J/A+A/637/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use new deep XMM-Newton observations of the northern disk of M31 to trace the hot interstellar medium (ISM) in unprecedented detail and to characterise the physical properties of the X-ray emitting plasmas. We used all XMM-Newton data up to and including our new observations to produce the most detailed image yet of the hot ISM plasma in a grand design spiral galaxy such as our own. We compared the X-ray morphology to multi-wavelength studies in the literature to set it in the context of the multi-phase ISM. We performed spectral analyses on the extended emission using our new observations as they offer sufficient depth and count statistics to constrain the plasma properties. Data from the Panchromatic Hubble Andromeda Treasury were used to estimate the energy injected by massive stars and their supernovae. We compared these results to the hot gas properties. The brightest emission regions were found to be correlated with populations of massive stars, notably in the 10kpc star-forming ring. The plasma temperatures in the ring regions are ~0.2keV up to ~0.6keV. We suggest this emission is hot ISM heated in massive stellar clusters and superbubbles. We derived X-ray luminosities, densities, and pressures for the gas in each region. We also found large extended emission filling low density gaps in the dust morphology of the northern disk, notably between the 5kpc and 10kpc star-forming rings. We propose that the hot gas was heated and expelled into the gaps by the populations of massive stars in the rings. It is clear that the massive stellar populations are responsible for heating the ISM to X-ray emitting temperatures, filling their surroundings, and possibly driving the hot gas into the low density regions. Overall, the morphology and spectra of the hot gas in the northern disk of M 31 is similar to other galaxy disks.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/137/2981
- Title:
- Northern Optical Cluster Survey. III.
- Short Name:
- J/AJ/137/2981
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the complete galaxy cluster catalog from the Northern Sky Optical Cluster Survey, a new, objectively defined catalog of candidate galaxy clusters at z<~0.25 drawn from the Digitized Second Palomar Observatory Sky Survey (DPOSS). The data presented here cover the Southern Galactic Cap, as well as the less well-calibrated regions of the Northern Galactic Cap. In addition, due to improvements in our cluster finder and measurement methods, we provide an updated catalog for the well-calibrated Northern Galactic Cap region previously published in Paper II (Cat. J/AJ/125/2064). The complete survey covers 11411deg^2^, with over 15000 candidate clusters.
- ID:
- ivo://CDS.VizieR/J/MNRAS/457/110
- Title:
- Northern XMM-XXL field AGN catalog
- Short Name:
- J/MNRAS/457/110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents a survey of X-ray-selected active galactic nuclei (AGNs) with optical spectroscopic follow-up in a ~18deg^2^ area of the equatorial XMM-XXL north field. A sample of 8445 point-like X-ray sources detected by XMM-Newton above a limiting flux of F_0.5-10keV_>10^-15^erg/cm2/s was matched to optical (Sloan Digital Sky Survey, SDSS) and infrared (IR; WISE) counterparts. We followed up 3042 sources brighter than r=22.5mag with the SDSS Baryon Oscillation Spectroscopic Survey (BOSS) spectrograph. The spectra yielded a reliable redshift measurement for 2578 AGNs in the redshift range z=0.02-5.0, with 0.5-2keV luminosities ranging from 10^39^-10^46^erg/s. This is currently the largest published spectroscopic sample of X-ray-selected AGNs in a contiguous area. The BOSS spectra of AGN candidates show a distribution of optical line widths which is clearly bimodal, allowing an efficient separation between broad- and narrow-emission line AGNs. The former dominate our sample (70 per cent) due to the relatively bright X-ray flux limit and the optical BOSS magnitude limit. We classify the narrow-emission line objects (22 per cent of the full sample) using standard optical emission line diagnostics: the majority have line ratios indicating the dominant source of ionization is the AGN. A small number (8 per cent of the full sample) exhibit the typical narrow line ratios of star-forming galaxies, or only have absorption lines in their spectra. We term the latter two classes 'elusive' AGN, which would not be easy to identify correctly without their X-ray emission. We also compare X-ray (XMM-Newton), optical colour (SDSS) and and IR (WISE) AGN selections in this field. X-ray observations reveal, by far, the largest number of AGN. The overlap between the selections, which is a strong function of the imaging depth in a given band, is also remarkably small. We show using spectral stacking that a large fraction of the X-ray AGNs would not be selectable via optical or IR colours due to host galaxy contamination. A substantial fraction of AGN may therefore be missed by these longer wavelength selection methods.
- ID:
- ivo://CDS.VizieR/J/MNRAS/508/5176
- Title:
- NuSTAR Extragalactic Surveys, NEP Field
- Short Name:
- J/MNRAS/508/5176
- Date:
- 03 Dec 2021 13:27:09
- Publisher:
- CDS
- Description:
- We present the NuSTAR extragalactic survey of the James Webb Space Telescope (JWST) North Ecliptic Pole (NEP) Time-Domain Field. The survey covers a ~0.16deg^2^ area with a total exposure of 681ks acquired in a total of nine observations from three epochs. The survey sensitivities at 20% of the area are 2.39, 1.14, 2.76, 1.52, and 5.20x10^-14^erg/cm^2^/s in the 3-24, 3-8, 8-24, 8-16, and 16-24keV bands, respectively. The NEP survey is one of the most sensitive extragalactic surveys with NuSTAR so far. A total of 33 sources were detected above 95% reliability in at least one of the five bands. We present the number counts, logN-logS, measured in the hard X-ray 8-24 and 8-16keV bands, uniquely accessible by NuSTAR down to such faint fluxes. We performed source detection on the XMM-Newton and Chandra observations of the same field to search for soft X-ray counterparts of each NuSTAR detection. The soft band positions were used to identify optical and infrared associations. We present the X-ray properties (hardness ratio and luminosity) and optical-to-X-ray properties of the detected sources. The measured fraction of candidate Compton-thick (NH>=10^24^cm^-2^) active galactic nuclei, derived from the hardness ratio, is between 3% to 27%. As this survey was designed to have variability as its primary focus, we present preliminary results on multi-epoch flux variability in the 3-24keV band.
- ID:
- ivo://CDS.VizieR/J/ApJS/235/17
- Title:
- NuSTAR Extragalactic Surveys: UDS field
- Short Name:
- J/ApJS/235/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results and the source catalog of the NuSTAR survey in the UKIDSS Ultra Deep Survey (UDS) field, bridging the gap in depth and area between NuSTAR's ECDFS and COSMOS surveys. The survey covers a ~0.6deg^2^ area of the field for a total observing time of ~1.75Ms, to a half-area depth of ~155ks corrected for vignetting at 3-24keV, and reaching sensitivity limits at half-area in the full (3-24keV), soft (3-8keV), and hard (8-24keV) bands of 2.2x10^-14^erg/cm^2^/s, 1.0x10^-14^erg/cm^2^/s, and 2.7x10^-14^erg/cm^2^/s, respectively. A total of 67 sources are detected in at least one of the three bands, 56 of which have a robust optical redshift with a median of <z>~1.1. Through a broadband (0.5-24keV) spectral analysis of the whole sample combined with the NuSTAR hardness ratios, we compute the observed Compton-thick (CT; N_H_>10^24^cm^-2^) fraction. Taking into account the uncertainties on each NH measurement, the final number of CT sources is 6.8+/-1.2. This corresponds to an observed CT fraction of 11.5%+/-2.0%, providing a robust lower limit to the intrinsic fraction of CT active galactic nuclei and placing constraints on cosmic X-ray background synthesis models.
- ID:
- ivo://CDS.VizieR/J/ApJ/825/132
- Title:
- NuSTAR hard X-ray survey of the Galactic Center. II.
- Short Name:
- J/ApJ/825/132
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first survey results of hard X-ray point sources in the Galactic Center (GC) region by NuSTAR. We have discovered 70 hard (3-79 keV) X-ray point sources in a 0.6 deg^2^ region around Sgr A* with a total exposure of 1.7 Ms, and 7 sources in the Sgr B2 field with 300 ks. We identify clear Chandra counterparts for 58 NuSTAR sources and assign candidate counterparts for the remaining 19. The NuSTAR survey reaches X-ray luminosities of ~4x and ~8x10^32^ erg/s at the GC (8 kpc) in the 3-10 and 10-40 keV bands, respectively. The source list includes three persistent luminous X-ray binaries (XBs) and the likely run-away pulsar called the Cannonball. New source-detection significance maps reveal a cluster of hard (>10 keV) X-ray sources near the Sgr A diffuse complex with no clear soft X-ray counterparts. The severe extinction observed in the Chandra spectra indicates that all the NuSTAR sources are in the central bulge or are of extragalactic origin. Spectral analysis of relatively bright NuSTAR sources suggests that magnetic cataclysmic variables constitute a large fraction (>40%-60%). Both spectral analysis and logN-logS distributions of the NuSTAR sources indicate that the X-ray spectra of the NuSTAR sources should have kT>20 keV on average for a single temperature thermal plasma model or an average photon index of {Gamma}=1.5-2 for a power-law model. These findings suggest that the GC X-ray source population may contain a larger fraction of XBs with high plasma temperatures than the field population.
- ID:
- ivo://CDS.VizieR/J/ApJ/836/99
- Title:
- NuSTAR serendipitous survey: the 40-month catalog
- Short Name:
- J/ApJ/836/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first full catalog and science results for the Nuclear Spectroscopic Telescope Array (NuSTAR) serendipitous survey. The catalog incorporates data taken during the first 40 months of NuSTAR operation, which provide ~20Ms of effective exposure time over 331 fields, with an areal coverage of 13deg^2^, and 497 sources detected in total over the 3-24keV energy range. There are 276 sources with spectroscopic redshifts and classifications, largely resulting from our extensive campaign of ground-based spectroscopic follow-up. We characterize the overall sample in terms of the X-ray, optical, and infrared source properties. The sample is primarily composed of active galactic nuclei (AGNs), detected over a large range in redshift from z=0.002 to 3.4 (median of <z>=0.56), but also includes 16 spectroscopically confirmed Galactic sources. There is a large range in X-ray flux, from log(f_3-24keV_/erg/s/cm^2^)~-14 to -11, and in rest-frame 10-40keV luminosity, from log(L_10-40keV_/erg/s)~39 to 46, with a median of 44.1. Approximately 79% of the NuSTAR sources have lower-energy (<10keV) X-ray counterparts from XMM-Newton, Chandra, and Swift XRT. The mid-infrared (MIR) analysis, using WISE all-sky survey data, shows that MIR AGN color selections miss a large fraction of the NuSTAR-selected AGN population, from ~15% at the highest luminosities (L_X_>10^44^erg/s) to ~80% at the lowest luminosities (L_X_<10^43^erg/s). Our optical spectroscopic analysis finds that the observed fraction of optically obscured AGNs (i.e., the type 2 fraction) is F_Type2_=53_-15_^+14^% , for a well-defined subset of the 8-24keV selected sample. This is higher, albeit at a low significance level, than the type 2 fraction measured for redshift- and luminosity-matched AGNs selected by <10keV X-ray missions.
- ID:
- ivo://CDS.VizieR/J/ApJ/808/185
- Title:
- NuSTAR surveys: COSMOS catalog
- Short Name:
- J/ApJ/808/185
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To provide the census of the sources contributing to the X-ray background peak above 10keV, Nuclear Spectroscopic Telescope Array (NuSTAR) is performing extragalactic surveys using a three-tier "wedding cake" approach. We present the NuSTAR survey of the COSMOS field, the medium sensitivity, and medium area tier, covering 1.7deg^2^ and overlapping with both Chandra and XMM-Newton data. This survey consists of 121 observations for a total exposure of ~3Ms. To fully exploit these data, we developed a new detection strategy, carefully tested through extensive simulations. The survey sensitivity at 20% completeness is 5.9, 2.9, and 6.4x10^-14^erg/cm^2^/s in the 3-24, 3-8, and 8-24keV bands, respectively. By combining detections in 3 bands, we have a sample of 91 NuSTAR sources with 10^42^-10^45.5^erg/cm^2^/s luminosities and redshift z=0.04-2.5. Thirty-two sources are detected in the 8-24keV band with fluxes ~100 times fainter than sources detected by Swift-BAT. Of the 91 detections, all but 4 are associated with a Chandra and/or XMM-Newton point-like counterpart. One source is associated with an extended lower energy X-ray source. We present the X-ray (hardness ratio and luminosity) and optical-to-X-ray properties. The observed fraction of candidate Compton-thick active galactic nuclei measured from the hardness ratio is between 13%-20%. We discuss the spectral properties of NuSTAR J100259+0220.6 (ID 330) at z=0.044, with the highest hardness ratio in the entire sample. The measured column density exceeds 10^24^/cm2, implying the source is Compton-thick. This source was not previously recognized as such without the >10keV data.
- ID:
- ivo://CDS.VizieR/J/ApJ/808/184
- Title:
- NuSTAR surveys: ECDF-S catalog
- Short Name:
- J/ApJ/808/184
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the initial results and the source catalog from the Nuclear Spectroscopic Telescope Array (NuSTAR) survey of the Extended Chandra Deep Field South (hereafter, ECDFS) --currently the deepest contiguous component of the NuSTAR extragalactic survey program. The survey covers the full ~30'x30' area of this field to a maximum depth of ~360ks (~220ks when corrected for vignetting at 3-24keV), reaching sensitivity limits of ~1.3x10^-14^erg/s/cm^2^ (3-8keV), ~3.4x10^-14^erg/s/cm^2^ (8-24keV), and ~3.0x10^-14^erg/s/cm^2^ (3-24keV). A total of 54 sources are detected over the full field, although five of these are found to lie below our significance threshold once contaminating flux from neighboring (i.e., blended) sources is taken into account. Of the remaining 49 that are significant, 19 are detected in the 8-24keV band. The 8-24 to 3-8keV band ratios of the 12 sources that are detected in both bands span the range 0.39-1.7, corresponding to a photon index range of {Gamma}~0.5-2.3, with a median photon index of {Gamma}{bar}=1.70+/-0.52. The redshifts of the 49 sources in our main sample span the range z=0.21-2.7, and their rest-frame 10-40keV luminosities (derived from the observed 8-24keV fluxes) span the range L_10-40keV_~(0.7-300)x10^43^erg/s, sampling below the "knee" of the X-ray luminosity function out to z~0.8-1. Finally, we identify one NuSTAR source that has neither a Chandra nor an XMM-Newton counterpart, but that shows evidence of nuclear activity at infrared wavelengths and thus may represent a genuine, new X-ray source detected by NuSTAR in the ECDFS.
- ID:
- ivo://CDS.VizieR/J/A+A/638/A45
- Title:
- Obscuration properties of red AGNs in XXL-N
- Short Name:
- J/A+A/638/A45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The combination of optical and mid-infrared (MIR) photometry has been extensively used to select red active galactic nuclei (AGNs). Our aim is to explore the obscuration properties of these red AGNs with both X-ray spectroscopy and spectral energy distributions (SEDs). In this study, we re-visit the relation between optical/MIR extinction and X-ray absorption. We use IR selection criteria, specifically the W1 and W2 WISE bands, to identify 4798 AGNs in the XMM-XXL area (~25deg^2^). Application of optical/MIR colours (r-W2>6) reveals 561 red AGNs (14%). Of these, 47 have available X-ray spectra with at least 50 net (background-subtracted) counts per detector. For these sources, we construct SEDs from the optical to the MIR using the CIGALE code. The SED fitting shows that 44 of these latter 47 sources present clear signs of obscuration based on the AGN emission and the estimated inclination angle. Fitting the SED also reveals ten systems (~20%) which are dominated by the galaxy. In these cases, the red colours are attributed to the host galaxy rather than AGN absorption. Excluding these ten systems from our sample and applying X-ray spectral fitting analysis shows that up to 76% (28/37) of the IR red AGNs present signs of X-ray absorption. Thus, there are nine sources (~20% of the sample) that although optically red, are not substantially X-ray absorbed. Approximately 50% of these sources present broad emission lines in their optical spectra. We suggest that the reason for this apparent discrepancy is that the r-W2 criterion is sensitive to smaller amounts of obscuration relative to the X-ray spectroscopy. In conclusion, it appears that the majority of red AGNs present considerable obscuration levels as shown by their SEDs. Their X-ray absorption is moderate with a mean of N_H_~10^22^cm^-2^.