A deep Chandra survey for faint X-ray sources in the Galactic globular cluster M30, and searches for optical and radio counterparts

2020 ◽  
Vol 499 (3) ◽  
pp. 3338-3355
Author(s):  
Yue Zhao ◽  
Craig O Heinke ◽  
Haldan N Cohn ◽  
Phyllis M Lugger ◽  
Sebastien Guillot ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Hubble Space Telescope ◽  
Cataclysmic Variables ◽  
Galactic Nuclei ◽  
Point Sources ◽  
Very Large Array ◽  
X Ray ◽  
Radial Profiles

ABSTRACT We present a deep (∼330 ks) Chandra survey of the Galactic globular cluster M30 (NGC 7099). Combining the new Cycle 18 with the previous Cycle 3 observations we report a total of 10 new X-ray point sources within the 1${_{.}^{\prime}}$03 half-light radius, compiling an extended X-ray catalogue of a total of 23 sources. We incorporate imaging observations by the Hubble Space Telescope and the Karl G. Jansky Very Large Array from the MAVERIC survey to search for optical and radio counterparts to the new and old sources. Two X-ray sources are found to have a radio counterpart, including the known millisecond pulsar PSR J2140−2310A, the radio position of which also matches a previously reported faint optical counterpart which is slightly redder than the main sequence. We found optical counterparts to 18 of the 23 X-ray sources, identifying two new cataclysmic variables (CVs), five new CV candidates, two new candidates of RS CVn type of active binary (AB), and two new candidates of BY Dra type of AB. The remaining unclassified X-ray sources are likely background active galactic nuclei (AGNs), as their number is consistent with the expected number of AGN at our X-ray sensitivity. Finally, our analysis of radial profiles of different source classes suggests that bright CVs are more centrally distributed than faint CVs in M30, consistent with other core-collapsed globular clusters.

Multiwavelength analysis of OH Megamaser galaxies: The case of IRAS11506-3851

2020 ◽  
Vol 15 (S359) ◽  
pp. 347-349
Author(s):  
Carpes P. Hekatelyne ◽  
Thaisa Storchi-Bergmann
Keyword(s):  
Active Galactic Nuclei ◽  
Hubble Space Telescope ◽  
Galactic Nuclei ◽  
Large Array ◽  
Very Large Array ◽  
Star Forming ◽  
Star Forming Regions ◽  
Field Unit ◽  
Mixed Transition ◽  
Integral Field

AbstractWe present Multi-Object Spectrograph (GMOS) Integral Field Unit (IFU), Hubble Space Telescope (HST) and Very Large Array (VLA) observations of the inner kpc of the OH Megamaser galaxy IRAS 11506-3851. In this work we discuss the kinematics and excitation of the gas as well as its radio emission. The HST images reveal an isolated spiral galaxy and the combination with the GMOS-IFU flux distributions allowed us to identify a partial ring of star-forming regions surrounding the nucleus with a radius of ≍500 pc. The emission-line ratios and excitation map reveal that the region inside the ring present mixed/transition excitation between those of Starbursts and Active Galactic Nuclei (AGN), while regions along the ring are excited by Starbursts. We suggest that we are probing a buried or fading AGN that could be both exciting the gas and originating an outflow.

Commission N°48: High Energy Astrophysics (Astrophysique Des Hautes Energies)

1988 ◽  
Vol 20 (1) ◽  
pp. 671-675
Author(s):  
C.J. Cesarsky ◽  
R.A. Sunyaev ◽  
G.W. Clark ◽  
R. Giacconi ◽  
Vin-Yue Qu ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Supernova Remnants ◽  
Cataclysmic Variables ◽  
Galactic Nuclei ◽  
High Energy ◽  
Clusters Of Galaxies ◽  
High Energy Astrophysics ◽  
X Ray ◽  
X Ray Binaries ◽  
Imaging Telescopes

The european X-ray observatory (EXOSAT), which was launched in 1983 and which finished operations in April 1986, has brought a rich harvest of results in the period 1984-1987, surveyed here. The EXOSAT payload consisted of three sets of instruments: two low energy imaging telescopes (LE:E<2 KeV), a medium-energy experiment (ME:E=l-50KeV) and a gas scintillation proportional counter (GSPC:E=2-20KeV). Over most of the energy range covered, EXOSAT was not more sensitive than its predecessor, the american EINSTEIN satellite. But the EINSTEIN satellite is far from having exhausted the treasures of the X-ray sky. And EXOSAT, thanks to its elliptical 90-hour orbit, had the extra advantage of being able to make long, continuous observations of interesting objects, lasting up to 72 hours. Thus, EXOSAT was very well suited for variability studies, and many of its most important findings are in this area. EXOSAT observations sample a vide range of astrophysical sources: X-ray binaries, cataclysmic variables and active stars; supernova remnants and the interstellar medium; active galactic nuclei, and clusters of galaxies. Among the highlights, let us mention:

scholarly journals Theory of Accretion Disk Coronae

1990 ◽  
Vol 115 ◽  
pp. 187-196
Author(s):  
T. R. Kallman
Keyword(s):  
Active Galactic Nuclei ◽  
Accretion Disk ◽  
Cataclysmic Variables ◽  
Galactic Nuclei ◽  
X Ray ◽  
Spectral Signatures ◽  
Low Mass ◽  
X Ray Absorption ◽  
X Ray Binaries ◽  
Theoretical Issues

AbstractAccretion disk coronae are likely to be the dominant site for X-ray absorption and reprocessed emission in low mass X-ray binaries, and may be present in other classes of compact X-ray sources such as active galactic nuclei and cataclysmic variables. In spite of this fact, and in spite of the observational evidence for their existence, there remain many uncertainties about the structure of accretion disk coronae. This paper will discuss the coronal structure and dynamics, their X-ray spectral signatures including coupling to the variability behavior of compact X-ray sources, and the major unsolved theoretical issues surrounding them.

scholarly journals X-Ray Binaries in Globular Clusters

1988 ◽  
Vol 126 ◽  
pp. 347-366
Author(s):  
Jonathan E. Grindlay
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Cataclysmic Variables ◽  
Line Emission ◽  
Brightness Distribution ◽  
Burst Source ◽  
X Ray ◽  
Compact Binaries ◽  
Central Surface ◽  
X Ray Binaries

X-ray binaries in globular clusters provide a powerful tool for the exploration of the evolution of compact binaries and their host globular clusters. Recent x-ray and optical studies of these systems have yielded long-sought binary periods and fundamental properties for two sources (in NGC 6624 and M 15). It appears that tidal capture formation of compact binaries in globular clusters can proceed by several different routes and lead to exotic systems such as the white dwarf-neutron star binary with an 11-minute period recently discovered in NGC 6624. Combined with previously reported long-term periods for several globular cluster (and field) x-ray sources, this suggests again that many of these systems may in fact be hierarchical triple systems. The prospects for forming these in the dense cores of clusters undergoing core collapse is discussed, and searches for color gradients in the cores of globular clusters showing cusps in their central surface brightness distribution are presented. A program to test for the high central density of binaries (and triples) expected in cusp clusters by searching for diffuse line emission from their constituent cataclysmic variables is briefly described. Finally, the case for globular cluster disruption and the formation of galactic x-ray burst source is reviewed in light of recent developments.

scholarly journals Composite Spectra of Some Active Galactic Nuclei

1989 ◽  
Vol 134 ◽  
pp. 189-190
Author(s):  
Sachiko Tsuruta
Keyword(s):  
Active Galactic Nuclei ◽  
Hubble Space Telescope ◽  
Galactic Nuclei ◽  
Space Missions ◽  
X Ray ◽  
Power House ◽  
Central Engine ◽  
Composite Spectra ◽  
Future Space ◽  
Composite Models

Recent years have seen some progress in the studies of the central engine of active galactic nuclei (AGN). On the observational side, past space missions such as HEAO-A, Einstein and EXOSAT have brought some considerable progress in the observations of X-ray spectra and time variabilities of AGN. More significant progress is expected in the immediate future due to the current and future space missions such as IUE, GINGA, the Hubble Space Telescope, ASTRO-D, ROSAT, and AXAF. Therefore, it would be important to continue parallel theoretical studies. In this report composite models are presented which naturally explain the observed continuum radiation from seyferts and radio-quiet quasars. Our aim is to explore the central engine of AGN. This class of AGN is selected because it is generally considered to give the most direct information on the central power-house.

scholarly journals High density of active galactic nuclei in the outskirts of distant galaxy clusters

2019 ◽  
Vol 623 ◽  
pp. L10 ◽  
Author(s):  
E. Koulouridis ◽  
I. Bartalucci
Keyword(s):  
Active Galactic Nuclei ◽  
Galaxy Clusters ◽  
Statistical Significance ◽  
Galactic Nuclei ◽  
Average Density ◽  
Point Sources ◽  
Source Surface ◽  
Essential Property ◽  
X Ray ◽  
Massive Clusters

We present a study of the distribution of X-ray detected active galactic nuclei (AGN) in the five most massive, M500SZ > 1014 M⊙, and distant, z ∼ 1, galaxy clusters in the Planck and South Pole Telescope (SPT) surveys. The spatial and thermodynamic individual properties of each cluster have been defined with unprecedented accuracy at this redshift using deep X-ray observations. This is an essential property of our sample in order to precisely determine the R500Yx radius of the clusters. For our purposes, we computed the X-ray point-like source surface density in 0.5 R500Yx wide annuli up to a clustercentric distance of 4 R500Yx, statistically subtracting the background and accounting for the respective average density of optical galaxies. We found a significant excess of X-ray point sources between 2 and 2.5 R500Yx at the 99.9% confidence level. The results clearly display for the first time strong observational evidence of AGN triggering in the outskirts of high-redshift massive clusters with such a high statistical significance. We argue that the particular conditions at this distance from the cluster centre increase the galaxy merging rate, which is probably the dominant mechanism of AGN triggering in the outskirts of massive clusters.

scholarly journals New hard X-ray sources discovered in the ongoing INTEGRAL Galactic plane survey after 14 yr of observations

2017 ◽  
Vol 470 (1) ◽  
pp. 512-516 ◽  
Author(s):  
Roman A. Krivonos ◽  
Sergey S. Tsygankov ◽  
Ilya A. Mereminskiy ◽  
Alexander A. Lutovinov ◽  
Sergey Yu. Sazonov ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Gamma Ray ◽  
Galactic Plane ◽  
Cataclysmic Variables ◽  
Galactic Nuclei ◽  
Pulsar Wind Nebulae ◽  
X Ray ◽  
Sky Survey ◽  
The Galaxy ◽  
Pulsar Wind

Abstract The International Gamma-Ray Astrophysics Laboratory (INTEGRAL) continues to successfully work in orbit after its launch in 2002. The mission provides the deepest ever survey of hard X-ray sources throughout the Galaxy at energies above 20 keV. We report on a catalogue of new hard X-ray source candidates based on the latest sky maps comprising 14 yr of data acquired with the IBIS telescope onboard INTEGRAL in the Galactic Plane (|b| &lt; 17.5°). The current catalogue includes in total 72 hard X-ray sources detected at S/N &gt; 4.7σ and not known to previous INTEGRAL surveys. Among them, 31 objects have also been detected in the on-going all-sky survey by the BAT telescope of the Swift observatory. For 26 sources on the list, we suggest possible identifications: 21 active galactic nuclei, two cataclysmic variables, two isolated pulsars or pulsar wind nebulae and one supernova remnant; 46 sources from the catalogue remain unclassified.

scholarly journals Probing ultra-diffuse galaxies out to the virial radius of the Coma cluster with XMM–Newton

2021 ◽  
Author(s):  
M S Mirakhor ◽  
S A Walker
Keyword(s):  
Globular Clusters ◽  
Galactic Nuclei ◽  
Current Data ◽  
Point Sources ◽  
Dark Matter Halo ◽  
Coma Cluster ◽  
X Ray ◽  
Hot Gas ◽  
Low Mass ◽  
X Ray Binaries

Abstract We probe the formation scenarios and the active galactic nuclei (AGN) occupation fraction of ultra-diffuse galaxies (UDGs) in the nearby Coma cluster by utilizing XMM−Newton observations of 779 out of 854 UDG candidates identified by Subaru survey. Their origin is probed by measuring the dark matter halo mass of the stacked sample of UDGs and the population of low-mass X-ray binaries residing in globular clusters. Our measurements suggest that the average UDG population does not have a substantial amount of hot gas or a large number of globular clusters. This supports the formation scenario, in which UDGs are puffed-up dwarf galaxies, agreeing with that obtained for 404 Coma cluster UDGs using Chandra. We also determine AGN occupation fraction of UDGs by cross-correlating the position of UDGs with the detected point sources in Coma. We detect three X-ray sources with detection significance σ ≥ 5 that could be off-centre AGN within 5 arcsec from the centre of the UDG 317, UDG 432, and UDG 535. We identify an optical counterpart for the X-ray source associated with the UDG 317, suggesting that this source is more likely an off-centre AGN. Based on the current data, however, we cannot conclusively constrain whether the detected AGN is residing in the Coma cluster or not.

scholarly journals The XXL Survey

2018 ◽  
Vol 620 ◽  
pp. A17 ◽  
Author(s):  
M. Plionis ◽  
L. Koutoulidis ◽  
E. Koulouridis ◽  
L. Moscardini ◽  
C. Lidman ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Spatial Clustering ◽  
Galactic Nuclei ◽  
Point Sources ◽  
Dark Matter Halos ◽  
Sample Median ◽  
X Ray ◽  
Flux Limit ◽  
Point Correlation ◽  
Point Correlation Function

The XMM-XXL Survey spans two fields of 25 deg2 each observed for more than 6 Ms with XMM, which provided a sample of tens of thousands of point sources with a flux limit of ~2.2 × 10−15 and ~1.4 × 10−14 erg s−1 cm2, corresponding to 50% of the area curve, in the soft band (0.5–2 keV) and hard band (2–10 keV), respectively. In this paper we present the spatial clustering properties of ~3100 and ~1900 X-ray active galactic nuclei (AGNs) in the soft and hard bands, respectively, which have been spectroscopically observed with the AAOmega facility. This sample is 90% redshift complete down to an optical magnitude limit of r ≲ 21.8. The sources span the redshift interval 0 < z < 5.2, although in the current analysis we limit our samples to z ≤ 3, with corresponding sample median values of z̅ ≃ 0.96 and 0.79 for the soft band and hard band, respectively. We employ the projected two-point correlation function to infer the spatial clustering and find a correlation length r0 = 7.0(±0.34) and 6.42(±0.42) h−1 Mpc, respectively, for the soft- and hard-band detected sources with a slope for both cases of γ = 1.44(±0.1). The power-law clustering was detected within comoving separations of 1 and ~25 h−1 Mpc. These results, as well as those derived in two separate redshift ranges, provide bias factors of the corresponding AGN host dark matter halos that are consistent with a halo mass of log10[Mh∕(h−1M⊙)] = 13.04 ± 0.06, confirming the results of most recent studies based on smaller X-ray AGN samples.

Optical Counterparts of HEAO-1 X-ray Sources

1985 ◽  
Vol 6 (2) ◽  
pp. 147-151 ◽  
Author(s):  
D. A. H. Buckley ◽  
I. R. Tuohy ◽  
R. A. Remillard
Keyword(s):  
Active Galactic Nuclei ◽  
Cataclysmic Variables ◽  
Galactic Nuclei ◽  
X Ray ◽  
Preliminary Results ◽  
Sky Survey ◽  
Identification Techniques

AbstractWe present preliminary results of a search for the optical counterparts of faint but energetic (1-13 keV) X-ray sources observed by the HEAO-1 satellite. The objects we have identified include Active Galactic Nuclei, Cataclysmic Variables, Be Binaries, and RS CVn Systems. A description is also given of the identification techniques and the X-ray database, which represents the most recent flux-limited all-sky survey of hard X-ray sources.

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