- ID:
- ivo://CDS.VizieR/J/A+A/539/A48
- Title:
- XMM AGN optical-UV luminosities
- Short Name:
- J/A+A/539/A48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Active galactic nuclei (AGN) emit radiation over a wide range of wavelengths, with a peak of emission in the far-UV region of the electromagnetic spectrum, a spectral region that is historically difficult to observe. Using optical, GALEX UV, and XMM-Newton data we derive the spectral energy distribution (SED) from the optical/UV to X-ray regime of a sizeable sample of AGN. The principal motivation is to investigate the relationship between the optical/UV emission and the X-ray emission and provide bolometric corrections to the hard X-ray (2-10keV) energy range, k_bol_, the latter being a fundamental parameter in current physical cosmology.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/890/150
- Title:
- X-ray binaries in M101 with HST optical data
- Short Name:
- J/ApJ/890/150
- Date:
- 17 Jan 2022 00:32:05
- Publisher:
- CDS
- Description:
- The high-energy emission from nearby, star-forming galaxies is dominated by X-ray binaries, where a neutron star or black hole is accreting mass from either a low-mass (<~M_{sun}_) or high-mass (>~8M_{sun}_) star. Donor stars with intermediate masses ~3-7M_{sun}_ are also possible, but rarer in our Galaxy. Since it is not possible to separate low-, intermediate-, and high-mass X-ray binaries (LMXBs, IMXBs, and HMXBs) from their X-ray properties alone, we use optical images of M101 taken with the Hubble Space Telescope to directly constrain the masses of donor stars in X-ray binaries down to ~3M_{sun}_. For X-ray binaries that still live within their parent star cluster, the age of the cluster provides strong constraints on the mass of the donor and hence type of binary. We present the classification, on a source-by-source basis, of 140 X-ray point sources in the nearby spiral galaxy M101 (D=6.4+/-0.2Mpc). We find that, overall, HMXBs appear to follow the spiral arms, while LMXBs dominate the bulge region as expected, but also appear to form an inter-arm disk population. The X-ray luminosity functions for HMXBs and LMXBs are well fit by a power-law distribution, dN/dL_X_{propto}L^{alpha}^, with {alpha}=-1.71+/-0.06 (HMXBs) and {alpha}=-1.96+/-0.08 (LMXBs), and the brightest sources are consistent with the expectations from sampling statistics without requiring a physical cutoff. Overall, our results for HMXB and LMXB populations agree well with the specific star formation rate map presented for M101 recently by Lehmer and collaborators.
- ID:
- ivo://CDS.VizieR/J/ApJ/896/95
- Title:
- X-ray obs. of narrow- and broad-line Seyfert 1 gal.
- Short Name:
- J/ApJ/896/95
- Date:
- 03 Dec 2021 00:52:46
- Publisher:
- CDS
- Description:
- We present a detailed comparative systematic study using a sample of 221 narrow-line Seyfert 1 (NLSy1) galaxies in comparison to a redshift-matched sample of 154 broad-line Seyfert 1 (BLSy1) galaxies based on their observations using ROSAT and/or XMM-Newton in soft X-ray band (0.1-2.0keV). A homogeneous analysis is carried out to estimate their soft X-ray photon indices ({Gamma}_X_^s^) and its correlations with other parameters of nuclear activities such as Eddington ratios (REdd), bolometric luminosities (Lbol), black hole masses (MBH), and the widths of the broad component of H{beta} lines (FWHM(H{beta})). In our analysis, we found clear evidence of the difference in the {Gamma}_X_^s^ and R_Edd_ distributions among NLSy1 and BLSy1 galaxies, with steeper {Gamma}_X_^s^ and higher R_Edd_ for the former. Such a difference also exists in the spectral index distribution in hard X-ray ({Gamma}_X_^h^), based on the analysis of 53 NLSy1 and 46 BLSy1 galaxies in the 2-10keV energy band. The difference in REdd distributions does exist even after applying the average correction for the difference in the inclination angle of NLSy1 and BLSy1 galaxies. We also estimated R_Edd_, based on SED fitting of 34 NLSy1 and 30 BLSy1 galaxies over the 0.3-10keV energy band, and found that results are still consistent with REdd estimates based on the optical bolometric luminosity. Our analysis suggests that the higher REdd in NLSy1 is responsible for its steeper X-ray spectral slope compared to the BLSy1, consistent with the disk-corona model as proposed for the luminous AGNs.
- ID:
- ivo://CDS.VizieR/J/ApJ/734/43
- Title:
- X-ray, optical and radio monitoring of 3C 111
- Short Name:
- J/ApJ/734/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of extensive multi-frequency monitoring of the radio galaxy 3C 111 between 2004 and 2010 at X-ray (2.4-10keV), optical (R band), and radio (14.5, 37, and 230GHz) wave bands, as well as multi-epoch imaging with the Very Long Baseline Array (VLBA) at 43GHz. Over the six years of observation, significant dips in the X-ray light curve are followed by ejections of bright superluminal knots in the VLBA images. This shows a clear connection between the radiative state near the black hole, where the X-rays are produced, and events in the jet. The X-ray continuum flux and Fe line intensity are strongly correlated, with a time lag shorter than 90 days and consistent with zero.
- ID:
- ivo://CDS.VizieR/J/MNRAS/360/782
- Title:
- X-ray-selected normal galaxies
- Short Name:
- J/MNRAS/360/782
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we estimate the local (z<0.22) X-ray luminosity function of 'normal' galaxies derived from the XMM-Newton Needles in the Haystack Survey. This is an on-going project that aims to identify X-ray-selected normal galaxies (i.e. non-AGN dominated) in the local Universe. We are using a total of 70 XMM-Newton fields covering an area of 11deg^2^ which overlap with the Sloan Digital Sky Survey Data Release 2. Normal galaxies are selected on the basis of their resolved optical light profile, their low X-ray-to-optical flux ratio [log(fx/fo)<-2] and soft X-ray colours. We find a total of 28 candidate normal galaxies to the 0.58keV band flux limit of 2x10^-15^erg/cm2/s. Optical spectra are available for most sources in our sample (82 per cent). These provide additional evidence that our sources are bona fide normal galaxies with X-ray emission coming from diffuse hot gas emission and/or X-ray binaries rather than a supermassive black hole.
- ID:
- ivo://CDS.VizieR/J/ApJ/682/1020
- Title:
- X-ray sources in NGC 4194 and NGC 7541
- Short Name:
- J/ApJ/682/1020
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We examine the X-ray point-source population and 2-10keV luminosity for two galaxies with high star formation rates (SFRs), NGC 4194 and NGC 7541 and combined our results with a sample of galaxies with SFRs above 1M_{sun}_/yr.
- ID:
- ivo://CDS.VizieR/J/ApJ/788/48
- Title:
- X-ray through NIR photometry of NGC 2617
- Short Name:
- J/ApJ/788/48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- After the All-Sky Automated Survey for SuperNovae discovered a significant brightening of the inner region of NGC 2617, we began a ~70 day photometric and spectroscopic monitoring campaign from the X-ray through near-infrared (NIR) wavelengths. We report that NGC 2617 went through a dramatic outburst, during which its X-ray flux increased by over an order of magnitude followed by an increase of its optical/ultraviolet (UV) continuum flux by almost an order of magnitude. NGC 2617, classified as a Seyfert 1.8 galaxy in 2003, is now a Seyfert 1 due to the appearance of broad optical emission lines and a continuum blue bump. Such "changing look active galactic nuclei (AGNs)" are rare and provide us with important insights about AGN physics. Based on the H{beta} line width and the radius-luminosity relation, we estimate the mass of central black hole (BH) to be (4+/-1)x10^7^ M_{sun}_. When we cross-correlate the light curves, we find that the disk emission lags the X-rays, with the lag becoming longer as we move from the UV (2-3 days) to the NIR (6-9 days). Also, the NIR is more heavily temporally smoothed than the UV. This can largely be explained by a simple model of a thermally emitting thin disk around a BH of the estimated mass that is illuminated by the observed, variable X-ray fluxes.
- ID:
- ivo://CDS.VizieR/J/ApJS/245/17
- Title:
- X-shaped radio galaxies from FIRST
- Short Name:
- J/ApJS/245/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 290 "winged" or X-shaped radio galaxies (XRGs) extracted from the latest (2014 December 17) data release of the "Very Large Array Faint Images of the Radio Sky at Twenty centimeter". We have combined these radio images with their counterparts in the TIFR GMRT sky survey at 150MHz, in an attempt to identify any low surface brightness radio emission present in these sources. This has enabled us to assemble a sample of 106 "strong" XRG candidates and 184 "probable" XRG candidates whose XRG designation needs to be verified by further observations. The present sample of 290 XRG candidates is almost twice as large as the number of XRGs currently known. Twenty-five of our 290 XRG candidates (9 "strong" and 16 "probable") are identified as quasars. Double-peaked narrow emission lines are seen in the optical spectra of three of the XRG candidates (two "strong" and one "probable"). Nearly 90% of the sample is located in the FR II domain of the Owen-Ledlow diagram. A few of the strong XRG candidates have a rather flat radio spectrum (spectral index {alpha} flatter than -0.3) between 150MHz and 1.4GHz, or between 1.4 and 5GHz. Since this is not expected for lobe-dominated extragalactic radio sources (like nearly all known XRGs), these sources are particularly suited for follow-up radio imaging and near-simultaneous measurement of the radio spectrum.
- ID:
- ivo://CDS.VizieR/J/ApJ/852/48
- Title:
- "X-shaped" radio sources. II. Sample properties
- Short Name:
- J/ApJ/852/48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In an earlier paper, we presented Jansky Very Large Array multi-frequency, multi-array continuum imaging of a unique sample of low-axial ratio radio galaxies. In this paper, the second in the series, we examine the images to learn the phenomenology of how the off-axis emission relates to the main radio source. Inversion-symmetric offset emission appears to be bimodal and to originate from one of two strategic locations: outer ends of radio lobes (outer-deviation) or from inner ends (inner-deviation). The latter sources are almost always associated with edge-brightened sources. With S- and Z-shaped sources being a subset of outer-deviation sources, this class lends itself naturally to explanations involving black hole axis precession. Our data allow us to present a plausible model for the more enigmatic inner-deviation sources with impressive wings; as for outer-deviation sources these too require black hole axis shifts, although they also require plasma backflows into relic channels. Evolution in morphology over time relates the variety in structures in inner-deviation sources including XRGs. With features such as non- collinearities, central inner-S "spine," corresponding lobe emission peaks, double and protruding hotspots not uncommon, black hole axis precession, drifts, or flips could be active in a significant fraction of radio sources with prominent off-axis emission. At least 4% of radio galaxies appear to undergo black hole axis rotation. Quasars offer a key signature for recognizing rotating axes. With a rich haul of sources that have likely undergone axis rotation, our work shows the usefulness of low-axial ratio sources in pursuing searches for binary supermassive black holes.
- ID:
- ivo://CDS.VizieR/J/A+A/603/A1
- Title:
- X-shooter spectra of 6 ~2.2 quasars
- Short Name:
- J/A+A/603/A1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We studied the spectra of six z~2.2 quasars obtained with the X-shooter spectrograph at the Very Large Telescope. The redshift of these sources and X-shooter's spectral coverage allow us to cover the rest spectral range ~1200-7000{AA} for the simultaneous detection of optical and ultraviolet lines emitted by the Broad Line Region. Simultaneous measurements, avoiding issues related to quasars variability, help us understanding the connection between different Broad Line Region line profiles generally used as virial estimators of Black Holes masses in quasars. The goal of this work is comparing the emission lines from the same object to check on the reliability of H{alpha}, MgII and CIV with respect to H{beta}. H{alpha} and MgII linewidths correlate well with H{beta}, while CIV shows a poorer correlation, due to the presence of strong blueshifts and asymmetries in the profile. We compare our sample with the only other two whose spectra were taken with the same instrument and for all examined lines our results are in agreement with the ones obtained with X-shooter at z~1.5-1.7. We finally evaluate CIII] as a possible substitute of CIV in the same spectral range and find that its behaviour is more coherent with those of the other lines: we believe that, when a high quality spectrum such as the ones we present is available and a proper modelization with the FeII and FeIII emissions is performed, the use of this line is more appropriate than that of CIV if not corrected for the contamination by non-virialized components.