- ID:
- ivo://CDS.VizieR/J/A+A/642/A150
- Title:
- Quasars as standard candles. III.
- Short Name:
- J/A+A/642/A150
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalogue of ~2400 optically selected quasars with spectroscopic redshifts and X-ray observations from either Chandra or XMM-Newton. The sample can be used to investigate the non-linear relation between the UV and X-ray luminosity of quasars, and to build a Hubble diagram up to redshift z~7.5. We selected sources that are neither reddened by dust in the optical/UV nor obscured by gas in the X-rays, and whose X-ray fluxes are free from flux-limit related biases. After checking for any possible systematics, we confirm, in agreement with our previous works, that (i) the X-ray to UV relation provides distance estimates matching those from supernovae up to z~1.5, and (ii) its slope shows no redshift evolution up to z~5. We provide a full description of the methodology for testing cosmological models, further supporting a trend whereby the Hubble diagram of quasars is well reproduced by the standard flat LambdaCDM model up to z~1.5-2, but strong deviations emerge at higher redshifts. Since we have minimized all non-negligible systematic effects, and proven the stability of the Lx-Lo relation at high redshifts, we conclude that an evolution of the expansion rate of the Universe should be considered as a possible explanation for the observed deviation, rather than some systematic (redshift-dependent) effect associated with high-redshift quasars.
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- ID:
- ivo://CDS.VizieR/J/AJ/123/578
- Title:
- Quasars in the Coma cluster
- Short Name:
- J/AJ/123/578
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the second paper of the series about our Multiwavelength Quasar Survey. We present the observational results for the X-ray candidates in the field of the Coma Cluster. Nine new X-ray active galactic nuclei are discovered.
- ID:
- ivo://CDS.VizieR/J/ApJ/833/284
- Title:
- Quasi-periodic pulsations in solar flares
- Short Name:
- J/ApJ/833/284
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The nature of quasi-periodic pulsations (QPP) in solar flares is poorly constrained, and critically the general prevalence of such signals in solar flares is unknown. Therefore, we perform a large-scale search for evidence of signals consistent with QPP in solar flares, focusing on the 1-300s timescale. We analyze 675 M- and X-class flares observed by the Geostationary Operational Environmental Satellite (GOES) series in 1-8 A soft X-rays between 2011 February 1 and 2015 December 31. Additionally, over the same era we analyze Fermi/Gamma-ray Burst Monitor (GBM) 15-25keV X-ray data for each of these flares associated with a Fermi/GBM solar flare trigger, a total of 261 events. Using a model comparison method, we determine whether there is evidence for a substantial enhancement in the Fourier power spectrum that may be consistent with a QPP signature, based on three tested models; a power-law plus a constant, a broken power-law plus constant, and a power-law-plus-constant with an additional QPP signature component. From this, we determine that ~30% of GOES events and ~8% of Fermi/GBM events show strong signatures consistent with classical interpretations of QPP. For the remaining events either two or more tested models cannot be strongly distinguished from each other, or the events are well-described by single power-law or broken power-law Fourier power spectra. For both instruments, a preferred characteristic timescale of ~5-30s was found in the QPP-like events, with no dependence on flare magnitude in either GOES or GBM data. We also show that individual events in the sample show similar characteristic timescales in both GBM and GOES data sets. We discuss the implications of these results for our understanding of solar flares and possible QPP mechanisms.
- ID:
- ivo://CDS.VizieR/J/AJ/125/1537
- Title:
- QUIRC Chandra sources in OMC 2/3
- Short Name:
- J/AJ/125/1537
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We conducted deep near-infrared (NIR) imaging observations of Orion molecular clouds 2 and 3 using the Quick Infrared Camera on the 88 inch (2.2m) telescope of the University of Hawaii. Our purposes were (1) to generate a comprehensive NIR source catalog of these star-forming clouds and (2) to identify the NIR counterpart of the Chandra X-ray sources that have no counterpart in the Two Micron All Sky Survey (2MASS) catalog. Our J-, H-, and K-band observations are ~2mag deeper than those of 2MASS and match the current Chandra observation well. We detected 1448 NIR sources, for which we derived the position, the J-, H-, and K-band magnitude, and the 2MASS counterpart. Using this catalog, we identified the NIR counterpart for ~42% of the 2MASS unidentified Chandra sources. The nature of these Chandra sources are discussed using their NIR colors and spatial distributions, and a dozen protostar and brown dwarf candidates are identified.
- ID:
- ivo://CDS.VizieR/J/ApJ/896/70
- Title:
- Radial acceleration relation in CLASH galaxy clusters
- Short Name:
- J/ApJ/896/70
- Date:
- 03 Dec 2021 13:12:15
- Publisher:
- CDS
- Description:
- The radial acceleration relation (RAR) in galaxies describes a tight empirical scaling law between the total acceleration g_tot_(r)=GM_tot_(<r)/r^2^ observed in galaxies and that expected from their baryonic mass g_bar_(r)=GM_bar_(<r)/r^2^, with a characteristic acceleration scale of g_{dagger}_~1.2x10^-10^m/s^2^. Here, we examine if such a correlation exists in galaxy clusters using weak-lensing, strong-lensing, and X-ray data sets available for 20 high-mass clusters targeted by the Cluster Lensing And Supernova survey with Hubble (CLASH). By combining our CLASH data with stellar mass estimates for the brightest cluster galaxies (BCGs) and accounting for the stellar baryonic component in clusters, we determine, for the first time, an RAR on BCG-cluster scales. The resulting RAR is well described by a tight power-law relation, g_tot_{propto}g_bar_^0.51-0.05+0.04^, with lognormal intrinsic scatter of 14.7_-2.8_^+2.9^%. The slope is consistent with the low acceleration limit of the RAR in galaxies, g_tot_=(g_{dagger}_,g_bar_)^0.5^, whereas the intercept implies a much higher acceleration scale of g_{dagger}_=(2.02+/-0.11)x10^-9^m/s^2^, indicating that there is no universal RAR that holds on all scales from galaxies to clusters. We find that the observed RAR in CLASH clusters is consistent with predictions from a semianalytical model developed in the standard {Lambda}CDM framework. Our results also predict the presence of a baryonic Faber-Jackson relation ({sigma}_v^4^{propto}M_bar_) on cluster scales.
- ID:
- ivo://CDS.VizieR/J/A+A/454/301
- Title:
- Radial velocities of 6 binaries
- Short Name:
- J/A+A/454/301
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radial velocity measurements of the two components of three new discovered SB2 systems, HD183957, BD+15 4538, and BD+33 4462, have been obtained from optical spectra acquired with both ELODIE and AURELIE spectrographs at the Observatoire de Haute-Provence (OHP) and FRESCO spectrograph at the Osservatorio Astrofisico di Catania (OAC) by means of the cross-correlation technique (Tables 2-4). Radial velocities of three new discovered SB1 systems, HD 237215, HD 57267, and BD+38 2140, obtained with the same instruments are reported in Tables 5-7.
- ID:
- ivo://CDS.VizieR/J/A+A/377/925
- Title:
- Radial velocity curves of Vela X-1
- Short Name:
- J/A+A/377/925
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper the mass of the neutron star in Vela X-1 is determined, by measuring the radial velocity curve of its B supergiant companion. The tables (appendix of the paper), which list the log of observations, and the derived radial velocities, of the blue Coude Echelle Spectrograph (CES) spectra (Table A1), the red CES spectra (Table A2), and the IUE spectra (Table A3).
- ID:
- ivo://CDS.VizieR/J/ApJ/645/890
- Title:
- Radio and X-ray-emitting broad-line AGNs
- Short Name:
- J/ApJ/645/890
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derived the black hole fundamental plane relationship between the 1.4GHz radio luminosity (Lr), 0.1-2.4keV X-ray luminosity (LX), and black hole mass (M) from a uniform broad-line SDSS AGN sample including both radio-loud and radio-quiet X-ray-emitting sources. We found in our sample that the fundamental plane relation has a very weak dependence on the black hole mass, and a tight correlation also exists between the Eddington-luminosity-scaled X-ray and radio luminosities for the radio-quiet subsample. In addition, we noticed that the radio-quiet and radio-loud AGNs have different power-law slopes in the radio-X-ray nonlinear relationship. The radio-loud sample displays a slope of 1.39, which seems consistent with the jet-dominated X-ray model. However, it may also be partly due to the relativistic beaming effect. For the radio-quiet sample the slope of the radio-X-ray relationship is about 0.85, which is possibly consistent with the theoretical prediction from the accretion-flow-dominated X-ray model. We briefly discuss the reason why our derived relationship is different from some previous works and expect the future spectral studies in radio and X-ray bands on individual sources in our sample to confirm our result.
- ID:
- ivo://CDS.VizieR/J/ApJ/688/826
- Title:
- Radio and X-ray-emitting broad-line AGNs
- Short Name:
- J/ApJ/688/826
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use a recently released SDSS catalog of X-ray-emitting AGNs in conjunction with the FIRST radio survey to investigate the black hole (BH) fundamental plane relationship between the 1.4GHz radio luminosity (L_r_), 0.1-2.4keV X-ray luminosity (L_X_), and black hole mass (M), namely, logL_r_={xi}_RX_logL_X_+{xi}_RM_logM+constant. For this purpose, we compile a large sample of 725 broad-line AGNs, which consists of 498 radio-loud sources and 227 radio-quiet sources. We confirm that radio-loud objects have a steeper slope ({xi}_RX_) with respect to radio-quiet objects and that the dependence of the BH fundamental plane on the BH mass ({xi}_RM_) is weak.
- ID:
- ivo://CDS.VizieR/J/A+AS/127/119
- Title:
- Radio continuum study of the MC
- Short Name:
- J/A+AS/127/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- By comparing Parkes telescope radio surveys with the X-ray ROSAT All-Sky Survey (RASS) we have found 71 discrete sources of both radio and X-ray emission in the Large Magellanic Cloud (LMC). These 71 sources are mainly supernova remnants (SNRs) and SNR candidates (36), and background sources (27). For six of the sources we have no proposed identification and the other two are HII regions. A source-intensity comparison of the radio and X-ray sources shows very little correlation, but we note that the strongest SNRs at both radio and X-ray frequencies are young SNRs from Population I. Six new LMC SNR candidates are proposed. From the radio flux density of the SNRs we have estimated the SNR birth rate to be one every 100 (+/-20) yr and the star-formation rate (SFR) to be 0.7 (+/-0.2)M_{sun}_/yr. A similar comparison was undertaken for the Small Magellanic Cloud (SMC), but instead of the RASS we used a roster of pointed observations made with the ROSAT Position Sensitive Proportional Counter (PSPC). This comparison resulted in 27 sources in common between the Parkes radio and ROSAT PSPC surveys. Two new SMC sources are proposed for SNR candidates. The SMC SNR birth rate was estimated to be one every 350 (+/-70)yr and the SFR was estimated to be 0.15 (+/-0.05)M_{sun}_/yr.