Linear Regression for Astronomical Data with Measurement Errors and Intrinsic Scatter

Akritas, Michaël G.; Bershady, Matthew A.

doi:10.1086/177901

Cited by 796 publications

(905 citation statements)

References 21 publications

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“…Figure 11 shows ICM temperature plotted against luminosity for all sources in the z0.1 and ERA samples with temperatures obtained by spectral analysis. We used the orthogonal BCES method from Akritas & Bershady (1996) to calculate the regression line (solid line, log10LX = (3.56 ± 0.36)log10TX + (42.40 ± 0.15)).…”

Section: Comparison With General Cluster and Group Environmentsmentioning

confidence: 99%

The link between accretion mode and environment in radio-loud active galaxies

Ineson

Croston

Hardcastle

et al. 2015

Mon. Not. R. Astron. Soc.

130

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The interactions between radio-loud AGN and their environments play an important rôle in galaxy and cluster evolution. Recent work has demonstrated fundamental differences between High and Low Excitation Radio Galaxies (HERGs and LERGs), and shown that they may have different relationships with their environments. In the Chandra Large Project ERA (Environments of Radio-loud AGN), we made the first systematic X-ray environmental study of the cluster environments of radio galaxies at a single epoch (z ∼ 0.5), and found tentative evidence for a correlation between radio luminosity and cluster X-ray luminosity. We also found that this relationship appeared to be driven by the LERG sub-population (Ineson et al. 2013).We have now repeated the analysis with a low redshift sample (z ∼ 0.1), and found strong correlations between radio luminosity and environment richness and between radio luminosity and central density for the LERGs but not for the HERGs. These results are consistent with models in which the HERGs are fuelled from accretion discs maintained from local reservoirs of gas, while LERGs are fuelled more directly by gas ingested from the intra-cluster medium.Comparing the samples, we found that although the maximum environment richness of the HERG environments is similar in both samples, there are poorer HERG environments in the z ∼ 0.1 sample than in the z ∼ 0.5 sample. We have therefore tentative evidence of evolution of the HERG environments. We found no differences between the LERG subsamples for the two epochs, as would be expected if radio and cluster luminosity are related.

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Section: Comparison With General Cluster and Group Environmentsmentioning

confidence: 99%

The link between accretion mode and environment in radio-loud active galaxies

Ineson

Croston

Hardcastle

et al. 2015

Mon. Not. R. Astron. Soc.

130

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“…Ignoring these outliers, we performed a linear regression between their logarithms to convert L cat, 0.5−2.0 to L ap, bol for the 185 clusters without proper spectral fit. The best-fit linear relation derived using the BCES orthogonal regression method (Akritas & Bershady 1996) is represented by the dashed line in Fig. 15 and is given by Eq.…”

Section: Cluster Sample With X-ray Flux From the 2xmmi-dr3 Cataloguementioning

confidence: 99%

“…Figure 23 shows the relation between the measured X-ray bolometric luminosity, L 500 , modified with the evolution parameter for self-similar evolution and the X-ray aperture temperature, T ap . We used the BCES orthogonal regression method (Akritas & Bershady 1996) to derive the best-fit linear relation between the logarithms of L 500 and T ap taking into account their errors as well as the intrinsic scatter. The best fit is shown in Fig.…”

Section: X -T Relation Of the Full Samplementioning

confidence: 99%

The 2XMMi/SDSS Galaxy Cluster Survey

Takey

Schwope

Lamer

2013

A&A

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Aims. We compile a sample of X-ray-selected galaxy groups and clusters from the XMM-Newton serendipitous source catalogue (2XMMi-DR3) with optical confirmation and redshift measurement from the Sloan Digital Sky Survey (SDSS). We present an analysis of the X-ray properties of this new sample with particular emphasis on the X-ray luminosity-temperature (L X − T ) relation. Methods. The X-ray cluster candidates were selected from the 2XMMi-DR3 catalogue in the footprint of the SDSS-DR7. We developed a finding algorithm to search for overdensities of galaxies at the positions of the X-ray cluster candidates in the photometric redshift space and to measure the redshifts of the clusters from the SDSS data. For optically confirmed clusters with good quality X-ray data we derived the X-ray flux, luminosity, and temperature from proper spectral fits, while the X-ray flux for clusters with low-quality X-ray data was obtained from the 2XMMi-DR3 catalogue. Results. The detection algorithm provides the photometric redshift of 530 galaxy clusters. Of these, 310 clusters have a spectroscopic redshift for at least one member galaxy. About 75 percent of the optically confirmed cluster sample are newly discovered X-ray clusters. Moreover, 301 systems are known as optically selected clusters in the literature while the remainder are new discoveries in X-ray and optical bands. The optically confirmed cluster sample spans a wide redshift range 0.03−0.70 (median z = 0.32). In this paper, we present the catalogue of X-ray-selected galaxy groups and clusters from the 2XMMi/SDSS galaxy cluster survey. The catalogue has two subsamples: (i) a cluster sample comprising 345 objects with their X-ray spectroscopic temperature and flux from the spectral fitting; and (ii) a cluster sample consisting of 185 systems with their X-ray flux from the 2XMMi-DR3 catalogue, because their X-ray data are insufficient for spectral fitting. For each cluster, the catalogue also provides the X-ray bolometric luminosity and the cluster mass at R 500 based on scaling relations and the position of the likely brightest cluster galaxy (BCG). The updated L X − T relation of the current sample with X-ray spectroscopic parameters is presented. We found the slope of the L X − T relation to be consistent with published ones. We see no evidence for evolution in the slope and intrinsic scatter of the L X − T relation with redshift when excluding the low-luminosity groups.

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“…The fits were undertaken using linear regression in the log-log plane, taking the uncertainties in both variables into account, and the scatter was computed as described in Pratt et al (2009) andPlanck Collaboration (2011f). The fitting procedure used the BCES orthogonal regression method (Akritas & Bershady 1996). In addition to fitting with the slope and normalisation free, we also investigated the scaling relations obtained with the slope fixed to the self-similar values.…”

Section: Fitting Proceduresmentioning

confidence: 99%

Planckintermediate results

Ade¹,

Aghanim²,

Arnaud³

et al. 2013

A&A

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We examine the relation between the galaxy cluster mass M and Sunyaev-Zeldovich (SZ) effect signal D 2 A Y 500 for a sample of 19 objects for which weak lensing (WL) mass measurements obtained from Subaru Telescope data are available in the literature. Hydrostatic X-ray masses are derived from XMM-Newton archive data, and the SZ effect signal is measured from Planck all-sky survey data. We find an M WL −D 2 A Y 500 relation that is consistent in slope and normalisation with previous determinations using weak lensing masses; however, there is a normalisation offset with respect to previous measures based on hydrostatic X-ray mass-proxy relations. We verify that our SZ effect measurements are in excellent agreement with previous determinations from Planck data. For the present sample, the hydrostatic X-ray masses at R 500 are on average ∼20 percent larger than the corresponding weak lensing masses, which is contrary to expectations. We show that the mass discrepancy is driven by a difference in mass concentration as measured by the two methods and, for the present sample, that the mass discrepancy and difference in mass concentration are especially large for disturbed systems. The mass discrepancy is also linked to the offset in centres used by the X-ray and weak lensing analyses, which again is most important in disturbed systems. We outline several approaches that are needed to help achieve convergence in cluster mass measurement with X-ray and weak lensing observations.

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Linear Regression for Astronomical Data with Measurement Errors and Intrinsic Scatter

Cited by 796 publications

References 21 publications

The link between accretion mode and environment in radio-loud active galaxies

The link between accretion mode and environment in radio-loud active galaxies

The 2XMMi/SDSS Galaxy Cluster Survey

Planckintermediate results

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