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Resource Record Summary

Catalog Service:
CHAMP/SDSS Nearby Low-Luminosity AGN Catalog

Short name: CHAMPSDSSA
IVOA Identifier: ivo://nasa.heasarc/champsdssaPublisher: NASA/GSFC HEASARCivo://nasa.heasarc/ASD[Pub. ID]
More Info: https://heasarc.gsfc.nasa.gov/W3Browse/all/champsdssa.html
VO Compliance: Level 2: This is a VO-compliant resource.
Status: active
Registered: 2024 May 17 00:00:00Z
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Description


The combination of the Sloan Digital Sky Survey (SDSS) and the Chandra Multiwavelength Project (ChaMP; Green et al. 2004, ApJS, 150, 43) currently offers the largest and most homogeneously selected sample of nearby galaxies for investigating the relations between X-ray nuclear emission, nebular line emission, black hole masses, and the properties of the associated stellar populations. The authors provide X-ray spectral fits and valid uncertainties for all the galaxies with counts ranging from 2 to 1325 (mean 76, median 19). They present in their paper novel constraints that both X-ray luminosity L<sub>X</sub> and X-ray spectral energy distribution bring to the galaxy evolutionary sequence HII -> Seyfert/Transition Object -> LINER -> Passive suggested by optical data. In particular, the authors show that both L<sub>X</sub> and Gamma, the slope of the power law that best fits the 0.5 - 8 keV spectra, are consistent with a clear decline in the accretion power along the sequence, corresponding to a softening of their spectra. This implies that, at z ~ 0, or at low-luminosity active galactic nucleus (AGN) levels, there is an anticorrelation between Gamma and L/L<sub>Edd</sub>, opposite to the trend which is exhibited by high-z AGN (quasars). The turning point in the Gamma - L/L<sub>Edd</sub> LLAGN + quasars relation occurs near Gamma ~ 1.5 and L/L<sub>Edd</sub> ~ 0.01. Interestingly, this is identical to what stellar mass X-ray binaries exhibit, indicating that the authors have probably found the first empirical evidence for an intrinsic switch in the accretion mode, from advection-dominated flows to standard (disk/corona) accretion modes in supermassive black hole accretors, similar to what has been seen and proposed to happen in stellar mass black hole systems. The anticorrelation the authors find between Gamma and L/L<sub>Edd</sub> may instead indicate that stronger accretion correlates with greater absorption. Therefore, the trend for softer spectra toward more luminous, high-redshift, and strongly accreting (L/L<sub>Edd</sub> >~ 0.01) AGNs/quasars could simply be the result of strong selection biases reflected in the dearth of type 2 quasar detections. The cross-match of all ChaMP sky regions imaged by Chandra/ACIS with the SDSS DR4 spectroscopic footprint results in a parent sample of 15,955 galaxies on or near a chip and a subset of 199 sources that are X-ray detected. Among those, only 107 sources have an off-axis angle (OAA) Theta <0.2 degrees and avoid ccd=8 due to high serial readout noise; these 107 objects comprise the main sample that the authors employ for this study and that are listed in this table. The authors performed direct spectral fits to the X-ray counts distribution using the full instrument calibration, known redshift, and Galactic 21-cm column nH<sub>Gal</sub>. Source spectra were extracted from circular regions with radii corresponding to energy encircled fractions of ~90%, while the background region encompasses a 20 arcsec annulus, centered on the source, with separation 4 arcsecs, from the source region. Any nearby sources were excised, from both the source and the background regions. The spectral fitting was done via yaxx ('Yet Another X-ray eXtractor': Aldcroft 2006, BAAS, 38, 376), an automated script that employs the CIAO Sherpa tool. Each spectrum was fitted in the range 0.5 - 8 keV by two different models: (1) a single power law plus absorption fixed at the Galactic 21-cm value (model 'PL'), and (2) a fixed power law of photon index Gamma = 1.9 plus intrinsic absorption of column nH (model 'PLfix'). For the nine objects with more than 200 counts, the authors employed a third model in which both the slope of the power law and the intrinsic absorption were free to vary (model 'PL_abs'). This table was created by the HEASARC in January 2012 based on CDS Catalog J/ApJ/705/1336/ file table1.dat. This is a service provided by NASA HEASARC .

More About this Resource

About the Resource Providers

This section describes who is responsible for this resource

Publisher: NASA/GSFC HEASARCivo://nasa.heasarc/ASD[Pub. ID]

Creator: Constantin et al. Contributor:

Contact Information:
X NASA/GSFC HEASARC help desk
Email:

Status of This Resource

This section provides some status information: the resource version, availability, and relevant dates.

Version: n/a
Availability: This is an active resource.
  • This service apparently provides only public data
Relevant dates for this Resource:
  • Representative: 2024 May 17

This resource was registered on: 2024 May 17 00:00:00Z
This resource description was last updated on: 2024 May 17 00:00:00Z

What This Resource is About

This section describes what the resource is, what it contains, and how it might be relevant.

Resource Class: CatalogService
This resource is a service that provides access to catalog data. You can extract data from the catalog by issuing a query, and the matching data is returned as a table.
Resource type keywords:
  • Catalog
Subject keywords:
  • Survey Source
This service provides data from:
  • facility: SDSS
Intended audience or use:
  • Research: This resource provides information appropriate for supporting scientific research.
More Info: https://heasarc.gsfc.nasa.gov/W3Browse/all/champsdssa.html Literature Reference: 2009ApJ...705.1336C

Related Resources:

Services that provide access to data in this resource:
HEASARC TAP ivo://nasa.heasarc/services/xamin [Res. ID]

Data Coverage Information

This section describes the data's coverage over the sky, frequency, and time.

Reference Coordinate System: UTC-ICRS-TOPOXXivo://STClib/CoordSys#UTC-ICRS-TOPO[Res. ID]

Sky Coverage: Regions covered:

  • All-sky: The data from this resource is distributed over the entire sky.
Typical Size Scale (Region of Regard): , 0.0166666666666667 deg

Wavebands covered:

  • X-ray

Available Service Interfaces

Simple Cone SearchXXSearch Me

This is a standard IVOA service that takes as input a position in the sky and a radius and returns catalog records with positions within that radius.

VO Compliance: Level 2: This is a VO-compliant resource.
Available endpoints for the standard interface:
  • https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=champsdssa&
Maximum search radius accepted: 180 degrees
Maximum number of matching records returned: 99999
This service supports the VERB input parameter:
Use VERB=1 to minimize the returned columns or VERB=3 to maximize.
Table Access Protocol - Auxiliary ServiceXX

This is a standard IVOA service that takes as input an ADQL or PQL query and returns tabular data.

VO Compliance: Level 2: This is a VO-compliant resource.
Available endpoints for the standard interface:
  • https://heasarc.gsfc.nasa.gov/xamin/vo/tap
Custom Service

This is service that does not comply with any IVOA standard but instead provides access to special capabilities specific to this resource.

VO Compliance: Level 2: This is a VO-compliant resource.
Available endpoints for this service interface:
  • URL-based interface: https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=champsdssa
Custom Service

This is service that does not comply with any IVOA standard but instead provides access to special capabilities specific to this resource.

VO Compliance: Level 2: This is a VO-compliant resource.
Available endpoints for this service interface:


Developed with the support of the National Science Foundation
under Cooperative Agreement AST0122449 with the Johns Hopkins University
The NAVO project is a member of the International Virtual Observatory Alliance

This NAVO Application is hosted by the Space Telescope Science Institute

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