The stellar content of the XMM-Newton bright serendipitous survey

López‐Santiago, J.; Micela, G.; Sciortino, S.; Favata, F.; Caccianiga, A.; Ceca, R. Della; Severgnini, P.; Braito, V.

doi:10.1051/0004-6361:20065696

Cited by 38 publications

(44 citation statements)

References 54 publications

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“…The optical and X-ray properties of the Galactic population are discussed in López-Santiago et al (2007). Previous X-rays spectral analyses of parts of the XBS sample have already been reported in previous works.…”

Section: The Xbs Agn Samplementioning

confidence: 90%

The X-ray spectral properties of the AGN population in theXMM-Newtonbright serendipitous survey

Corral

Ceca

Caccianiga

et al. 2011

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Context. X-ray surveys are a key instrument in the study of active galactic nuclei (AGN). Thanks to their penetrating ability, X-rays are able to map the innermost regions close to the central super massive black hole (SMBH) as well as to detect and characterize its emission up to high redshift. Aims. We present here a detailed X-ray spectral analysis of the AGN belonging to the XMM-Newton bright survey (XBS). The XBS is composed of two flux-limited samples selected in the complementary 0.5−4.5 and 4.5−7.5 keV energy bands and comprising more than 300 AGN up to redshift ∼2.4. Methods. We performed an X-ray analysis following two different approaches: by analyzing individually each AGN X-ray spectrum and by constructing average spectra for different AGN types. Results. From the individual analysis, we find that there seems to be an anti correlation between the spectral index and the sources' hard X-ray luminosity, such that the average photon index for the higher luminosity sources (>10 44 erg s −1 ) is significantly (>2σ) flatter than the average for the lower luminosity sources. We also find that the intrinsic column density distribution agrees with AGN unified schemes, although a number of exceptions are found (3% of the whole sample), which are much more common among optically classified type 2 AGN. We also find that the so-called "soft-excess", apart from the intrinsic absorption, constitutes the principal deviation from a power-law shape in AGN X-ray spectra and it clearly displays different characteristics, and likely a different origin, for unabsorbed and absorbed AGN. Regarding the shape of the average spectra, we find that it is best reproduced by a combination of an unabsorbed (absorbed) power law, a narrow Fe Kα emission line and a small (large) amount of reflection for unabsorbed (absorbed) sources. We do not significantly detect any relativistic contribution to the line emission and we compute an upper limit for its equivalent width (EW) of 230 eV at the 3σ confidence level. Finally, by dividing the type 1 AGN sample into high-and low-luminosity sources, we marginally detect a decrease in the narrow Fe Kα line EW and in the amount of reflection as the luminosity increases, the "so-called" Iwasawa-Taniguchi effect.

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Section: The Xbs Agn Samplementioning

confidence: 90%

The X-ray spectral properties of the AGN population in theXMM-Newtonbright serendipitous survey

Corral

Ceca

Caccianiga

et al. 2011

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130

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“…In general, the coronal plasma exhibits a temperature gradient that cannot be studied using low-resolution X-ray spectra (although see Robrade & Schmitt 2005). Nevertheless, it has been shown that the dual-temperature nature of the fits may represent an intrinsic property of the coronal spectra of moderately active late-K and M stars (Schmitt et al 1990;Briggs & Pye 2003;López-Santiago et al 2007). In this scenario, the third (higher) temperature required to fit the hard tail of the X-ray spectrum is understood to be present only during flare-like events.…”

Section: General Propertiesmentioning

confidence: 99%

DeepXMM-Newtonobservation of theη Chamaleontis cluster

López‐Santiago

Colombo

López-García

2010

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Context. The members of the η Chamaleontis cluster are in an evolutionary stage in which disks are rapidly evolving. It also exhibits some peculiarities, such as the large fraction of binaries and accretion disks, probably related to the cluster formation process. Its proximity makes this stellar group an ideal target for studying the relation between X-ray emission and those stellar parameters. Aims. Our main objective is to determine the general X-ray properties of the cluster members in terms of coronal temperature, column density, emission measure, X-ray luminosity, and variability. We also aim to establish the relation between the X-ray luminosity of these stars and other stellar parameters, such as effective temperature, binarity, and the presence of accretion disks. Finally, a study of flare energies in each flare event detected during the observations and their relation with some stellar parameters is also performed. Methods. We used proprietary data from a deep XMM-Newton EPIC observation targeting the core of the η Chamaleontis cluster. Specific software for the reduction of XMM-Newton data was used to analyze our observation. To detect sources in the composed EPIC pn+mos image, we used the wavelet-based code PWDetect. General coronal properties were derived from plasma model fitting. X-ray light curves in the 0.3−8.0 keV energy range were generated for each star. Results. We determine both the coronal properties and variability of the η Chamaleontis members in the XMM-Newton EPIC field-ofview. A total of six flare-like events are clearly detected in five different stars. For them, we derived coronal properties during the flare events and pseudo-quiescent state separately. In our observations, stars that experienced a flare event have higher X-ray luminosities in the pseudo-quiescent state than cluster members of similar spectral type that exhibit no evidence of flaring independently of whether they have an accretion disk or not. Observed flare energies are typical of both pre-main-and main-sequence M stars. We detected no difference between flare energies of stars with and without an accretion disk.

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“…Because of this and their ubiquity, late-type stars are excellent tracers of the Galactic potential (Bochanski et al 2007). Distinguishing between young and old stars is then crucial to an understanding of the kinematics of the Galaxy and of stellar formation history in our neighborhood (López-Santiago et al 2007). …”

Section: Introductionmentioning

confidence: 99%

“…In this new era of Virtual Observatory and extensive photometric databases and catalogs, the compilation of spectroscopic data is important for the purpose of constraining the properties of different astronomical objects, in particular, of stars (e.g. Sciortino et al 1995;Takeda et al 2007;Micela et al 2007;López-Santiago et al 2007;Klutsch et al 2008;López-Santiago et al 2009). The utility of substantial spectroscopic compilations has been demonstrated in the past by various groups.…”

Section: Introductionmentioning

confidence: 99%

A high-resolution spectroscopic survey of late-type stars: chromospheric activity, rotation, kinematics, and age

López‐Santiago¹,

Montes²,

Galvez-Ortiz

et al. 2010

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100

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Aims. We present a compilation of spectroscopic data from a survey of 144 chromospherically active young stars in the solar neighborhood, which may be used to investigate different aspects of its formation and evolution in terms of kinematics and stellar formation history. The data have already been used by us in several studies. With this paper, we make all these data accessible to the scientific community for future studies on different topics. Methods. We performed spectroscopic observations with echelle spectrographs to cover the entirety of the optical spectral range simultaneously. Standard data reduction was performed with the IRAF echelle package. We applied the spectral subtraction technique to reveal chromospheric emission in the stars of the sample. The equivalent width of chromospheric emission lines was measured in the subtracted spectra and then converted to fluxes using equivalent width-flux relationships. Radial and rotational velocities were determined by the cross-correlation technique. Kinematics, equivalent widths of the lithium line λ6707.8 Å and spectral types were also determined. Results. A catalog of spectroscopic data is compiled: radial and rotational velocities, space motion, equivalent widths of optical chromospheric activity indicators from Ca ii H & K to the calcium infrared triplet and the lithium line in λ6708 Å. Fluxes in the chromospheric emission lines and R HK are also determined for each observation of a star in the sample. We used these data to investigate the emission levels of our stars. The study of the Hα emission line revealed two different populations of chromospheric emitters in the sample, clearly separated in the log F Hα /F bol − (V − J) diagram. The dichotomy may be associated with the age of the stars.

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The stellar content of the XMM-Newton bright serendipitous survey

Cited by 38 publications

References 54 publications

The X-ray spectral properties of the AGN population in theXMM-Newtonbright serendipitous survey

The X-ray spectral properties of the AGN population in theXMM-Newtonbright serendipitous survey

DeepXMM-Newtonobservation of theη Chamaleontis cluster

A high-resolution spectroscopic survey of late-type stars: chromospheric activity, rotation, kinematics, and age

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