Galactic X‐ray surveys

Ebisawa, Ken; Yamauchi, Shigeo; Bamba, Aya; Ueno, Masaru; Senda, Atsushi

doi:10.1002/asna.200310014

Cited by 3 publications

(8 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For the rest, the median is HR = 0.11, so the "medium" and the "hard" sources are defined as those with −0.59 < HR ≤ 0.10 and 0.1 < HR, respectively. Excluding the sources obviously associated with the extended structure CXOU J184357-035441 (Ueno et al 2003), number of the soft, medium and hard sources we have detected is 136, 65 and 69, respectively (Table 3). Also, we plot the locations of the soft, medium and hard Chandra sources on the 2MASS image with different colors (Fig.…”

Section: Nir Identification and Source Classificationmentioning

confidence: 97%

“…The total area of the observed field is ∼ 250 arcmin 2 . Detailed spatial and spectral study of AX J1843.8-0352 using both AO1 and AO2 observations was already published in Ueno et al (2003).…”

Section: X-ray Observation and Data Reductionmentioning

confidence: 99%

“…)= (18 : 43 : 57, −3 • 54 ′ 48 ′′ ) seem to be parts of a single extended feature, which is designated as CXOU J184357-035441 by Ueno et al (2003). This extended feature has a characteristic thermal spectrum (Ueno et al 2003), and is probably a blob associated with the supernova remnant AX J 1843.8-0352/G28.6-0.1 (Bamba et al 2001). All the other sources are consistent with the Chandra point spread function, thus they are considered as point sources.…”

Section: X-ray Point Source Extractionmentioning

confidence: 99%

“…ASCA's point source sensitivity was limited by source confusion due to its moderate X-ray mirror point spread function (∼ 1 ′ ). ASCA discovered more than two hundreds new X-ray sources on the Galactic plane region within the longitudes of |l| ≤ 45 • (Yamauchi et al 2002;Ebisawa et al 2003). Many of them are heavily absorbed and not detected in soft X-ray bands.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

ChandraDeep X‐Ray Observation of a Typical Galactic Plane Region and Near‐Infrared Identification

Ebisawa

Tsujimoto

Paizis

et al. 2005

ApJ

Self Cite

104

159

View full text Add to dashboard Cite

Using the Chandra Advanced CCD Imaging Spectrometer Imaging array (ACIS-I), we have carried out a deep hard X-ray observation of the Galactic plane region at (l, b) ≈ (28. • 5, 0. • 0), where no discrete X-ray source had been reported previously. We have detected 274 new point X-ray sources (4 σ confidence) as well as strong Galactic diffuse emission within two partially overlapping ACIS-I fields (∼ 250 arcmin 2 in total). The point source sensitivity was 1 code 662, NASA/GSFC, ∼ 3 × 10 −15 erg s −1 cm −2 in the hard X-ray band (2 -10 keV) and ∼ 2 × 10 −16 erg s −1 cm −2 in the soft band (0.5 -2 keV). Sum of all the detected point source fluxes accounts for only ∼ 10 % of the total X-ray flux in the field of view. Even hypothesizing a new population of much dimmer and numerous Galactic point sources, the total observed X-ray flux cannot be explained. Therefore, we conclude that X-ray emission from the Galactic plane has truly diffuse origin. Removing point sources brighter than ∼ 3 × 10 −15 erg s −1 cm −2 (2-10 keV), we have determined the Galactic diffuse X-ray flux as 6.5 ×10 −11 erg s −1 cm −2 deg −2 (2-10 keV). Only 26 point sources were detected both in the soft and hard bands, indicating that there are two distinct classes of the X-ray sources distinguished by the spectral hardness ratio. Surface number density of the hard sources is only slightly higher than that measured at the high Galactic latitude regions, indicating that majority of the hard sources are background AGNs. Following up the Chandra observation, we have performed a near-infrared (NIR) survey with SOFI at ESO/NTT. Almost all the soft X-ray sources have been identified in NIR and their spectral types are consistent with main-sequence stars, suggesting most of them are nearby X-ray active stars. On the other hand, only 22 % of the hard sources had NIR counterparts, which are presumably Galactic. From X-ray and NIR spectral study, they are most likely to be quiescent cataclysmic variables. Our observation suggests a population of 10 4 cataclysmic variables in the entire Galactic plane fainter than ∼ 2 × 10 33 erg s −1 . We have carried out a precise spectral study of the Galactic diffuse X-ray emission excluding the point sources. Confirming previous results, we have detected prominent emission lines from highly ionized heavy elements in the diffuse emission. In particular, central energy of the iron emission line was determined as 6.52 +0.08 −0.14 keV (90 % confidence), which is significantly lower than what is expected from a plasma in thermal equilibrium. The downward shift of the iron line center energy suggests non-equilibrium ionization states of the plasma, or presence of the non-thermal process to produce 6.4 keV fluorescent lines.

show abstract

Section: Nir Identification and Source Classificationmentioning

confidence: 97%

Section: X-ray Observation and Data Reductionmentioning

confidence: 99%

Section: X-ray Point Source Extractionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

ChandraDeep X‐Ray Observation of a Typical Galactic Plane Region and Near‐Infrared Identification

Ebisawa

Tsujimoto

Paizis

et al. 2005

ApJ

Self Cite

104

159

View full text Add to dashboard Cite

show abstract

“…In the case of the Galactic Centre, the origin of the Fe K lines is controversial (e.g. Ebisawa et al 2003;Predehl et al 2003). The 6.4 keV emission is thought to arise through fluorescence in cold Fe, which is either illuminated by X-rays emitted during a past, comparatively more active period of Sgr A * (e.g.…”

Section: Comparison To the Galactic Centrementioning

confidence: 99%

Highly ionized Fe Kαemission lines from the LINER galaxy M 81

Page

Soria

Zane

et al. 2004

A&A

View full text Add to dashboard Cite

Abstract. We present spectral and timing results from a long (130 ks) XMM-Newton EPIC observation of the nucleus of the Seyfert/LINER galaxy M 81. During the observation the X-ray flux varied by 20%, but there was no significant change in spectral shape. The 2−10 keV spectrum is well described by a power law continuum and three narrow Fe Kα emission lines at 6.4, 6.7 and 6.96 keV. The three emission lines have equivalent widths of 39 +13 −12 , 47 +13 −13 and 37 +15−15 eV respectively. The ratios of the three lines are thus more similar to those observed from the Galactic Centre region than to those typically observed from Seyfert galaxies. The high ionization lines most likely originate either from photoionized gas within 0.1 pc of the nucleus of M 81, or from a non-thermal distribution of cosmic-ray electrons interacting with the 0.2−0.6 keV thermal plasma which is found in the bulge of M 81.

show abstract

ChandraMultiwavelength Plane (ChaMPlane) Survey: An Introduction

Grindlay

Hong

Zhao

et al. 2005

ApJ

View full text Add to dashboard Cite

We introduce the Chandra Multiwavelength Plane (ChaMPlane) Survey, designed to measure or constrain the populations of low-luminosity (L x > ∼ 10 31 erg s −1) accreting white dwarfs, neutron stars and stellar mass black holes in the Galactic Plane and Bulge. ChaMPlane incorporates two surveys, X-ray (Chandra) and optical (NOAO 4m-Mosaic imaging), and a followup spectroscopy and IR identification program. The survey has now extended through the first 6 years of Chandra data using serendipitous sources detected in 105 distinct ACIS-I and-S fields observed in 154 pointings and covered by 65 deep Mosaic images in V, R, I, and Hα. ChaMPlane incorporates fields with galactic latitude |b| < ∼ 12 • and selected to be devoid of bright point or diffuse sources, with exposure time > ∼ 20ksec, and (where possible) minimum N H. We describe the scientific goals and introduce the X-ray and optical/IR processing and databases. We derive preliminary constraints on the space density or luminosity function of cataclysmic variables from the X-ray/optical data for 14 fields in the Galactic Anticenter. The lack of ChaMPlane CVs in these Anticenter fields suggests their space density is ∼3× below the value (3 × 10 −5 pc −3) found for the solar neighborhood by previous X-ray surveys. Companion papers describe the X-ray and optical processing in detail, optical spectroscopy of ChaMPlane sources in selected Anticenter fields and IR imaging results for the Galactic Center field. An Appendix introduces the ChaMPlane Virtual Observatory (VO) for online access to the X-ray and optical images and source catalogs for ready display and further analysis.

show abstract

Galactic X‐ray surveys

Cited by 3 publications

References 36 publications

ChandraDeep X‐Ray Observation of a Typical Galactic Plane Region and Near‐Infrared Identification

ChandraDeep X‐Ray Observation of a Typical Galactic Plane Region and Near‐Infrared Identification

Highly ionized Fe Kαemission lines from the LINER galaxy M 81

ChandraMultiwavelength Plane (ChaMPlane) Survey: An Introduction

Contact Info

Product

Resources

About