Abstract
Using the Chandra ACIS-I instruments, we have carried out a deep X-ray observation on the Galactic plane region at (l, b) ≈ (28.°5, 0.°0), where no discrete X-ray sources have been known previously. We have detected, as well as strong diffuse emission, 274 new point X-ray sources (4 σ confidence) within two partially overlapping fields (∼250 arcmin2 in total) down to the flux limit ∼ 3 × 10-15 erg s -1 cm-2 (2 - 10 keV) and ∼ 7 × 7 × 10 -16 erg s-1 cm-2 (0.5 - 2 keV). We clearly resolved point sources and the Galactic diffuse emission, and found that ∼ 90 % of the flux observed in our field of view originates from diffuse emission. Many point sources are detected either in the soft X-ray band (below 2 keV) or in the hard band (above 2 keV), and only a small number of sources are detected in both energy bands. On the other hand, most soft X-ray sources are considered to be nearby X-ray active stars. We have carried out a follow-up near-infrared (NIR) observation using SOFI at ESO/NTT. Most of the soft X-ray sources were identified, whereas only a small number of hard X-ray sources had counterparts in NIR. Using both X-ray and NIR information, we can efficiently classify the point X-ray sources detected in the Galactic plane. We conclude that most of the hard X-ray sources are background Active Galactic Nuclei seen through the Milky Way, whereas majority of the soft X-ray sources are nearby X-ray active stars.
| Original language | English |
|---|---|
| Pages (from-to) | 687-690 |
| Number of pages | 4 |
| Journal | Unknown Journal |
| Issue number | 552 |
| Publication status | Published - 2004 |
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Keywords
- Chandra
- Diffuse emission
- ESO/NTT
- Milky way
- Near-infrared
- Survey
ASJC Scopus subject areas
- Aerospace Engineering
Cite this
A Chandra deep X-ray exposure on the Galactic plane and near infrared identification. / Ebisawa, K.; Paizis, A.; Couvoisier, T. J L; Dubath, P.; Tsujimoto, M.; Hamaguchi, K.; Beckmann, V.; Bamba, A.; Senda, A.; Ueno, M.; Kaneda, H.; Maeda, Y.; Sato, G.; Yamauchi, S.; Cutri, R.; Nishihara, E.
In: Unknown Journal, No. 552, 2004, p. 687-690.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - A Chandra deep X-ray exposure on the Galactic plane and near infrared identification
AU - Ebisawa, K.
AU - Paizis, A.
AU - Couvoisier, T. J L
AU - Dubath, P.
AU - Tsujimoto, M.
AU - Hamaguchi, K.
AU - Beckmann, V.
AU - Bamba, A.
AU - Senda, A.
AU - Ueno, M.
AU - Kaneda, H.
AU - Maeda, Y.
AU - Sato, G.
AU - Yamauchi, S.
AU - Cutri, R.
AU - Nishihara, E.
PY - 2004
Y1 - 2004
N2 - Using the Chandra ACIS-I instruments, we have carried out a deep X-ray observation on the Galactic plane region at (l, b) ≈ (28.°5, 0.°0), where no discrete X-ray sources have been known previously. We have detected, as well as strong diffuse emission, 274 new point X-ray sources (4 σ confidence) within two partially overlapping fields (∼250 arcmin2 in total) down to the flux limit ∼ 3 × 10-15 erg s -1 cm-2 (2 - 10 keV) and ∼ 7 × 7 × 10 -16 erg s-1 cm-2 (0.5 - 2 keV). We clearly resolved point sources and the Galactic diffuse emission, and found that ∼ 90 % of the flux observed in our field of view originates from diffuse emission. Many point sources are detected either in the soft X-ray band (below 2 keV) or in the hard band (above 2 keV), and only a small number of sources are detected in both energy bands. On the other hand, most soft X-ray sources are considered to be nearby X-ray active stars. We have carried out a follow-up near-infrared (NIR) observation using SOFI at ESO/NTT. Most of the soft X-ray sources were identified, whereas only a small number of hard X-ray sources had counterparts in NIR. Using both X-ray and NIR information, we can efficiently classify the point X-ray sources detected in the Galactic plane. We conclude that most of the hard X-ray sources are background Active Galactic Nuclei seen through the Milky Way, whereas majority of the soft X-ray sources are nearby X-ray active stars.
AB - Using the Chandra ACIS-I instruments, we have carried out a deep X-ray observation on the Galactic plane region at (l, b) ≈ (28.°5, 0.°0), where no discrete X-ray sources have been known previously. We have detected, as well as strong diffuse emission, 274 new point X-ray sources (4 σ confidence) within two partially overlapping fields (∼250 arcmin2 in total) down to the flux limit ∼ 3 × 10-15 erg s -1 cm-2 (2 - 10 keV) and ∼ 7 × 7 × 10 -16 erg s-1 cm-2 (0.5 - 2 keV). We clearly resolved point sources and the Galactic diffuse emission, and found that ∼ 90 % of the flux observed in our field of view originates from diffuse emission. Many point sources are detected either in the soft X-ray band (below 2 keV) or in the hard band (above 2 keV), and only a small number of sources are detected in both energy bands. On the other hand, most soft X-ray sources are considered to be nearby X-ray active stars. We have carried out a follow-up near-infrared (NIR) observation using SOFI at ESO/NTT. Most of the soft X-ray sources were identified, whereas only a small number of hard X-ray sources had counterparts in NIR. Using both X-ray and NIR information, we can efficiently classify the point X-ray sources detected in the Galactic plane. We conclude that most of the hard X-ray sources are background Active Galactic Nuclei seen through the Milky Way, whereas majority of the soft X-ray sources are nearby X-ray active stars.
KW - Chandra
KW - Diffuse emission
KW - ESO/NTT
KW - Milky way
KW - Near-infrared
KW - Survey
UR - http://www.scopus.com/inward/record.url?scp=23844546516&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=23844546516&partnerID=8YFLogxK
M3 - Article
SP - 687
EP - 690
JO - Nuclear Physics A
JF - Nuclear Physics A
SN - 0375-9474
IS - 552
ER -