Probes for Nearby Galaxies

Crampton, D.; Gussie, Gt; Cowley, A. P.; Schmidtke, P. C.

doi:10.1086/118653

Cited by 24 publications

(26 citation statements)

References 16 publications

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“…Behind the LMC are X-ray emitters corresponding to HS 17, HS 257 (Haberl & Pietsch 1999) and HS 356 (Crampton et al 1997). In particular, HS 356 in a rich LMC field has been catalogued not only as star cluster (Hodge & Sexton 1966;Kontizas et al 1990) but as a galaxy as well (Lauberts 1982).…”

Section: Nature Of the Objects Towards The Cloudsmentioning

confidence: 99%

Background galaxies as reddening probes throughout the Magellanic Clouds

Dutra

Bica

Clariá

et al. 2001

A&A

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Abstract.We study the spectral properties in the range 3600Å-6800Å of the nuclear region of galaxies behind the Magellanic Clouds. The radial velocities clarified the nature of the objects as background galaxies or extended objects belonging to the Clouds. For most galaxies behind the main bodies of the LMC and SMC, radial velocities were measured for the first time. In the present sample typical LMC background galaxies are nearby (4000 < V (km s −1 ) < 6000), while SMC's are considerably more distant (10 000 < V (km s −1 ) < 20 000). We determine the reddening in each line of sight by matching a reddening-free galaxy template with comparable stellar population. For the LMC main body we derive a combined Milky Way and internal reddening value E(B−V )MW+i = 0.12±0.10, while for the SMC E(B−V )MW+i = 0.05±0.05. By subtracting Milky Way reddening values for galaxies projected onto the surroundings of each Cloud, we estimate average internal reddening values ∆E(B − V )i = 0.06 and 0.04, respectively for the main bodies of the LMC and SMC. The Clouds are optically thin, at least in the directions of the studied background galaxies which are often difficult to be identified as such on ESO/SERC sky survey images. Nevertheless, more reddened zones may occur where it is difficult to identify galaxies.

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Section: Nature Of the Objects Towards The Cloudsmentioning

confidence: 99%

Background galaxies as reddening probes throughout the Magellanic Clouds

Dutra

Bica

Clariá

et al. 2001

A&A

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“…A good starting point for searching for quasars is to utilize the fact that they are often bright in X-rays, and a considerable number of quasars have been found in that way (including the ones from Crampton et al 1997). However, the limited spatial resolution of earlier X-ray missions rendered this method impractical for the dense parts of the LMC, where a single X-ray source would have many optical candidates in its error box.…”

Section: Introductionmentioning

confidence: 99%

Discovery of Four X-Ray Quasars behind the Large Magellanic Cloud

Dobrzycki

Groot

Macri

et al. 2002

The Astrophysical Journal

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We present the discovery of four X-ray quasars ( , 0.53, 0.61, and 1.63) located behind the Large z p 0.26 em Magellanic Cloud; three of them are located behind the bar of the LMC. The quasars were identified via spectroscopy of optical counterparts to X-ray sources found serendipitously by the Chandra X-Ray Observatory satellite. All four quasars have archival VI photometry from the second phase of the Optical Gravitational Lensing Experiment (OGLE-II); one of them was found by OGLE to be variable. We present the properties of the quasars and discuss their possible applications.

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“…Background galaxies: we considered the 26 background quasars seen in projection toward NGC 45 by the visible survey conducted by Crampton et al (1997): we find no associations between our detected discrete X-ray sources and those quasars. Using the NASA Extragalactic Database (NED) 15 , we searched for other known external galaxies that could be counterparts to the detected X-ray sources.…”

Section: Counterparts To Discrete X-ray Sources Detected At Other Wavmentioning

confidence: 81%

CHANDRAAND VERY LARGE ARRAY OBSERVATIONS OF THE NEARBY Sd GALAXY NGC 45

Pannuti

Swartz²,

Laine

et al. 2015

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We present an analysis of high angular resolution observations made in the X-ray and the radio with the Chandra X-ray Observatory and the Karl Jansky Very Large Array (VLA), respectively, of the nearby spiral galaxy NGC 45. This galaxy is the third that we have considered in a study of the supernova remnant (SNR) populations of nearby spiral galaxies and the present work represents the first detailed analysis of the discrete X-ray and radio source populations of this galaxy. We analyzed data sets from the three pointed observations made of this galaxy with Chandra along with a merged data set obtained from combining these data sets: the total effective exposure time of the merged data set is 63515 s. A total of 25 discrete X-ray sources are found in the entire field of view of the ACIS-S3 chip, with 16 sources found within the visual extent of the galaxy. We estimate that as many as half of the sources detected in the entire field of view of the ACIS-S3 chip and seven of the sources detected in the optical extent of NGC 45 may be background sources. We analyzed the spectral properties of the discrete X-ray sources within the galaxy and conclude that the majority of these sources are X-ray binaries. We have searched for counterparts at different wavelengths to the discrete X-ray sources and we find two associations: one with a star cluster and the other with a background galaxy. We have found one source that is clearly variable within one observation and seven that are seen to vary from one observation to another. We also conduct a photometric analysis to determine the near-infrared fluxes of the discrete X-ray sources in Spitzer Infrared Array Camera channels. We constructed a cumulative luminosity function of the discrete X-ray sources seen toward NGC 45: taking into account simultaneously the luminosity function of background sources, the fitted slope of the cumulative luminosity function Γ = -1.3 1.6 0.7 -+ (all error bounds correspond to 90% confidence intervals). The VLA observations reveal seven discrete radio sources: we find no overlaps between these sources and the X-ray detected sources. Based on their measured spectral indices and their locations with respect to the visible extent of NGC 45, we classify one source as a candidate radio SNR associated with the galaxy and the others as likely background galaxies seen in projection toward NGC 45. Finally, we discuss the properties of a background cluster of galaxies (denoted as CXOU J001354.2-231254.7) seen in projection toward NGC 45 and detected by the Chandra observations. The fit parameters to the extracted Chandra spectra of this cluster are a column density N H = 0.07 (<0.14) × 10 22 cm −2 , a temperature kT = 4.22 1.42 2.08 -+ keV, an abundance Z = 0.30(<0.75) relative to solar and a redshift z = 0.28 ± 0.14. From the fit parameters we derive an electron number density n e = 4(±1) × 10 −3 cm −3 , an unabsorbed X-ray luminosity L 0.5 7.0 keV-8.77(±0.96) × 10 43 erg s −1 for the cluster and an X-ray emitting mass M = 2.32(±1.75) × 10 12 M  .

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Probes for Nearby Galaxies

Cited by 24 publications

References 16 publications

Background galaxies as reddening probes throughout the Magellanic Clouds

Background galaxies as reddening probes throughout the Magellanic Clouds

Discovery of Four X-Ray Quasars behind the Large Magellanic Cloud

CHANDRAAND VERY LARGE ARRAY OBSERVATIONS OF THE NEARBY Sd GALAXY NGC 45

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