2014A&A...572L...8P


C.D.S. - SIMBAD4 rel 1.7 - 2019.10.19CEST18:03:46

2014A&A...572L...8P - Astronomy and Astrophysics, volume 572, L8-8 (2014/12-1)

Discovery of OVII line emitting gas in elliptical galaxies.

PINTO C., FABIAN A.C., WERNER N., KOSEC P., AHORANTA J., DE PLAA J., KAASTRA J.S., SANDERS J.S., ZHANG Y.-Y. and FINOGUENOV A.

Abstract (from CDS):

In the cores of ellipticals, clusters, and groups of galaxies, the gas has a cooling time shorter than 1Gyr. It is possible to probe cooling flows through the detection of FeXVII and OVII emission lines, but so far OVII has not been detected in any individual object. The Reflection Grating Spectrometers (RGS) aboard XMM-Newton are currently the only instruments able to detect OVII in extended objects such as elliptical galaxies and galaxy clusters. We searched for evidence of OVII through all the archival RGS observations of galaxy clusters, groups of galaxies, and elliptical galaxies focusing on those with core temperatures below 1keV. We have discovered OVII resonance (21.6Å) and forbidden (22.1Å) lines for the first time in the spectra of individual objects. OVII was detected at a level higher than three sigma in six elliptical galaxies: M84, M86, M89, NGC1316, NGC4636, and NGC5846. M84, M86, and M89 are members of the Virgo Cluster, the others are central dominant galaxies of groups, and most them show evidence of OVI in UV spectra. We detect no significant trend between the FeXVII and OVII resonance-to-forbidden line ratios, possibly because of the limited statistics. The observed line ratios <Fer/f,Or/f≥(0.52±0.02,0.9±0.2) indicate that the spectra of all these ellipticals are affected by resonance scattering, suggesting low turbulence. Deeper exposures will help to understand whether the FeXVII and OVII lines are both produced by the same cooling gas or by multiphase gas. Our OVII luminosities correspond to 0.2-2M/yr, which agree with the predictions for ellipticals. Such weak cooling rates would not be detected in clusters because their spectra are dominated by the emission of hotter gas, and owing to their greater distance, the expected OVII line flux would be undetectable.

Abstract Copyright:

Journal keyword(s): galaxies: clusters: intracluster medium - X-rays: galaxies - X-rays: galaxies: clusters - galaxies: ISM - galaxies: abundances - galaxies: evolution

Simbad objects: 10

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Number of rows : 10

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2019
#notes
1 NGC 1316 GiP 03 22 41.789 -37 12 29.52 9.81 9.15 8.53 7.66   ~ 1161 1
2 NGC 1332 GiP 03 26 17.321 -21 20 07.33   11.45   9.84   ~ 295 0
3 NGC 1404 GiP 03 38 51.917 -35 35 39.81 11.53 10.69 10.00 9.03   ~ 647 1
4 M 84 Sy2 12 25 03.74333 +12 53 13.1393 12.67 12.09 10.49     ~ 1609 2
5 M 86 GiG 12 26 11.814 +12 56 45.49 10.32 9.83 8.90   7.50 ~ 994 1
6 NAME Vir I ClG 12 26 32.1 +12 43 24   10.00 8.49     ~ 5645 0
7 M 89 LIN 12 35 39.8 +12 33 23 11.29 10.73 9.75     ~ 906 2
8 NGC 4636 LIN 12 42 49.867 +02 41 16.01   12.62 11.84     ~ 1025 1
9 NGC 5846 BiC 15 06 29.253 +01 36 20.29   11.9   9.74   ~ 755 1
10 IC 1459 GiP 22 57 10.60677155 -36 27 43.9953697   10.96 11.85 9.34 10.3 ~ 555 2

    Equat.    Gal    SGal    Ecl

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2019.10.19-18:03:46

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