A Population of Compact Elliptical Galaxies Detected with the Virtual Observatory

Chilingarian, Igor; Cayatte, V.; Revaz, Yves; Додонов, С. Н.; Durand, Daniel; Durret, F.; Micol, A.; Slezak, E.

doi:10.1126/science.1175930

Cited by 116 publications

(171 citation statements)

References 35 publications

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“…This makes them analogous to ultra-compact dwarf (UCDs) galaxies (Drinkwater et al 2003) observed in the nearby Virgo and Fornax clusters, which are known to have mass-tolight ratios consistent with the Kroupa IMF when the two-body relaxation timescales are long (Chilingarian et al 2011). UCDs are proven to be tidally stripped galactic nuclei by the recent discovery of central massive black holes (Seth et al 2014) and by their stellar population properties (Francis et al 2012) similar to much more massive tidally stripped M32-like compact elliptical galaxies (Chilingarian et al 2009;Chilingarian & Zolotukhin 2015). The only known stellar systems where central luminosity densities exceed 10 5 L pc −3 are nuclear star clusters in low and intermediate luminosity galaxies, cEs, some UCDs (Evstigneeva et al 2008) and some globular clusters.…”

Section: Discussionmentioning

confidence: 99%

The Slowest Spinning X-Ray Pulsar in an Extragalactic Globular Cluster

Zolotukhin

Bachetti

Sartore

et al. 2017

ApJ

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Neutron stars are thought to be born rapidly rotating and then exhibit a phase of a rotation-powered pulsations as they slow down to 1-10 s periods. The significant population of millisecond pulsars observed in our Galaxy is explained by the recycling concept: during an epoch of accretion from a donor star in a binary system, the neutron star is spun up to millisecond periods. However, only a few pulsars are observed during this recycling process, with relatively high rotational frequencies. Here we report the detection of an X-ray pulsar with P spin = 1.20 s in the globular cluster B091D in the Andromeda galaxy, the slowest pulsar ever found in a globular cluster. This bright (up-to 30% of the Eddington luminosity) spinning-up pulsar, persistent over the 12 years of observations, must have started accreting less than 1 Myr ago and has not yet had time to accelerate to hundreds of Hz. The neutron star in this unique wide binary with an orbital period P orb = 30.5 h in a 12 Gyr old, metal rich star cluster, accretes from a low mass, slightly evolved post-main sequence companion. We argue that we are witnessing a binary formed at relatively recent epoch by getting a ∼0.8M star in a dynamical interaction -a viable scenario in a massive dense globular cluster like B091D with high global and specific stellar encounter rates. This intensively accreting non-recycled X-ray pulsar provides therefore a long-sought missing piece in the standard pulsar recycling picture.

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Section: Discussionmentioning

confidence: 99%

The Slowest Spinning X-Ray Pulsar in an Extragalactic Globular Cluster

Zolotukhin

Bachetti

Sartore

et al. 2017

ApJ

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“…Brodie et al 2011;Misgeld & Hilker 2011). This distinctively differentiates them from their low density counterparts dwarf ellipticals (dE; Chilingarian et al 2009). In fact, the vast majority of known cEs are located close to a much larger host galaxy, which plausibly has caused the threshing.…”

Section: Introductionmentioning

confidence: 99%

“…These are LEDA 3126628, LEDA 4544863, J075140.40+501102.6 (J07+50 hereafter), J160537.21+142441.2 (J16+14 hereafter), NGC 1272-cE1, NGC 2832-cE, NGC 2892 In addition, seven new objects are reported here as cEs for the first time, found through SQL searches. Automated searches for cEs in SDSS spectroscopic catalogs were first pioneered by Chilingarian et al (2009) and CZ+15, and we are developing new search techniques along similar lines (Dixon et al, in prep.). We thus use parameters previously calibrated by known cEs, imposing a redshift range (0.007< z <0.035), a stellar mass range (9.0 < logM < 13.0) and most importantly, a very restrictive size range (0.02 < R e (kpc) < 0.6).…”

Section: Samplementioning

confidence: 99%

“…Compact ellipticals (cEs) are relatively rare galaxies in the local Universe, with only about two hundred objects currently known (Chilingarian et al 2009;Norris et al 2014;Chilingarian & Zolotukhin 2015). They are non star forming galaxies typically characterized by low stellar masses of 10 8 M * /M ⊙ 10 10 , very compact effective radii of 100 R e 1000 pc and very high stellar densities.…”

Section: Introductionmentioning

confidence: 99%

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On the formation mechanisms of compact elliptical galaxies

Ferré-Mateu

Forbes

Romanowsky

et al. 2017

Monthly Notices of the Royal Astronomical Society

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In order to investigate the formation mechanisms of the rare compact elliptical galaxies (cE) we have compiled a sample of 25 cEs with good SDSS spectra, covering a range of stellar masses, sizes and environments. They have been visually classified according to the interaction with their host, representing different evolutionary stages. We have included clearly disrupted galaxies, galaxies that despite not showing signs of interaction are located close to a massive neighbour (thus are good candidates for a stripping process), and cEs with no host nearby. For the latter, tidal stripping is less likely to have happened and instead they could simply represent the very low-mass, faint end of the ellipticals. We study a set of properties (structural parameters, stellar populations, star formation histories and mass ratios) that can be used to discriminate between an intrinsic or stripped origin. We find that one diagnostic tool alone is inconclusive for the majority of objects. However, if we combine all the tools a clear picture emerges. The most plausible origin, as well as the evolutionary stage and progenitor type, can be then determined. Our results favor the stripping mechanism for those galaxies in groups and clusters that have a plausible host nearby, but favors an intrinsic origin for those rare cEs without a plausible host and that are located in looser environments.

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“…Kaur et al 2010), although those studies were hampered by high source density and high probability of random coincidence in 1 arcmin-scale X-ray error boxes of ASCA detections in the Galactic plane. In our study, we decided to adopt the innovative VO-powered research concept (Chilingarian et al 2009a) including the three steps: (1) search for candidate object(s) using VO technologies and infrastructure in a semi-automatic way; (2) follow-up observations; (3) interpretation of newly obtained data together with all the information available from the VO. We note that the VObased identification of an X-ray source presented hereafter was made during the tutorial for undergraduate students held at the Sternberg Astronomical Institute in May 2009 1 .…”

Section: Identification Of Ax J194939+2631mentioning

confidence: 99%

Virtual Observatory based identification of AX J194939+2631 as a new cataclysmic variable

Zolotukhin

Chilingarian

2010

A&A

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We report the discovery of a new cataclysmic variable (CV) among unidentified objects from the ASCA Galactic Plane Survey made using the Virtual Observatory data mining. First, we identified AX J194939+2631 with IPHAS J194938.39+263149.2, the only prominent Hα emitter among 400 sources in a 1 arcmin field of the IPHAS survey, then secured as a single faint X-ray source found in an archival Chandra dataset. Spectroscopic follow-up with the 3.5-m Calar Alto telescope confirmed its classification as a CV, possibly of magnetic nature. Our analysis suggests that AX J194939+2631 is a medium distance system (d ≈ 0.6 kpc) containing a late-K or early-M type dwarf as a secondary component and a partially disrupted accretion disc revealed by the double-peaked Hα line. However, additional deep observations are needed to confirm our tentative classification of this object as an intermediate polar.

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A Population of Compact Elliptical Galaxies Detected with the Virtual Observatory

Abstract: Science, 326, Issue 5958, pp. 1379-1382 (2009)International audienc

Cited by 116 publications

References 35 publications

The Slowest Spinning X-Ray Pulsar in an Extragalactic Globular Cluster

The Slowest Spinning X-Ray Pulsar in an Extragalactic Globular Cluster

On the formation mechanisms of compact elliptical galaxies

Virtual Observatory based identification of AX J194939+2631 as a new cataclysmic variable

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