1 / 25

Intracluster Planetary Nebulae as Dynamical Probes of the Diffuse Light in Galaxy Clusters

Magda Arnaboldi INAF, Observatory of Turin. Intracluster Planetary Nebulae as Dynamical Probes of the Diffuse Light in Galaxy Clusters. Magda Arnaboldi, PNe as Astronomical Tools July 2 nd , 2005. Observations of Diffuse L ight

ciara
Download Presentation

Intracluster Planetary Nebulae as Dynamical Probes of the Diffuse Light in Galaxy Clusters

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Magda Arnaboldi INAF, Observatory of Turin Intracluster Planetary Nebulae as Dynamical Probes of the Diffuse Light in Galaxy Clusters Magda Arnaboldi, PNe as Astronomical Tools July 2nd, 2005 • Observations of DiffuseLight • Intracluster Light in Cosmological Simulations • ICPNe in the Virgo Cluster: projected phase-space distribution • Future prospects

  2. Observations of ICL in clusters Since 1995, large CCD and mosaic cameras have allowed measurements of ICL in Abell clusters. • 1951. Zwicky claimed the discovery of diffuse light in the regions between galaxies belonging to the Coma cluster. • 1971-1977. Follow-up photographic surveys for diffuse light in Coma and rich clusters. • 1989-1995. CCD photometry of diffuse light. First accurate measurements in Coma (Berstein et al. 1995). • Problems • typical surface brightness of the ICL is less than 1% of sky brightness; • it is difficult to disentangle between diffuse light associated with the halo of the cD galaxy at the cluster centre and the diffuse light component

  3. Measurements of *in nearby clusters Presence of diffuse light is traced by existence of tails, arcs and/or plumes with typical B = 27.8 mag ”, very narrow (~ 2 kpc ) and extended (~100 kpc) in Coma and Centaurus. (Gregg & West 1998, Threntam & Mobasher 1998, Calcáneo-Roldán et al. 2000) Diffuse light measured in z∼0.25 clusters from stacking of SDSS imaging data. SB measurements of the ICL ranges from 27.5 mag ” at 100 kpc to 32 mag ” at 700 kpc in the observed R band (Zibetti et al. 2005). Diffuse light measured by deep CCD photometry out to large radii in clusters. (Abel 1651: Gonzalez et al. 2000; Abell 1413 & MKW7:Feldmeier et al. 2002, 2004a; HGC 90: White et al. 2003; Gonzalez et al. 2004).

  4. Intergalactic Supernovae(Gal-Yam et al. 2003) & Novae(Neil et al. 2004). • Intergalactic Globular Clusters(West et al. 1995, Jordàn et al. 2003) • UltraCompact Dwarfs (Drinkwater et al. 2003) • Intracluster red giant stars (IRGB)(Ferguson, Tanvir & von Hippel, 1998; Durrell et al. 2002). Excess of red number counts in Virgo IC fields with respect to the HDF. • Compact isolated HII region(Gerhard, Arnaboldi, Freeman, Okamura 2002). It will dissolve by internal process in 108 yr. Stars and metals will then be added to the diffuse stellar population nearby. • IC HI cloud (Oosterloo & Van Gorkom 2005) Direct detections of IC stars An alternative method for probing intracluster light is through the direct detection and measurements of the stars themselves IC stars and gas in Virgo cluster

  5. We expectdifferent distribution functions f(x,v) for the ICL depending on the formation mechanism. Importance of ICL in galaxy clusters The ICL in cluster is relevant for the baryonic fraction condensed in stars, star formation efficiency, and the metal enrichment of ICM via IC stars, especially in the cluster centre. It contains a fossil record of galaxy evolution and interactions in the cluster. Merritt (1984): The ICL is removed from galaxies early during the cluster collapse and its distribution is predicted to follow closely that of galaxies. ICL smoothly distributed and dynamically old Moore et al. (1996): the ICL is produced during galaxy harassment and tidal stirring during late infall.ICL still distributed in tails or plumes, dynamically young.

  6. Cosmological Simulations of Cluster Formation from Springel et al. (2001) • High-resolution resimulation of a part of a Universe that collapes into a galaxy cluster. Dark matter subhalos grow, fall into the cluster, may survive or merge into larger halos. • same processes may act on stars in galaxies, producing also ICL

  7. Transvr. Velocities Radial Velocities R,Vz x,Vz y,Vz The two-dimensional phase space diagrams in one clustershow filaments, clusters of particles, and empty regions, all of which indicate a young dynamical age! Velocity distributions and projected phase space diagrams for the IC stars N. Napolitano et al. 2003, ApJ, 594, 172

  8. Cosmological Hydrodynamic Simulations with Star Formation and Feedback • Studies of ICL in cosmological simulations require a model of star formation from cold gas, including cooling and feedback effects. Recent studies are by Murante+2004, Willman+2004, Sommer-Larsen+2005.Here we use Gadget-2 with the two-phase model of Springel & Hernquist (2003). • Current hydrodynamic simulations have significantly lower particle number than dark matter only simulations. Thus they cannot resolve small galaxies in clusters, probably causing overestimate of predicted ICL fraction. Recent high-resolution simulations obtain correct half-mass radii for galaxies above few 1010M. The large galaxies contribute a substantial part of the ICL; this part can be studied. • Galaxies must be identified by a substructure-finding algorithm; here we use SKID (Stadel 2001).

  9. ICL in a Cosmological Tree+SPH Simulation Gadget-2 (V. Springel) Star Formation Cooling (Z=0) 2x4803 particles Mass Resolution:DM: 4.6 109 h-1 MGas: 6.9 108 h-1 M Softening: 7.5 h-1 Box Size: 192 h-1 Mpc CDM Concordance model (8=0.8) • We identified 117 clusters with M>1014 h-1M • Stars in clusters were divided in two classes: bound & unbound. • we evaluated radial density profiles of the two components G. Murante et al. 2004, ApJ, 607, L83

  10. “stacked” 2D star profile used. • Fit range: from center to radius@1/3 central surface density • Sersic fit is critically sensitive to the range • =3.66 (total average), 4.37 (low-luminosity objects), 1.24 (high luminosity objects)Clear evidence for ICL at large radii! Sersic fits Galaxies ICL Sersic fit ICL more centrally concentrated than galaxy light (see also Zibetti et al. 2005)

  11. More massive clusters show greater ICL fractions • Stars in field are older than stars in galaxies (“slow” tidal effects?). ICL fractions, star ages Murante et al. 2004; see also Sommer-Larsen et al. 2005

  12. High resolution cosmological simulations Gadget-2 (V. Springel) Star Formation Cooling (Z=0) Feedback 1.5 106 particles in Cluster Mass Resolution:DM: 1.0 108 h-1 MGas: 1.5 107 h-1 M Softening: 2.1 h-1 Mass 1.6 1014 h-1 M Virial R: 1.1 h-1 Mpc CDM Concordance model (8=0.8, h=0.7) Borgani et al. (2005)

  13. Murante et al. 2005, in prep. Distribution of Dark Matter and Stars z=3 z=1 z=0

  14. Galaxies and Intracluster Stars z=3 z=1 z=0

  15. ON-[OIII] ON-H OFF-(V+R) • We obtain PN number density distribution and 2D radial velocity fields in regions where the stellar surface brightness is too faint with respect to the night sky! ICPNe in the Vigo cluster: projected phase-space distribution • PNe trace light because the luminosity-specific stellar death rate should be independent of the precise state of the underlying stellar population (Renzini & Buzzoni 1986). • The [OIII] line emission at 5007Å is the strongest emission from a PN; it allows the identification &the measurement of its radial velocity

  16. Planetary Nebulae as tracers of cluster evolution • ICPNe as light tracers: • Narrow band imaging surveys with large field mosaic cameras (WFI@ESOMPI 2.2m tel. + SuprimeCam@SUBARU) • Development+tests of selection criteria based on photometric catalogs from Sextractor(Arnaboldi et al. 2003, ESO Messenger 112, 37)for the identification of the ICPNe associated with the ICL (Arnaboldi et al. 1996,2002, 2003; Okamura et al. 2002; Feldmeier et al. 1998, 2002, 2003, 2004; Aguerri et al. 2005, AJ, 129, 2585). • ICPNe as kinematical tracers: • Follow up studies aiming at measuring spectra from multi-slitspectrograph (FORS2 @ ESO VLT; Gerhard et al. 2002, ApJ, 580, L121, Arnaboldi et al. 2003, AJ, 125, 514) • First spectra from multi-fiber spectrograph for a statistical significant sample of ICPN (FLAMES @ ESO VLT; Arnaboldi et al. 2004, ApJ, 614, L33; ESO PR 24/04)

  17. Current surveys Layout of the fields already acquired within this project in the Virgo cluster(Map of Virgo from Binggelli et al. 1987). Mosaic image in [OIII] obtained at the WFI@ESO-MPI 2.2m tel. Mosaic image in [OIII] obtained with the SuprimeCam @Subaru 8.2m tel.

  18. Results from narrow band surveys No ICPN in LPC. Agreement with Kud+2000 The distribution of ICPNe in the Subaru field is highly inhomogeneous HST RGBs. From Aguerri, Gerhard, Arnaboldi & al. 2005, AJ, 129, 2585 • The ICPNe number density distribution in the Virgo cluster is highly inhomogeneous: • inhomogeneous distribution in single fields, • field-to-field number density fluctuations.

  19. Results from narrow band surveys (cont.) Significant field-to-field variation of the ICL in the Virgo cluster No clear number density trend with distance from cluster center in M87 Mean surface luminosity density of ICL in Virgo core : 2.7 106L ’ (note the large rms = 2.1 106L ’ due to field-to-field variations!) Mean surface brightness of ICL in Virgo core :B=29 mag ” Mean fraction of light in ICL:<10 %(Aguerri et al. 2005; see also Feldmeier et al. 2004) Fraction of stars in the ICL increases with the density of the environment: <2% in loose groups (Castro-Rodriguez+2003, Durrel et al. 2004), <10% in Virgo-like (Arnaboldi et al. 2003, Feldmeier et al. 2004, Aguerri et al. 2005),  20% in rich clustersincluding cD halos(Gonzalez et al. 2000, Feldmeier et al. 2002, Zibetti et al. 2005).

  20. April 2002 FORS2 @ VLT & DOLORES @ TNG (in the Subaru field only) March 2003 FLAMES @ VLT for FCJ, Core and Subaru fields Flames FOV. Ly FORS2 & Flames of ICPNe spectra show the [OIII] doublet! ICPN single spectra M.Arnaboldi et al. 2004, ApJ, 614, L33 Results from spectroscopic follow-up….

  21. PN in the M87 halo vmean = 1280 km/s =240 km/s M87 ICPNe: they are brighter than the PNLF cut off for M87 M84 NGC 4388 M86

  22. 721 730 -150 750 1025 226 2097 1151 3049 1191 671 I34, I35, I36, I38 are over-luminous [OIII] emitters & are bound to M84 – Pop. Effects. 797 2373 Flames FOV Observed ICPN radial velocities in the Subaru field

  23. Implications on adopted criteria • We understand the selection biases that may lead to wrong identification, i.e. continuum objects erroneously classified as emission line, in on-off imaging surveys on mosaic frames. • The fraction of spectroscopically confirmed targets is now f>80 % (down to the limiting magnitudes), while in Freeman et al. (2000) was 50%! Summary spectroscopic results! • Giant galaxies in clusters are very extended - PNe still associated with M87 out to ~70 kpc & very extended halo also around M84 • The velocity histograms show strong field-to field variations. • Dynamical times at the location of these fields are from 2× 108 yr (FCJ) to 8×108 yr (SUB). Phase mixing to erase field-to-field variations would take few Gyr.

  24. Conclusions • Observations indicate that diffuse light is important in understanding cluster evolution, star formation history and the ICM enrichment. • Measuring the projected phase space constraints how and when this light originated and ICPNe are the only abundant stellar component of the ICL whose kinematics can be measured. • We can then explore the effect of low/dense environment on galaxy evolution with MSIS technique!(see O. Gerhard’s talk, this conference. )

More Related