FABIO GASTALDELLO

INAF-IASF MILAN & UC IRVINE

THE BULLET GROUP THE BULLET GROUP

1

FABIO GASTALDELLO

INAF-IASF MILAN & UC IRVINE

M. LIMOUSIN, G. FOEX, R. MUNOZ, T. VERDUGO, V. MOTTA, A. MORE, R. CABANAC, D. BUOTE, D. ECKERT, S. ETTORI, A. FRITZ, S. GHIZZARDI, P. HUMPHREY, M. MENEGHETTI,

M. ROSSETTI

THE BULLET GROUP THE BULLET GROUP

2

Galaxies Galaxies

Intra-cluster medium (ICM)Intra-cluster medium (ICM)

Thermal plasmaThermal plasma

Dark MatterDark Matter

Gravitational potentialGravitational potential

1E 0657-156 THE BULLET CLUSTER1E 0657-156 THE BULLET CLUSTER

MARKEVITCH+044

CONSTRAINTS ON DM SELF-CONSTRAINTS ON DM SELF-INTERACTION CROSS SECTIONINTERACTION CROSS SECTION

CLOWE+061

m

1

m

3-5 cm2 g-1

5

OTHER BULLET CLUSTERSOTHER BULLET CLUSTERS

W. DAWSON’S WEBSITE www.mergingclustercollaboration.org 6

IMAGE SEPARATION IMAGE SEPARATION DISTRIBUTION OF SLDISTRIBUTION OF SL

OGURI 2006

GALAXY GROUPS – POOR CLUSTERS WITH

IMAGE SEPARATION IN THE RANGE 6”-16”

HAVE BEEN SCARCELY REPORTED

7

SL2S GROUPSSL2S GROUPS

• INITIAL SAMPLE OF 13 OBJECTS (LIMOUSIN+09), A SUBSAMPLE OF THE SL2S BASED ON MULTI-COLOUR CFHTLS, IDEAL TO DETECT SL FEATURES AND FOLLOW-UP HUBBLE IMAGING (z = 0.3-0.8)

• LUMINOSITY MAPS BASED ON LIGHT DISTRIBUTION OF ELLIPTICALS HAVE FOR SOME OBJECTS COMPLICATED SHAPE. WEAK LENSING SIGNAL DETECTED FOR MANY GROUPS

8

SL2S GROUPSSL2S GROUPS

9

IMAGE SEPARATION IMAGE SEPARATION DISTRIBUTION OF SL2SDISTRIBUTION OF SL2S

MORE+1210

X-RAY FOLLOW-UPX-RAY FOLLOW-UP

• CLEARLY DIFFICULT BECAUSE WE ARE TARGETING LOW FLUX OBJECTS, HOWEVER MORE MASSIVE OBJECTS THAN PREVIOUS STUDIES (E.G., LARGEST IMAGE SEPARATION IN FASSNACHT+08 IS CLASS B2108+213 WITH RE = 2.5“)

• XMM SNAPSHOTS OF 5-10 ks TO SECURE FLUXES FOR DEEPER CHANDRA OBSERVATION. ENOUGH PHOTONS FOR MORPHOLOGY AND POSSIBLY TEMPERATURE

11

SL2SJ08544-0053

z = 0.351

BIMODAL LUMINOSITY DISTRIBUTION (BCGs at

the same redshift, MUNOZ+13).

PERTURBED LENSING CONFIGURATION WHICH

REQUIRES EXTERNAL MASS (LIMOUSIN+10)

SL2SJ08544-0053SL2SJ08544-0053

LIMOUSIN+1012

SL2SJ08544-0053SL2SJ08544-0053

ELONGATED X-RAY EMISSION TEMPERATURE OF KT=3.5±0.5 keV13

THE BULLET GROUPTHE BULLET GROUP

SEPARATION BETWEEN THE X-RAY PEAK AND THE MASS PEAK OF 25”±4” (124±20 Kpc). DM σ < 10 cm2 g-1 . LOWEST MASS TO DATE (2 X 1014 Msun ) FOR DM/BARYON SEPARATION 14

SHAN+10

SL2S J08544

SL2S J08544

15

FERNANDEZ-TRINCADO+14

THE NUMBER DENSITY OF BULLET GROUPS IS 3 TIMES LARGER THAN BULLET CLUSTERS

16

BULLET GROUP CANDIDATESBULLET GROUP CANDIDATES

SA58

SA54SA10

SA117

SA41

SA113

17

BULLET GROUP CANDIDATESBULLET GROUP CANDIDATES

XMM DATA SHOW ANOTHER INTERESTING, DISTURBED MORPHOLOGY FOR SA54

18

BULLETICITYBULLETICITY

19

MASSEY+11

Measurement of a statistical signal using lensing (Euclid) and X-ray surveys (EROSITA)

SUMMARYSUMMARY

• X-RAY FOLLOW-UP OF STRONG LENSING GROUPS HAS REVEALED ONE EXAMPLE OF BULLET GROUP, THE LOWEST MASS OBJECT TO DATE SHOWING DM-BARYONS SEPARATION.

• THERE ARE OTHER CANDIDATES SUITABLE FOR XMM OBSERVATIONS IN THE SL2S SAMPLE.

• POSSIBILITY OF A STATISTICAL STUDY OF DM-BARYONS SEPARATION (“BULLETICITY”) WITH FUTURE X-RAY AND LENSING SURVEYS.

20

THANKS !THANKS !

21

SL2S GROUPSSL2S GROUPS

22

SL2SJ08544-0053SL2SJ08544-0053

CLEARLY EXTENDED SOURCE (rc = 128 ± 56 kpc, 26” ± 11”, ß = 0.52 ± 0.07)

23

SL2SJ08544-0053SL2SJ08544-0053

24

SL2SJ08544-0053SL2SJ08544-0053

25

BULLETTICITYBULLETTICITY

MASSEY+11

26

CONSTRAINTS ON DM SELF-CONSTRAINTS ON DM SELF-INTERACTION CROSS SECTIONINTERACTION CROSS SECTION

RANDALL+08 27

BABY BULLET (MACS J0025)BABY BULLET (MACS J0025)

BRADAČ+08 28

FERNANDEZ-TRINCADO+1429