Accepted Cycle 16 Observing Proposals

CLUSTERS OF GALAXIES

Proposal Number	Subject Category	PI Name	Type	Time (ks)	Title
16800086	CLUSTERS OF GALAXIES	Allen	GO	145	Perseus: A New, Low-Redshift Anchor for Cluster Cosmology
16800273	CLUSTERS OF GALAXIES	O'Sullivan	GO	155	Building the intra-group medium from shock heated HI in the NGC 5903 galaxy group
16800287	CLUSTERS OF GALAXIES	Rozo	GO	120	Chandra Calibration of the Richness-Mass Relation of Galaxy Clusters: Enabling Cluster Cosmology with the DES
16800330	CLUSTERS OF GALAXIES	Wong	GO	16	Search for the outer boundary of the starburst galaxy: M82
16800337	CLUSTERS OF GALAXIES	Bonafede	GO	200	Low mach number shocks reaccelerating particles in the Intra-cluster Medium: the unique case of PLCKG287.0 +32.9
16800338	CLUSTERS OF GALAXIES	Simionescu	GO	20	An X-ray view of peculiar radio tails lacking optical counterparts in Abell 585
16800359	CLUSTERS OF GALAXIES	Eckert	GO	200	Ram-pressure stripping and ICM physics in an infalling galaxy group
16800365	CLUSTERS OF GALAXIES	Ogrean	GO	197	A Cosmic Ray Mystery: No Shock Across a Radio Relic in ZwCl 2341.1+0000
16800377	CLUSTERS OF GALAXIES	Russell	GO	200	The origin of the massive cold gas flows in the galaxy cluster A1664
16800411	CLUSTERS OF GALAXIES	Sarazin	GO	210	The Burst Cluster: Dark Matter in a Merging Cluster Host of the Short Gamma-Ray Burst GRB050509B
16800415	CLUSTERS OF GALAXIES	Donahue	GO	87	UNMASKING GALAXY CLUSTERS MASQUERADING AS QUASARS
16800445	CLUSTERS OF GALAXIES	Boehringer	GO	220	Completing the survey of the most massive southern galaxy clusters
16800453	CLUSTERS OF GALAXIES	Kato	GO	40	High-Resolution Imaging of Newborn Shock Fronts in Nearby Early-Phase Merging Cluster CIZA J1358.9-4750
16800455	CLUSTERS OF GALAXIES	van Weeren	GO	165	Abell 3411: Confronting the Relic Shock Acceleration Mystery
16800461	CLUSTERS OF GALAXIES	McNamara	GO	70	X-ray Imaging of a Gas Rich BCG in the RXJ0821.0+0752 Cluster
16800528	CLUSTERS OF GALAXIES	David	LP	340	The Highly Perturbed X-ray Bright Group NGC 5044
16800593	CLUSTERS OF GALAXIES	Giacintucci	GO	110	The unexpected SZ structure of the extreme cool core in the galaxy cluster RXCJ1504
16800596	CLUSTERS OF GALAXIES	Vrtilek	GO	160	NGC 741: Mergers and AGN feedback at the group scale
16800622	CLUSTERS OF GALAXIES	Forman	LP	370	Probing the Physics of the ICM in the Dynamically Young Cluster A1367
16800637	CLUSTERS OF GALAXIES	Markevitch	GO	200	THERMAL AND (OR?) RELATIVISTIC MATTER IN THE BRIGHTEST CLUSTER RADIO RELIC
16800665	CLUSTERS OF GALAXIES	van Weeren	GO	26	Exciting Shock Physics in Faint Galaxy Cluster Outskirts
16800690	CLUSTERS OF GALAXIES	McDonald	LP	588	A MASS-LIMITED SURVEY OF GALAXY CLUSTERS AT 1.2 < z < 1.7: PROBING THE PHYSICS OF THE ICM DURING ITS ASSEMBLY
16800711	CLUSTERS OF GALAXIES	de Gasperin	GO	27	A first look at the most powerful radio relic cluster
16800758	CLUSTERS OF GALAXIES	McDonald	GO	153	DISTANT GALAXY CLUSTERS HOSTING EXTREME CENTRAL GALAXIES
16800783	CLUSTERS OF GALAXIES	Baum	GO	130	First Chandra Observation of a remarkable 'String of Pearls' between two Merging Elliptical Galaxies
16800794	CLUSTERS OF GALAXIES	Su	GO	10	Investigating a Potential Benchmark of Relaxed Clusters out to the Virial Radius
16800805	CLUSTERS OF GALAXIES	Sarazin	GO	94	PKS B1400-33 and Abell S753: A Very Bright Radio Relic in a Poor Cluster
16800829	CLUSTERS OF GALAXIES	Vikhlinin	XVP	2100	Chandra mapping of the cosmic web converging on the virialization region of Abell 1795
16800848	CLUSTERS OF GALAXIES	Hlavacek-Larrondo	GO	70	Chandra observations of the massive galaxy cluster MACS J1447.4+0827 at z=0.3755

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800086

Title: Perseus: A New, Low-Redshift Anchor for Cluster Cosmology

Type: GO Total Time (ks): 145

PI Name: Steven Allen

Abstract: The Perseus Cluster (z=0.0179) is the nearest, massive, highly dynamically relaxed galaxy cluster. We propose short (5ks/exposure) Grid Survey observations of the cluster to provide complete Chandra coverage out to 1.2r2500, and good coverage out to r500. The observations will permit a precise measurement of the X-ray gas mass fraction in the cluster, setting down a new, low-redshift anchor for dark energy studies with such measurements. By setting this anchor at the lowest redshift possible, the observations will provide easily the most cost-effective approach to boosting the constraining power of current data, and increasing the impact of future measurements at higher redshifts. The data will also provide a powerful legacy resource for general cluster science.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+03:19:48.00	+41:30:44.00	Perseus cluster	ACIS-I	None	125.0
+03:19:48.00	+41:30:44.00	Perseus cluster	ACIS-I	None	20.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800273

Title: Building the intra-group medium from shock heated HI in the NGC 5903 galaxy group

Type: GO Total Time (ks): 155

PI Name: Ewan O'Sullivan

Abstract: Observations of the famous shock in Stephan's Quintet suggest that low-mass galaxy groups may form a significant part of their IGM via shock heating of tidally stripped HI. Stephan's Quintet is, to date, unique, but we may have found a second nearby example. The NGC 5903 group hosts a 65kpc diameter diffuse ultra-steep spectrum radio source suggestive of shock emission, and a short XMM observation shows a strong correlation between a 100kpc HI filament and bright ridges of X-ray emission, indicating that the HI has been partially shock heated by a collision with the nearby elliptical NGC 5898. XMM lacks the spatial resolution to examine these complex structures, and we request a 155ks ACIS-S pointing to investigate what may be a key example of early IGM formation in a galaxy group.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+15:18:30.10	-24:05:29.50	NGC 5903	ACIS-S	None	155.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800287

Title: Chandra Calibration of the Richness-Mass Relation of Galaxy Clusters: Enabling Cluster Cosmology with the DES

Type: GO Total Time (ks): 120

PI Name: Eduardo Rozo

Abstract: The abundance of galaxy clusters in the Dark Energy Survey (DES) will provide the definitive measurement of the growth of large scale structure of the next $\sim 5-10$ years. Realizing this promise, however, requires a calibration of the scatter in mass at fixed richness with uncertainties no larger than 5%. This level of precision can only be achieved with high resolution X-ray data. We propose 249 ksec of Chandra follow-up of 15 optically selected clusters to enable a 4% calibration of the above scatter. Our results will improve the dark energy Figure of Merit of the DES clusters by a factor of 2 relative to self-calibration analyses.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+11:36:13.00	+40:02:35.80	RM J113613.0+400235.8	ACIS-I	None	14.0
+12:49:30.90	+49:49:02.30	RM J124930.9+494902.3	ACIS-I	None	14.0
+12:34:16.10	+15:15:08.40	RM J123416.1+151508.4	ACIS-I	None	8.2
+16:03:19.00	+03:16:44.60	RM J160319.0+031644.6	ACIS-I	None	14.6
+23:07:07.50	+16:32:46.10	RM J230707.5+163246.1	ACIS-I	None	5.8
+10:47:29.00	+15:14:02.10	RM J104729.0+151402.1	ACIS-I	None	12.6
+13:34:08.70	+20:14:53.00	RM J133408.7+201453.0	ACIS-I	None	7.0
+10:54:17.50	+14:39:04.20	RM J105417.5+143904.2	ACIS-I	None	10.8
+10:17:34.30	+59:33:39.80	RM J101734.3+593339.8	ACIS-I	None	7.6
+21:18:49.10	+00:33:37.20	RM J211849.1+003337.2	ACIS-I	None	13.4
+16:43:25.40	+13:22:35.90	RM J164325.4+132235.9	ACIS-I	None	12.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800330

Title: Search for the outer boundary of the starburst galaxy: M82

Type: GO Total Time (ks): 16

PI Name: Ka-Wah Wong

Abstract: We propose to carry out joint Chandra and Suzaku observations of the starburst galaxy M82. We will search for extended clumps similar to the Northern Cap out to 45 kpc. We will also constrain the density and temperature profiles of the tenuous wind emission out to large radii. These data can place important constraints on theoretical models of starburst galaxies and their environments. We will test models such as the Chevalier & Clegg adiabatic wind model, hydrostatic halo model, shocked clouds in a wind, etc. The excellent Chandra spatial resolution combining with the low Suzaku background allows this measurement.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+09:54:42.90	+70:03:13.20	M82 N1	ACIS-I	None	16.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800337

Title: Low mach number shocks reaccelerating particles in the Intra-cluster Medium: the unique case of PLCKG287.0 +32.9

Type: GO Total Time (ks): 200

PI Name: Annalisa Bonafede

Abstract: Radio relics are arc-shaped radio sources located at the periphery of galaxy clusters. Their extension, of the order of 1 Mpc, indicates that the emitting relativistic electrons need to be (re)accelerated locally.Recently, we have found a radio relic whose emission fades gradually into the bent lobes of a radio galaxy. This spectacular emission is the first ever detected case in which the radio relic may be fed by the dead radio plasma coming from radio galaxies, and reenergised by some powerful event, like shocks. To verify this hypothesis, we need to detect the shock wave from the X-ray emission of the gas. We are therefore proposing for a 200 ksec Chandra ACIS-I observation, in order to unambiguously probe the mechanism that leads to the relic emission.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+11:50:49.20	-28:04:37.00	PLCKG287+.0 +32.9	ACIS-I	None	200.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800338

Title: An X-ray view of peculiar radio tails lacking optical counterparts in Abell 585

Type: GO Total Time (ks): 20

PI Name: Aurora Simionescu

Abstract: We propose a relatively short 20ks observation of the galaxy cluster Abell 585 at z=0.12, which currently lacks any XMM-Newton or Chandra coverage. Our recent analysis of archival VLA data of this cluster has revealed a peculiar type of diffuse radio emission, whose spectral and polarization properties are inconsistent with typical radio mini-haloes or relics; while these radio features closely resemble typical lobes of cluster radio galaxies, we have been unable to identify their host galaxies in available optical (SDSS) and infrared (WISE) surveys. In addition to our radio and optical follow-up of these intriguing features, we therefore propose to obtain complementary X-ray images which will further help us elucidate their nature.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+07:30:48.00	+40:51:10.00	Abell 585	ACIS-S	None	20.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800359

Title: Ram-pressure stripping and ICM physics in an infalling galaxy group

Type: GO Total Time (ks): 200

PI Name: Dominique Eckert

Abstract: Ram-pressure stripped tails have been observed in a handful of individual interacting galaxies and are direct signatures of structure formation processes. We discovered a spectacular tail (>600 kpc long) of hot gas trailing behind an accreting group. This tail is the first in a galaxy group and it is longer than any known similar feature by a factor of 5. Because of its long survival (>700 Myr) and irregular morphology, this structure also provides us with a unique laboratory for the study of ICM physics. We propose a 200 ks observation of this accreting substructure with Chandra with the following aims: 1) characterize precisely its morphology; 2) determine the infall velocity and study the stripping processes; 3) provide constraints on transport processes and turbulence in the local ICM.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+15:59:02.60	+27:26:15.00	A2142 NE	ACIS-S	None	200.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800365

Title: A Cosmic Ray Mystery: No Shock Across a Radio Relic in ZwCl 2341.1+0000

Type: GO Total Time (ks): 197

PI Name: Georgiana Ogrean

Abstract: Galaxy cluster mergers trigger shocks in the ICM, which can accelerate particles to relativistic energies to form radio relics. Despite recent challenges, the standard diffusive shock acceleration model remains the most commonly used to explain the shock-relic connection. We have shown that the double-relic cluster ZwCl 2341 poses the greatest challenge to our current understanding of particle acceleration at merger shocks. We propose joint Chandra+JVLA observations of ZwCl 2341 to study the connection between the shocks and the relics. The proposed observations could deliver unprecedented proof that our understanding of the origin of radio relics is incomplete, and that non-linear effects are required to explain particle acceleration at weak shocks.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+23:43:36.80	+00:19:29.60	ZwCl 2341.1+0000	ACIS-I	None	197.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800377

Title: The origin of the massive cold gas flows in the galaxy cluster A1664

Type: GO Total Time (ks): 200

PI Name: Helen Russell

Abstract: Powerful AGN outbursts pump a substantial amount of energy into their host galaxy clusters which keeps their atmospheres hot and suppresses gas cooling and star formation. Cold gas accretion onto the SMBH and AGN-driven molecular gas outflows, directly regulating the cold gas reaching the galaxy centre, are likely to be crucial elements of this feedback loop. Our ALMA observations of the brightest cluster galaxy in A1664 have revealed a circumnuclear molecular gas disk and a massive gas flow extending 10 kpc from the nucleus. Here we request a 200 ks Chandra observation of A1664 to map the X-ray properties on the same scale as the molecular gas structures, trace the rapidly cooling X-ray gas potentially feeding the disk and determine if the high velocity flow is driven by the AGN.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+13:03:42.60	-24:14:42.20	Abell 1664	ACIS-S	None	200.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800411

Title: The Burst Cluster: Dark Matter in a Merging Cluster Host of the Short Gamma-Ray Burst GRB050509B

Type: GO Total Time (ks): 210

PI Name: Craig Sarazin

Abstract: We propose a 210 ks Chandra observation of ZwCl1234.0+02916 (z=0.2214), a merging galaxy cluster where one of the BCGs hosted the short GRB050509B. Our previous Chandra TOO shows a bimodal structure, with a possible cold front at the western edge, indicating that the two subclusters are moving away from one another after first core passage. Our weak lensing analysis shows that the dark matter is also bimodal, and is centered on the two galaxy distributions, while the X-ray gas lags behind (like the Bullet Cluster). Chandra data will confirm the bimodal structure and allow the measurement of the merger velocity and the study of the segregation of dark and baryonic matter. This is likely to be a high velocity collision which will constrain the self-interaction cross-section of dark matter.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+12:36:17.80	+28:59:15.00	ZwCl 1234.0+02916	ACIS-S	None	210.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800415

Title: UNMASKING GALAXY CLUSTERS MASQUERADING AS QUASARS

Type: GO Total Time (ks): 87

PI Name: Megan Donahue

Abstract: We propose to observe 8 galaxy clusters associated with RASS Bright Sources, to follow our successful detection of 4 new luminous clusters in Cycle 15. None of these clusters, selected from the SDSS GMBCG catalog of 55,000 clusters, were previously known to be X-ray luminous clusters. These clusters may be missed by X-ray cluster surveys, as the Phoenix Cluster was, because of their association with bright point sources. Understanding objects like these and their underrepresentation in X-ray cluster surveys is important for accurately measuring the evolution of cool cluster cores and for understanding the connection between X-ray bright AGNs in brightest cluster galaxies and the ICM. We will address these issues by separating the AGN and extended X-ray contributions in these sources.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+11:31:20.90	+33:34:47.10	J113121.4+333447	ACIS-I	None	15.0
+09:27:10.60	+53:27:31.60	RXCJ092710.8+532741	ACIS-I	None	14.0
+09:09:53.30	+31:06:03.20	RXCJ090953.9+310558	ACIS-I	None	5.0
+14:42:48.30	+12:00:40.30	RXCJ144248.5+120042	ACIS-I	None	2.0
+08:28:14.20	+41:53:51.90	RXCJ082814.5+415359	ACIS-I	None	16.0
+12:15:11.00	+07:32:04.60	RXCJ121510.9+073205	ACIS-I	None	6.0
+17:06:00.50	+36:57:28.50	RXCJ170559.9+365732	ACIS-I	None	25.0
+09:16:51.90	+52:38:28.40	RXCJ091651.8+523829	ACIS-I	None	4.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800445

Title: Completing the survey of the most massive southern galaxy clusters

Type: GO Total Time (ks): 220

PI Name: Hans Boehringer

Abstract: With the recently completed REFLEX II galaxy cluster survey we obtained a new sample of the most X-ray luminous and most massive galaxy clusters comprising a total of 45 galaxy clusters (Lx>=6e44 erg/s) at z>=0.3 in the southern sky. The majority of these prominent clusters have been detected in various surveys and have been well studied in X-rays before, except for 8 clusters in our new sample. These clusters are the most interesting objects of this kind since they are prominent gravitational lensing objects, easily detected through the Sunyaev-Zeldovich effect, and important cosmological probes. To complete this sample of massive clusters, we propose Chandra observations with a total of 220 ks exposure to well characterize their global parameters and explore their morphology.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+00:18:57.10	-40:51:37.40	RXCJ0018.9-4051	ACIS-I	None	30.0
+00:41:03.40	-44:28:33.20	RXCJ0041.0-4428	ACIS-I	None	31.0
+01:38:03.00	-21:55:22.80	RXCJ0138.0-2155	ACIS-I	None	25.0
+01:51:41.90	-29:00:37.10	RXCJ0151.6-2900	ACIS-I	None	31.0
+02:19:53.10	-30:02:07.40	RXCJ0219.8-3002	ACIS-I	None	10.0
+04:39:13.10	-46:00:54.40	RXCJ0439.2-4600	ACIS-I	None	28.0
+05:14:22.90	-22:27:13.30	RXCJ0514.3-2227	ACIS-I	None	30.0
+15:16:18.30	-27:37:48.00	RXCJ1516.3-2737	ACIS-I	None	35.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800453

Title: High-Resolution Imaging of Newborn Shock Fronts in Nearby Early-Phase Merging Cluster CIZA J1358.9-4750

Type: GO Total Time (ks): 40

PI Name: Yuichi Kato

Abstract: We propose a 40 ks Chandra observation of a newly discovered near-by (z=0.07) merging cluster, CIZA J1358.9-4750. It has two X-ray humps 14 ks apart, with prominent bridge structure. Our Suzaku spectra identified a 9.1 keV hot belt in the middle of the bridge, which is 50 % higher than the temperature in the vicinity. Existing shallow (5 ks) XMM image also shows indication of surface brightness jump, although its shape is not clear especially to the west. The hot belt is resembles the prototypical newborn shock in the early major merger. With Chandra, we will determine the shock overall shape and also investigate the forward and reverse shock structure. We will combine the shock geometry with our Suzaku and radio observations and compare with our simulation to resolve the merger geometry.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+13:58:42.80	-47:45:09.40	CIZA J1358.9-4750	ACIS-I	None	40.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800455

Title: Abell 3411: Confronting the Relic Shock Acceleration Mystery

Type: GO Total Time (ks): 165

PI Name: Reinout van Weeren

Abstract: In the merging cluster A3411 a shock is found coinciding with a radio relic. Relics are large structures tracing relativistic particles that are somehow accelerated at shocks. However, the acceleration efficiency of cluster merger shocks is thought to be very low. To solve this problem, re-acceleration of mildly relativistic particles has been invoked, but this idea has not been tested observationally. In A3411 we find two radio AGNs embedded in the relic. Together with the relic's morphology, this strongly suggests that AGN fossil electrons are re-accelerated by the shock. We thus propose Chandra+JVLA observations to directly address the following question: Do radio relics trace particles directly accelerated at shocks OR do they trace re-accelerated pre-existing fossil electrons?

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+08:41:58.50	-17:30:12.50	Abell 3411	ACIS-I	None	165.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800461

Title: X-ray Imaging of a Gas Rich BCG in the RXJ0821.0+0752 Cluster

Type: GO Total Time (ks): 70

PI Name: Brian McNamara

Abstract: We propose a 70 ks Chandra observation of the RXJ0821.0+0752 galaxy cluster and its brightest galaxy (BCG). Harboring more than $10^{10}~\rm M_\odot$ of molecular gas, the BCG is among the most gas-rich galaxies known, and is thus a candidate ALMA Cycle 2 target. The Chandra observation is intended to map the cycle of atmospheric cooling into molecular clouds that may be fueling star formation and AGN feedback.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+08:21:02.20	+07:51:49.20	RXJ0821.0+0752	ACIS-S	None	70.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800528

Title: The Highly Perturbed X-ray Bright Group NGC 5044

Type: LP Total Time (ks): 340

PI Name: Laurence David

Abstract: The NGC 5044 group is the X-ray brightest group in the sky and hosts many small X-ray cavities that were inflated by weak AGN outbursts. The cumulative effect of many weak AGN outbursts may be the dominant reheating mechanism in cooling flows. While AGN feedback probably prevents the bulk of gas from cooling in NGC 5044, the presence of molecular structures, H$\alpha$ filaments, [CII] emission and star formation indicates that at least some gas is able to condense out of the hot phase. The near by 5044 group is the best target for detecting small X-ray cavities with Chandra and investigating the cumulative effect of repeated weak AGN outbursts. The wealth of multi-frequency data also makes NGC 5044 an ideal target for studying gas over a broad range of temperatures in a cooling flow.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+13:15:24.00	-16:23:07.00	NGC 5044	ACIS-S	None	340.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800593

Title: The unexpected SZ structure of the extreme cool core in the galaxy cluster RXCJ1504

Type: GO Total Time (ks): 110

PI Name: Simona Giacintucci

Abstract: A massive, relaxed galaxy cluster RXJ1504 hosts an extremely luminous cool core. We recently obtained a Sunyaev-Zeldovich map of RXJ1504 core with CARMA at 12" and 44" resolutions to study the distribution of its gas pressure. While there is large-scale agreement, we found that the peak of the SZ signal does not coincide with the X-ray peak, but instead sits at the tip of a subtle sloshing gas filament. Theoretically, it is very difficult to generate small-scale pressure nonuniformities in a non-merging cluster; something significant must be missing from our understanding of the cool core physics. Several interesting possibilities exist. We propose to obtain a better-resolved temperature map of this SZ peak with an additional longer Chandra exposure to look for the missing pressure peak.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+15:04:07.50	-02:48:16.00	RXCJ1504.1-0248	ACIS-I	None	110.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800596

Title: NGC 741: Mergers and AGN feedback at the group scale

Type: GO Total Time (ks): 160

PI Name: Jan Vrtilek

Abstract: While AGN and mergers are thought to play important roles in group and cluster evolution, their effects in galaxy groups are poorly understood. We propose to observe the NGC 741 group, which hosts both an old central radio galaxy, and a spectacular infalling head-tail source. Strongly-bent jets, a 100kpc radio trail and intriguing narrow X-ray filaments suggest that NGC 742 is moving trans-sonically, undergoing stripping and shock heating. NGC 741 possesses both an old, faint radio lobe and an X-ray cavity, whose inflating plasma may have unusual properties. We request Chandra and XMM observations of the group with the goal of examining the roles of the central AGN and infalling galaxy in heating the intra-group medium, and determining the origin of the intriguing X-ray filaments.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+01:56:21.00	+05:37:44.20	NGC 741	ACIS-S	None	160.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800622

Title: Probing the Physics of the ICM in the Dynamically Young Cluster A1367

Type: LP Total Time (ks): 370

PI Name: William Forman

Abstract: We propose a 370 ks ACIS-I observation to measure the surface brightness fluctuations in the core of A1367, a dynamically young and low temperature cluster, to probe the ICM microphysics including fundamental processes such as thermal conduction and viscosity. The key is to extend the dynamic range of the power spectrum and measure the amplitude of fluctuations on scales comparable to (or below) 10 kpc. We also will exploit cross-power-spectra of fluctuations in different energy bands and compare relative amplitudes of perturbations in these bands at different spatial scales to reveal the nature of perturbations, discriminating between adiabatic (e.g. perturbations of the gravitational potential and sound waves) and entropy perturbations.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+11:44:44.40	+19:42:04.00	Abell 1367	ACIS-I	None	370.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800637

Title: THERMAL AND (OR?) RELATIVISTIC MATTER IN THE BRIGHTEST CLUSTER RADIO RELIC

Type: GO Total Time (ks): 200

PI Name: Maxim Markevitch

Abstract: We propose deep Chandra imaging of the iconic radio relic at the northwestern periphery of A3667 - the brightest relic in the sky. Faint diffuse X-ray emission detected there by XMM and Suzaku may come from thermal plasma or have contribution from inverse Compton (IC) scattering by the radio-emitting relativistic electrons. The radio data show a network of narrow, polarized filaments, offering a unique test to distinguish between these possibilities using high-resolution X-ray imaging. The magnetic pressure should approach thermal pressure in the relic region. If the X-ray brightness is spatially correlated with the radio filaments, it is the long-sought IC signal; if anticorrelated, it is the plasma depletion effect by the strong magnetic fields in the filaments embedded in thermal gas.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+20:10:20.50	-56:25:58.00	A3667_NWRELIC_1	ACIS-I	None	100.0
+20:10:12.10	-56:27:43.00	A3667_NWRELIC_2	ACIS-I	None	100.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800665

Title: Exciting Shock Physics in Faint Galaxy Cluster Outskirts

Type: GO Total Time (ks): 26

PI Name: Reinout van Weeren

Abstract: We are constructing the first sample of galaxy cluster merger shocks with radio relics. This sample will be used to address the unsolved and fundamental problem of particle acceleration at low-Mach number shocks. We have been awarded a Suzaku Key Project to measure the temperatures across these radio relic shocks, in the faint outskirts of clusters. Here we propose short Chandra observations to greatly reduce the systematic uncertainty due to fluctuations in the unresolved source background. This systematic uncertainty severely affects our low-resolution Suzaku observations and prevents us from obtaining accurate shock Mach numbers. Having this information is crucial to solve the mystery of efficient particle acceleration at low-Mach number shocks in dilute cosmic plasmas.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+00:12:30.00	+52:36:40.00	ZwCl 0008.8+5215 WEST	ACIS-I	None	6.5
+00:11:05.00	+52:31:25.00	ZwCl 0008.8+5215 EAST	ACIS-I	None	6.5
+22:42:30.00	+52:55:60.00	CIZA J2242.8+4301 SOUTH	ACIS-I	None	6.5
+10:52:40.00	+54:54:40.00	RXC J1053.7+5452 WEST	ACIS-I	None	6.5

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800690

Title: A MASS-LIMITED SURVEY OF GALAXY CLUSTERS AT 1.2 < z < 1.7: PROBING THE PHYSICS OF THE ICM DURING ITS ASSEMBLY

Type: LP Total Time (ks): 588

PI Name: Michael McDonald

Abstract: We propose to obtain Chandra X-ray observations of a mass-limited sample of 8 galaxy clusters at 1.2 < z < 1.7. This sample complements a recently-completed survey of the 80 most massive SPT-selected clusters at 0.4 < z < 1.2 by extending the survey to the most distant, high-significance clusters detected with the South Pole Telescope (SPT). The addition of 8 clusters at z > 1.2 would allow us to probe galaxy cluster evolution out to the earliest epochs of cluster formation, at an epoch when star formation, cluster-cluster merging, satellite accretion, and AGN activity were all significantly higher than they are today. This unique sample will provide the seeds for follow-up surveys of high-redshift clusters for years to come.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+23:41:25.70	-57:24:56.90	SPT-CLJ2341-5724	ACIS-I	None	116.0
+06:40:15.60	-51:13:13.40	SPT-CLJ0640-5113	ACIS-I	None	89.0
+06:07:35.60	-44:48:11.90	SPT-CLJ0607-4448	ACIS-I	None	116.0
+04:59:42.50	-49:47:13.90	SPT-CLJ0459-4947	ACIS-I	None	144.0
+03:13:55.40	-53:34:41.20	SPT-CLJ0313-5334	ACIS-I	None	123.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800711

Title: A first look at the most powerful radio relic cluster

Type: GO Total Time (ks): 27

PI Name: Francesco de Gasperin

Abstract: We propose a 27 ks observation of the galaxy cluster PSZ1 G108.18-11.53. This distant (z=0.332) cluster hosts a newly discovered giant double radio relic system and a radio halo. The relic system is the second largest ever found, and it contains the most powerful known relic. The proposed exploratory observation will collect 5000 cts, enough to characterize the dynamical state of the cluster, to measure its global physical properties, and to detect possible density discontinuities in the ICM. The proposed observations are essential for planning deeper X-ray follow-ups, and for modeling this unique merger event using hydrodynamical simulations.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+23:22:29.70	+48:46:30.00	PSZ1 G108.18-11.53	ACIS-I	None	27.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800758

Title: DISTANT GALAXY CLUSTERS HOSTING EXTREME CENTRAL GALAXIES

Type: GO Total Time (ks): 153

PI Name: Michael McDonald

Abstract: The recently-discovered Phoenix cluster harbors the most star-forming central cluster galaxy of any cluster in the known Universe, by nearly a factor of 10. This extreme system appears to be fulfilling early cooling flow predictions, although the lack of similar systems makes any interpretation difficult. In an attempt to find other "Phoenix-like" clusters, we have cross-correlated archival all-sky surveys (in which Phoenix was detected) and isolated 4 similarly-extreme systems which are also coincident in position and redshift with an overdensity of red galaxies. We propose here to obtain Chandra observations of these extreme, Phoenix-like systems, in order to confirm them as relaxed, rapidly-cooling galaxy clusters.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+13:56:05.40	-34:21:10.90	PKS1353-341	ACIS-I	None	31.0
+17:27:22.10	+55:10:49.00	RXJ1727.3+5510	ACIS-I	None	35.0
+23:34:12.80	+07:36:27.60	CGRaBS J2334+0736	ACIS-I	None	35.0
+22:54:44.50	+13:44:29.30	NVSS J225444+134429	ACIS-I	None	52.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800783

Title: First Chandra Observation of a remarkable 'String of Pearls' between two Merging Elliptical Galaxies

Type: GO Total Time (ks): 130

PI Name: Stefi Baum

Abstract: We propose a 130 ksec Chandra observation of two merging giant elliptical galaxies in the core of a strongly lensing galaxy cluster at z=0.335. The merger is gas rich, featuring a dramatic 30 kpc chain of "beads on a string" star formation wrapping around the nuclei of the merging host galaxies. The proposed X-ray observations will (1) determine whether or not there may be an X-ray cool core powering the star formation as cold gas condenses from the hot ambient X-ray atmosphere; (2) search for X-ray signatures (shocks and cold fronts) of a merger of two clusters, which may give rise to shock-driven star formation; (3) use the X-ray data to rule out the former two scenarios, instead providing X-ray constraints on a rare and dramatic gas-rich merger of two giant elliptical galaxies.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+15:31:10.60	+34:14:25.00	SDSS J153110.59+341425.0	ACIS-S	None	130.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800794

Title: Investigating a Potential Benchmark of Relaxed Clusters out to the Virial Radius

Type: GO Total Time (ks): 10

PI Name: Yuanyuan Su

Abstract: We recently published a Suzaku study of ESO~3060170, the X-ray brightest ``fossil group," out to its virial radius. Its entropy profile rises roughly linearly with radius to 0.8 r_vir, then declines beyond r_vir. We propose to test whether this outer decline in entropy is an artifact of background uncertainties with Chandra ACIS-I. A better-constrained background will allow us to confirm whether the entropy profile indeed flattens beyond r_vir; if so, this will imply that clumpy gas occurs not just in massive clusters, but down to the scale of galaxy groups; if not, this result will point to fossil groups as being relaxed, highly evolved systems all the way out to their virial radii.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+05:40:08.20	-41:14:11.80	ESO 3060170 Offset	ACIS-I	None	10.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800805

Title: PKS B1400-33 and Abell S753: A Very Bright Radio Relic in a Poor Cluster

Type: GO Total Time (ks): 94

PI Name: Craig Sarazin

Abstract: The cluster radio relic PKS B1400-33 in the poor cluster Abell S753 will be observed with Chandra and the JVLA to detect and image the merger shock and nonthermal emission. This is the second brightest cluster radio relic known. Remarkably, it is associated with a relatively poor, cool cluster. With Chandra, we will detect the associated merger shock, and determine its compression, temperature jump, speed, and Mach number. The JVLA observations, 20 times deeper than existing data, will give the spectral curvature, and will test alternative ideas that the relic is an old radio lobe or due to a cluster accretion shock. These observations will be a strong test of merger shock acceleration, and will give the magnetic field, nonthermal energy, and shock acceleration efficiency.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+14:04:29.80	-34:00:38.70	Abell S753	ACIS-I	None	94.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800829

Title: Chandra mapping of the cosmic web converging on the virialization region of Abell 1795

Type: XVP Total Time (ks): 2100

PI Name: Alexey Vikhlinin

Abstract: Detailed observations of the "cosmic melting pot" in the virialization zone of rich galaxy clusters are a fairly new territory for the physics of clusters and the intergalactic medium. The first step has been taken with a deep Chandra study of A133, which has provided a uniquely detailed picture of the Cosmic Web converging onto the cluster virial radius and demonstrated that Chandra can probe to fainter surface brightness levels than any other X-ray observatory now operating. Many of the results from the A133 observation are potentially game-changers for our understanding of the virialization region and its proper modeling. We now need to follow this up with a similarly deep observation of at least one more cluster.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+13:48:52.30	+26:35:36.20	Abell 1795 outskirts	ACIS-I	None	2100.0

Subject Category: CLUSTERS OF GALAXIES

Proposal Number: 16800848

Title: Chandra observations of the massive galaxy cluster MACS J1447.4+0827 at z=0.3755

Type: GO Total Time (ks): 70

PI Name: Julie Hlavacek-Larrondo

Abstract: We propose to obtain deep Chandra observations of MACS J1447.4+0827 (70ks), a luminous, dynamically relaxed, cool core cluster of galaxies harboring one of the most extreme Brightest Cluster Galaxies (BCGs) known. The BCG is ultra luminous in the infrared; has one of the most massive molecular gas detections known; as well as an extensive array of H$\alpha$ filaments. This object is exceptional, and provides a unique opportunity for studying the heating and cooling balance in clusters. We also find evidence of a giant cavity (but deeper X-ray data are needed to confirm the structure). By adding 70 ks to the data, we will increase the exposure by almost an order of magnitude. This will also allow us to derive precise X-ray mass estimates which we will compare to weak-lensing mass estimates.

R.A.	Dec.	Target Name	Det.	Grating	Exp. Time (ks)
+14:47:25.90	+08:28:23.50	MACS J1447.4+0827	ACIS-I	None	70.0

The Chandra X-Ray Center (CXC) is operated for NASA by the Smithsonian Astrophysical Observatory. 60 Garden Street, Cambridge, MA 02138 USA. Email: cxchelp@head.cfa.harvard.edu Smithsonian Institution, Copyright © 1998-2024. All rights reserved.