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NASA Hubble Space Telescope Daily Report # 3668

Status Report From: Space Telescope Science Institute
Posted: Thursday, August 5, 2004

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 3668

PERIOD COVERED: DOY 217

OBSERVATIONS SCHEDULED

ACS/HRC/WFC 10004

The Physics of Relativistic Jets: Chandra Imaging of Extended Jets in Gamma-loud Blazars

Extended jets have been a key target for Chandra yet only recently has the kpc-scale jet physics been compared to that of the inner, parsec-scale jets. Such a comparison reveals the jet deceleration, power dissipation, pressure gradient, and confinement mechanism --- all essential ingredients for understanding the relativistic jets that characterize radio- loud AGN. Currently, few data exist to make this comparison. We propose to double the sample, with Chandra observations of 4 gamma-loud blazars: 0954+556 and 1229-021, the only 2 bright radio jets not yet observed by Chandra; and 0208-512 and 3C 454.3, observed in A03 with much too short exposures. We also propose HST multi-band ACS imaging of jet knots in 0208-512, 0954+556 and 3C 454.3.

ACS/HRC/WFC 10061

CCD Daily Monitor

This program consists of basic tests to monitor, the read noise, the development of hot pixels and test for any source of noise in ACS CCD detectors. This programme will be executed once a day for the entire lifetime of ACS.

ACS/HRC/WFC 10206

What drives the outflows in powerful radio galaxies?

There is increasing speculation that activity-induced outflows are an important feedback mechanism in evolution of galaxy bulges, yet uncertainties remain about the nature, dominant driving mechanism and powers of the outflows. In order to address these issues, we propose to make deep ACS and STIS observations of two compact radio sources in which we recently found unequivocal evidence for powerful emission line outflows, and in which all the potential drivers for the outflows -- quasar nuclei, relativistic jets and starbursts -- are known to be present. Using the unique capabilities of HST/ACS we will map the outflow regions in these sources at high spatial resolution and thereby determine the dominant outflow driving mechanism. In addition, by combining the morphological information from the ACS data with information on the kinematics and physical conditions derived from STIS and ground-based spectra, we will determine the mass outflow rates and powers in the outflows. This will be the first comprehensive study of the near-nuclear outflows in radio galaxies. Such studies are crucial for determining whether the activity associated with powerful extragalactic radio sources has a major impact on the evolution of the host early-type galaxies.

ACS/HRC/WFC 9728

Tracing the History of Cosmic Expansion to z~2 with Type Ia Supernovae

Type Ia supernovae {SNe Ia} provide the only direct evidence for an accelerating universe, an extraordinary result that needs the most rigorous test. The case for cosmic acceleration rests on the observation that SNe Ia at z = 0.5 are about 0.25 mag fainter than they would be in a universe without acceleration. A powerful and straightforward way to assess the reliability of the SN Ia measurement and the conceptual framework of its interpretation is to look for cosmic deceleration at z > 1. This would be a clear signature of a mixed dark-matter and dark-energy universe. Systematic errors in the SNe Ia result attributed to grey dust or cosmic evolution of the SN Ia peak luminosity would not show this change of sign. We have obtained a toehold on this putative ``epoch of deceleration'' with SN 1997ff at z = 1.7, and 3 more at z > 1 from our Cycle 11 program, all found and followed by HST. However, this is too important a test to rest on just a few objects, anyone of which could be subject to a lensed line-of-sight or misidentification. Here we propose to extend our measurement with observations of twelve SNe Ia in the range 1.0 < z < 1.5 or 6 such SNe Ia and 1 ultradistant SN Ia at z = 2, that will be discovered as a byproduct from proposed Treasury and DD programs. These objects will provide a much firmer foundation for a conclusion that touches on important questions of fundamental physics.

ACS/SBC 9814

The Nature of the UV Excess in the Jet of 3C273

We propose to obtain a 3-orbit far-ultraviolet exposure of 3C 273's jet with ACS/SBC. Combining this with our existing and HST data, we will determine the spectrum of the UV excess emission from this jet. Hence, we will establish whether the UV excess is of common origin with the jet's X-rays. This jet has long served as a test case for all extragalactic jets, as it is both long {over 20 arcsec} and bright. Our request for additional observations is motivated firstly by our VLA/HST study of the jet in 3C 273. It has provided evidence for distributed particle acceleration and a hardening of the radio-UV spectrum towards the UV, caused by a UV-excess emission component of unknown origin. Secondly, the X-ray emission mechanism for this jet remains unclear even with the well-resolved Chandra imaging. The proposed data will tell whether these two issues are related. If they are, as we predict, then we can study the X-ray emitters at the HST's full resolution using the proposed observations.

ACS/WFC 10174

Dark-matter halos and evolution of high-z early-type galaxies

Gravitational lensing and stellar dynamics provide two complementary methods to determine the mass distribution and evolution of luminous and dark-matter in early-type {E/S0} galaxies. The combined study of stellar dynamics and gravitational lensing allows one to break degeneracies inherent to each method separately, providing a clean probe of the internal structure of massive galaxies. Since most lens galaxies are at redshifts z=0.1-1.0, they also provide the required look-back time to study their structural and stellar-population evolution. We recently analyzed 5 E/S0 lens galaxies between z=0.5 and 1.0, combining exquisite Hubble Space Telescope imaging data with kinematic data from ground-based Keck spectroscopy, placing the first precise constraints on the dark-matter mass fraction and its inner slope beyond the local Universe. To expand the sample to ~30 systems -- required to study potential trends and evolution in the E/S0 mass profiles -- we propose to target the 49 E/S0 lens-galaxy candidates discovered by Bolton et al. {2004} from the Sloan Digital Sky Survey {SDSS}. With the average lens rate being 40% and some systems having a lensing probability close to unity, we expect to discover ~20 strong gravitational lenses from the sample. This will triple the current sample of 9 E/S0 systems, with data in hand. With the sample of 30 systems, we will be able to determine the average slope of the dark-matter and total mass profile of E/S0 galaxies to 10% and 4% accuracy, respectively. If present, we can simultaneously detect 10% evolution in the total mass slope with 95% confidence. This will provide unprecedented constraints on E/S0 galaxies beyond the local Universe and allow a stringent test of their formation scenarios and the standard cosmological model.

NIC/NIC3 10226

The NICMOS Grism Parallel Survey

We propose to continue managing the NICMOS pure parallel program. Based on our experience, we are well prepared to make optimal use of the parallel opportunities. The improved sensitivity and efficiency of our observations will substantially increase the number of line-emitting galaxies detected. As our previous work has demonstrated, the most frequently detected line is Halpha at 0.7<z<1.9, which provides an excellent measure of current star formation rate. We will also detect star-forming and active galaxies in other redshift ranges using other emission lines. The grism observations will produce by far the best available Halpha luminosity functions over the crucial--but poorly observed--redshift range where galaxies appear to have assembled most of their stellar mass. This key process of galaxy evolution needs to be studied with IR data; we found that observations at shorter wavelengths appear to have missed a large fraction of the star-formation in galaxies, due to dust reddening. We will also obtain deep F110W and F160W images, to examine the space densities and morphologies of faint red galaxies. In addition to carrying out the public parallels, we will make the fully reduced and calibrated images and spectra available on-line, with some ground-based data for the deepest parallel fields included.

NIC3 9780

NIC3 Imaging of z~6 Candidates in a Deep ACS Parallel Field: Finding the reionizing population and their LF

A fundamental cosmological question is when and how the universe was reionized. It is now generally believed that the reionization ended by z=6. There is evidence that QSO/AGN cannot provide enough photons to keep the universe ionized at that epoch. In Yan et al. {2003}, we presented a first statistically significant sample of 6.0<z<6.5 galaxy candidates, 30 objects in total found in a deep ACS/WFC parallel field by using the "drop-out" technique, and argued that the contamination due to possible contaminators was minimal. We concluded that young, star-forming galaxies did exist in large number as expected from our earlier work {Yan et al. 2002}, and that they could have contributed most of the reionizing photons. The candidates in our sample have a median magnitude of AB=27.4 mag, beyond the spectroscopic capability of any existing facilities. Any effort of acquiring a large sample of galaxies around z=6 will have the vast majority of candidates at such a faint brightness level. Thus near-IR imaging is the only practical way to further confirm the nature and the redshifts of these candidates until the launch of the JWST. Here we propose to use the NIC3 of the NICMOS to image 43% of our sample in the F110W and F160W bands to unambiguously confirm their nature. We will image 13-14 of our candidates with two NIC3 fields, and request 16 orbits of observation in total. With this data set, we will be able to determine the surface density of galaxies at the crucial epoch around z=6, and derive photometric redshift for our candidates. Our result will set stringent limits to the faint-end slope of the luminosity function {LF} and the star formation rate at z=6, and thus provide essential constraints to a series of questions regarding the reionization of the universe.

STIS/CCD/MA1/MA2 10080

Wavelength Stability of Narrow Band and Linear Ramp Filters

Verify the mapping of wavelength as a function of CCD position on LRFs; check for changes in central wavelengths of narrow band filters.

WFPC2 10071

WFPC2 CYCLE 12 Supplemental Darks Part 3/3

This dark calibration program obtains 3 dark frames every day to provide data for monitoring and characterizing the evolution of hot pixels.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)

HSTAR 9504: OTA SE review of PTAS processing log for SMS SA208O revealed LOL experienced in the GS Acquisition (3,2,2) @ 213/16:09:41Z. Both FGSs were in FLDV @ 213/16:13:01Z, but at 213/16:14:35Z, both returned to SSM control and successfully achieved FLDV by 213/16:15:33Z. Under investigation.

HSTAR 9505: GS Acquisition (2,1,1) @ 218/04:00:15Z resulted in FL backup (2,0,2) due to SRLE on FGS 1. FHST FM Updates @ 218/03:40Z and 03:43Z were both successful with attitude error. FHST Map scheduled @ 218/04:35Z showed attitude error of -2.596, -7.167, and -1.600 arcsec.

COMPLETED OPS REQs:

  • 17240-0 - Genslew for proposal 9703 - slot 10 @ 217/2115z
  • 17241-0 - Genslew for proposal 9703 - slot 11 @ 217/2117z
  • 17242-0 - Genslew for proposal 9703 - slot 12 @ 217/2118z
  • 17243-0 - Genslew for proposal 9703 - slot 13 @ 217/2120z

OPS NOTES EXECUTED: 1254-0 - Lower STIS Zone Temperature Limits, OTCZ3BT and OTCZ2BT @ 217/1929z

                        SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq             7                         7
FGS REacq             10                       10
FHST Update           9                          9
LOSS of LOCK

SIGNIFICANT EVENTS:

Executed GENSLEW for Proposal 9703 "Coronagraphic Search for Planets around Nearby Stars", Slot 10 @ 217/21:15Z, Slot 11 @ 217/21:17Z, Slot 12 @ 217/21:18Z, and Slot 13 @ 217/21:20Z (OR 17240 - 17243).

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